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Framework for an AI-Ready ARPES Community Database

Zhi-Xun Shen, Jin Gene Wong, Karen Lei, Leon Garcia, Felix Baumberger, Sergey Borisenko, Aaron Bostwick, Ting Cao, Tanny Chavez, Yulin Chen, Monika Choudhary, Andrea Damascelli, Dan Dessau, Thomas P. Devereaux, Sandy A. Ekahana, Alexei Fedorov, Atsushi Fujimori, Yucheng Guo, M. Zahid Hasan, Makoto Hashimoto, Yu He, Philip Hofmann, Zahid Hussain, Harold Y. Hwang, Zhurun Ji, Chunjing Jia, Timur K. Kim, Phil D. C. King, Takeshi Kondo, Alessandra Lanzara, Chun Lin, Donghui Lu, Matteo Michiardi, Sung-Kwan Mo, Brian Moritz, Laurenz Rettig, Eli Rotenberg, Takafumi Sato, Kyle M. Shen, Jonathan A. Sobota, Inna Vishik, Shuolong Yang, Ming Yi, Timothy Zaklama

Year: 2026Venue: arXiv preprintArea: cond-mat.mtrl-sciType: PreprintEmbeddings: 136

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Abstract

Abstract:Condensed matter stands to gain profoundly from widespread adoption of artificial intelligence (AI). However, its current means of data organization impedes this endeavor. As a premier measure of electronic structure underlying material properties, Angle-Resolved Photoemission Spectroscopy (ARPES) has accumulated over four decades of spectra, yet the community's publication-centered workflow preserves only a highly selected fraction of its experimental record. A shared data ecosystem could transform these fragmented measurements and their contexts into a persistent, collective scientific memory, creating immediate value for reproducibility and reuse while laying the foundation for AI-enabled discovery. In this Perspective, we report outcomes of a recent community workshop and propose a practical path toward such an ecosystem. Its benefits unfold along three timescales. In the near term, standardized, searchable, and citable datasets strengthen analysis pipelines independently of AI. In the intermediate future, community-validated tools operating across laboratories could enable broader reuse and increasingly closed-loop automated experiments. In the long term, a diverse corpus of measured electronic spectra could support foundation models for quantum matter. Looking forward, a diverse corpus of measured electronic spectra could support foundation models for quantum matter and new discoveries. We discuss lessons from existing scientific databases, the current state of AI in ARPES, as well as areas of community convergence on data organization, access, credit, governance, and a staged pilot program.

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Framework for an AI-Ready ARPES Community Database Zhi-Xun Shen, 1, 2, 3, 4, 5,∗ Jin Gene Wong, 1, 3, 4, 5 Karen Lei, 1, 3, 4, 5 León Garcia, 1, 5 Felix Baumberger, 6, 7 Sergey Borisenko, 8 Aaron Bostwick, 9 Ting Cao, 10 Tanny Chavez, 9 Yulin Chen, 11 Monika Choudhary, 9 Andrea Damascelli, 12, 13 Dan Dessau, 14 Thomas P. Devereaux, 3, 15, 16 Sandy A. Ekahana, 17, 9 Alexei Fedorov, 9 Atsushi Fujimori, 18, 19, 20 Yucheng Guo, 21 M. Zahid Hasan, 22, 23 Makoto Hashimoto, 24 Yu He, 25 Philip Hofmann, 26 Zahid Hussain, 27 Harold Y. Hwang, 3, 2 Zhurun Ji, 28 Chunjing Jia, 29 Timur K. Kim, 30 Phil D. C. King, 31 Takeshi Kondo, 32 Alessandra Lanzara, 27, 33 Chun Lin, 24 Donghui Lu, 24 Matteo Michiardi, 13 Sung-Kwan Mo, 9 Brian Moritz, 3 Laurenz Rettig, 34 Eli Rotenberg, 9 Takafumi Sato, 35, 36, 37, 38, 39 Kyle M. Shen, 40, 41 Jonathan A. Sobota, 3 Inna Vishik, 42, 27 Shuolong Yang, 43 Ming Yi, 21 and Timothy Zaklama 28 1 Physics Department, Stanford University, Stanford, California 94305, USA 2 Applied Physics Department, Stanford University, Stanford, California 94305, USA 3 Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA 4 Geballe Laboratory for Advanced Materials (GLAM), Stanford University, Stanford, CA 94305, USA 5 Stanford Laboratory for Intelligent Matter, Stanford University, Stanford, CA 94305, USA 6 Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland 7 Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland 8 Leibniz Institute for Solid State and Materials Research, IFW Dresden, 01069 Dresden, Germany 9 Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA 10 Department of Materials Science and Engineering, University of Washington, Seattle, Washington 98195, USA 11 Department of Physics, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, UK 12 Department of Physics & Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada 13 Quantum Matter Institute, University of British Columbia, Vancouver, British Columbia, V6T 1Z4, Canada 14 Department of Physics, University of Colorado Boulder, Boulder, Colorado 80309, USA 15 Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, USA 16 Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA 17 Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA 18 Department of Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan 19 National Synchrotron Radiation Research Center, Hsinchu 300092, Taiwan 20 Center for Quantum Technology, and Department of Physics, National Tsing Hua University, Hsinchu 300044, Taiwan 21 Department of Physics and Astronomy, Rice University, Houston, Texas 77251, USA 22 Laboratory for Topological Quantum Matter and Advanced Spectroscopy, Department of Physics, Princeton University, Princeton, New Jersey 08544, USA 23 Princeton Materials Institute, Princeton University, Princeton, New Jersey 08544, USA 24 Stanford Synchrotron Radiation Lightsource, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA 25 Department of Applied Physics, Yale University, New Haven, Connecticut 06511, USA 26 Department of Physics and Astronomy, Aarhus University, 8000 Aarhus C, Denmark 27 Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA 28 Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA 29 Department of Physics, University of Florida, Gainesville, Florida 32611, USA 30 Diamond Light Source Ltd, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK 31 School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9S, UK 32 Institute for Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8581, Japan 33 Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA 34 Fritz Haber Institute of the Max Planck Society, Faradayweg 4-6, 14195 Berlin, Germany 35 Department of Physics, Graduate School of Science, Tohoku University, Sendai 980-8578, Japan arXiv:2610.15236v1 [cond-mat.mtrl-sci] 11 Oct 2026 2 36 International Center for Synchrotron Radiation Innovation Smart (SRIS), Tohoku University, Sendai 980-8577, Japan 37 Mathematical Science Center for Co-creative Society (MathCCS), Tohoku University, Sendai 980-8578, Japan 38 Advanced Institute for Materials Research (WPI-AIMR), Tohoku University, Sendai 980-8577, Japan 39 Center for Science and Innovation in Spintronics (CSIS), Tohoku University, Sendai 980-8577, Japan 40 Laboratory of Atomic and Solid State Physics, Department of Physics, Cornell University, Ithaca, New York 14853, USA 41 Kavli Institute at Cornell for Nanoscale Science, Ithaca, New York 14853, USA 42 Department of Physics and Astronomy, University of California Davis, Davis, California 95616, USA 43 Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, USA Condensed matter stands to gain profoundly from widespread adoption of artificial intelligence (AI). However, its current means of data organization impedes this endeavor. As a premier measure of electronic structure underlying material properties, Angle-Resolved Photoemission Spectroscopy (ARPES) has accumulated over four decades of spectra, yet the community’s publication-centered workflow preserves only a highly selected fraction of its experimental record. A shared data ecosys- tem could transform these fragmented measurements and their contexts into a persistent, collective scientific memory, creating immediate value for reproducibility and reuse while laying the foundation for AI-enabled discovery. In this Perspective, we report outcomes of a recent community workshop and propose a practical path toward such an ecosystem. Its benefits unfold along three timescales. In the near term, standardized, searchable, and citable datasets strengthen analysis pipelines inde- pendently of AI. In the intermediate future, community-validated tools operating across laboratories could enable broader reuse and increasingly closed-loop automated experiments. In the long term, a diverse corpus of measured electronic spectra could support foundation models for quantum matter. Looking forward, a diverse corpus of measured electronic spectra could support foundation models for quantum matter and new discoveries. We discuss lessons from existing scientific databases, the current state of AI in ARPES, as well as areas of community convergence on data organization, access, credit, governance, and a staged pilot program. Artificial intelligence (AI) is transforming how scientific inquiry is conducted across an expanding range of disciplines. Data, and the context needed to interpret them, have played a decisive role in this transformation. Theoretical research benefits from extensive databases of calculations; structural sci- ences have mature data repositories amassed over decades, such as the Protein Data Bank for biology. In contrast, experimental condensed matter physics largely lacks standardized data repositories, instead responding to recent data availability requirements in an ad hoc manner. Organizing community-wide data no longer just serves to ensure reproducibility, it also becomes the key step to enable AI-native sci- ence in the future. The community needs to organize their data now — not with AI initially in mind, but simply to make today’s science more reproducible and reusable. Many of the most profound questions in con- densed matter can only be answered by reasoning over broad classes of materials, an undertaking for which today’s single-system approach to data col- lection, analysis, and publication proves inadequate. This calls for large community repositories of ex- perimental data to be assembled, in a manner that both fortifies the current scientific workflow and ∗ Corresponding author: zxshen@stanford.edu sets the ground for deeper AI adoption. Angle- Resolved Photoemission Spectroscopy (ARPES), with its information-rich measurements and close connection to the microscopic “ground truth” of ef- fective lattice models, provides a timely test case for changing the modus operandi. This offers the oppor- tunity to transform decades of fragmented experi- mental experience into a persistent, computationally accessible collective memory of electronic structure. A recent workshop at Stanford University brought together members of the ARPES community to ex- plore this opportunity [1]. This Perspective draws on discussions at that workshop to present a viable road map for the community, and as a request for the rest of the community to join our effort. We examine why ARPES data are scientifically distinc- tive, what is lost under current data practices, what new forms of science the ecosystem could enable, and what principles should guide its construction. We note that not all matters were resolved at the con- ference — consultation with the ARPES community, guided by a steering committee (Supplementary Sec- tion S8) elected by conference participants, and the creation of pilot databases to catch and rectify issues are all necessary prerequisites before the ecosystem may be scaled up. This paper has three primary intents: (1) to convince the ARPES community of the value of this endeavor not just by laying out a vision in this paper, (2) to invite all interested par- 3 ties to our follow-up workshops on future steps, and (3) highlight concrete demonstrations of its poten- tial through pilot projects deployed in the immediate future. I. WHY ELECTRONIC STRUCTURE MATTERS, AND THE ARPES OPPORTUNITY Electronic structure is the microscopic physical foundation that underpins many crucial material properties. By describing the behavior of quasi- particles (which emerge from electrons coupling to spin, lattice, and orbital degrees of freedom) it deter- mines important macroscopic properties such as the development of collective order, bulk transport prop- erties (including conductivity, magnetism, and opti- cal response), as well as catalytic properties. Elec- tronic and crystal structures are strongly interde- pendent and may be jointly viewed as the “genome” of a material; while not a description of a system in its entirety, they are a compact microscopic basis from which physical properties could be understood. ARPES provides direct access to electronic struc- ture by measuring the energy and momenta of pho- toemitted electrons (Fig. 1) [2, 3]. These electrons are collected by analyzers, which generate spectra from the measurements, giving insight into micro- scopic ingredients that thus determine macroscopic properties. For conventional equilibrium measure- ments, ARPES primarily probes the occupied one- electron spectral function, modulated by photoemis- sion matrix elements and experimental resolution. While pump-probe approaches and inverse photoe- mission extend access above the Fermi level, con- ventional ARPES comprises the vast majority of ex- periments performed, and is thus the focus of this Perspective. Because ARPES resolves band dispersions and many-body effects, it has played a central role in the study of major quantum materials such as cuprate and iron-based superconductors, topological mate- rials, and two-dimensional systems [2–5]. Com- ing a long way since its emergence in the 1970s, it has matured into a broadly quantitative, high- resolution probe of many-body electronic structure [6, 7]. As shown in Fig. 2, bursts of activity fol- lowed high-resolution studies of the cuprates in the early 1990s, exemplified by the confirmation of d- wave pairing [8], and the spread of ARPES from the late 2000s to graphene [9, 10], topological [11–13], two-dimensional [14–16], and other quantum mate- rials [17–19], powered by development from hemi- spherical analyzers [20, 21] to new two-dimensional imaging [22], and multidimensional data collection schemes [23]. New modalities including momentum microscopy [23–25], time [26], spin [11, 27], and spa- tial [28, 29] resolution, and magnetic fields [30, 31] continue to expand both the scientific scope of the technique and the volume and dimensionality of the data it produces. I. FROM COMPLICATED AND FRAGMENTED DATA — TO COLLECTIVE SCIENTIFIC MEMORY A. ARPES data are extremely rich, but they come with inherent complexity Although ARPES is an extremely powerful ex- perimental technique, data interpretation is com- plicated. It measures electronic structure, but its recorded intensity is not the theoretical spectral function (Table I) — it depends strongly on ex- perimental context, including experimental geome- try, instrumental resolution and detector response, coordinate transformations, data-processing choices, and (perhaps most crucially) exceptional sensitiv- ity to sample surface conditions at the time of mea- surement. Like scattering techniques such as X-ray diffraction, ARPES samples only slices of a high- dimensional momentum space, whose exact loca- tions in that space are revealed in post-processing. For these reasons, measurements that should cap- ture identical theoretical spectra can look substan- tially different across beamlines, samples, locations on a sample, or times after cleavage. The central data challenge is therefore to preserve and standard- ize the experimental context required for successful interpretation. B. The current ARPES workflow is suboptimal Because experimental context is currently dis- carded in disseminated ARPES data, there is a sig- nificant opportunity gap between the potential of ARPES and its data practice in reality (Fig. 3). Today’s workflow terminates largely in publication, while analysis code and much of the raw measure- ment data remain localized to specific laboratories, rather than in persistent scientific infrastructure. An experienced researcher knows, for example, what a bad cleave looks like, which weak feature is likely a matrix element effect, which anomaly has appeared before, which measurement condition unexpectedly worked, and which apparent discovery has already failed to reproduce across many other samples. When people leave the field, a substantial fraction of their informal, unstructured knowledge disappears. 4 FIG. 1. Electronic structure is the genome of quantum materials, and ARPES reads it. Top: for a given crystal structure in real space (left), ARPES measures the momentum-resolved electronic structure — the photoemission intensity I(k x , k y , E) in momentum–energy space (right). Bottom: each class of spectral observable (left column) exposes a physical ingredient of the material, its “gene” (center), which helps determines a macroscopic consequence, the “phenotype” (right): band dispersions locate the Fermi surfaces and band gaps that separate metals, insulators, and semiconductors; gap openings signal the electron pairing behind superconductivity; bands inverts encode the wave function topology in spin-orbit coupled systems behind quantized transport; and spectral anomalies reveal the electron correlations behind emergent phases. ARPES intensity volume adapted from data in [32] with permission. 5 TABLE I. Complications in ARPES and their ramifications. ARPES context/development What should be preserved or accommodated Photoemission matrix elementsPhoton energy, polarization, experimental geometry, other parameters controlling measured intensity Instrument responseEnergy/angular resolution, detector characteristics, calibration, and analyzer settings High-dimensional samplingRaw measured coordinates and information describing how the underlying multidimensional space was sampled Sample environmentFor example, applied fields, strain, currents, optical excitation, correlating ARPES to transport measurements; should preserve information on instruments used for setting and measuring these conditions, and sample responses Coordinate conversionEmission angles, manipulator conventions, photon geometry, analyzer configuration, and transformations into momentum space Surface sensitivitySample identity, cleavage history, measurement location, temperature/time history, aging, and spectral-quality evolution, including XPS reference spectra where available Data processingProcessing steps and parameters, while retaining access to less-processed or raw representations Increasing dimensionalityEvolution from 1D spectra→ 2D energy–momentum maps→ full momentum/TOF mapping→ spatial (micro- and nano-ARPES), spin, and time-resolved datasets Cross-instrument variabilitySufficient provenance to compare measurements across beamlines, laboratories, instruments, and experimental sessions Metadata standardsA common community-defined description of signal, coordinates, experimental conditions, and provenance Open-data practiceHarmonization of currently piecemeal publication-linked repositories into a searchable, reusable community resource As in Fig. 3(a), the conventional ARPES workflow is largely linear—measurement, record, analysis, pub- lication—with information lost at each step. Pub- lished figures further select strongly for successful and interpretable measurements, while unsuccessful, ambiguous, and seemingly uninteresting spectra are rarely preserved, despite encoding valuable informa- tion about experimental conditions, failure modes, and the scientific target itself. These losses will compound and become increas- ingly consequential as measurement throughput in- creases. The field faces a growing mismatch be- tween what it can measure and measurements it is already capable of making. We intend to stem this loss of information and knowledge by cre- ating a community-wide ARPES data ecosystem [33]—an environment for creating, managing, shar- ing, and sustaining experimental data and their con- text—and encourage analogous efforts elsewhere in condensed matter physics. As illustrated schemat- ically in Fig. 3(b), the essential change is to make publication a waypoint rather than the endpoint of an experiment. A sufficiently rich database, ulti- mately including unsuccessful and ambiguous mea- surements alongside published results, would consol- idate previously siloed and perishable experimental data into a shared, persistent framework. With both dataset volumes and publication activity still grow- ing (Fig. 2), now is an opportune moment to estab- lish a practitioner-driven standard before incompat- ible local conventions become entrenched. C. Immediate opportunities of the ecosystem — before foundation models Immediate benefits of the ecosystem flow straight to the community, independently of AI involvement. These include data preservation, findability, and credit. Published datasets themselves, not just the papers, become durable, searchable, citable research objects. Because a substantial fraction of histor- ically important data resides on aging local stor- age, and in formats that depend on obsolete soft- ware whose data processing pipelines linking them to published results are not reproducible without ex- tensive documentation, preservation would be vastly improved by standardization. These immediate ben- efits form a durable bedrock from which broader AI applications may be built. Beyond preservation, the ecosystem could scale up existing workflows [34]. It would allow the commu- 6 1991200020102020 Year 0 100 200 300 400 Publications per year (a) Quantum-materials publications related to ARPES 1991200020102020 Year 0 10k 20k 30k Citations per year (b) Citations of the publications in (a) 1991200020102020 Year 0 25 50 75 100 125 Distinct materials per year (c) Distinct materials studied per year, ARPES 1991200020102020 Year 0 100 200 300 400 500 600 Publications per year (d) Quantum-materials publications by technique X-ray scattering X-ray spectroscopy Neutron scattering STM / STS ARPES FIG. 2. Growth of ARPES activity, impact, and material coverage in quantum materials, from Web of Science (current as of September 2026 with totals cover 1991-2025). (a) Publications per year matching an All Databases search for “angle-resolved photoemission” and its spelling and acronym variants (ARPES, angle resolved photo emission, etc.), restricted by a keyword filter to quantum-materials topics (correlated electrons and superconductivity, topology, quantum magnetism, and moiré and kagome lattices) and excluding preprints, Research Commons, datasets, grants, and patents; 7,188 records in total. (b) Citations received in each calendar year by the publications in (a), 341,862 in total. Citations are binned by the year in which they accrue, so recent years are not suppressed by citation lag. (c) Distinct materials named in the titles of the publications in (a). Materials are identified by parent compound and distinct stoichiometries count separately (Bi 2 Sr 2 CuO 6 vs. Bi 2 Sr 2 CaCu 2 O 8 ), doping and strain collapse onto the parent (La 2−x Sr x CuO 4 counts as La 2 CuO 4 at every x), solid solutions resolve onto their independently studied endmembers (FeSe 1−x Te x counts as FeSe and FeTe), and a film on a substrate is distinct from the bulk (FeSe/SrTiO 3 vs. FeSe). Since only titles are parsed, these counts are approximate; 726 distinct materials appear in total. (d) Publications per year for five experimental probes of quantum materials under equivalent searches, each for the technique’s name as an exact phrase without acronyms and restricted by the same filter, so the ARPES curve holds 85% of the publications in (a). X-ray spectroscopy covers X-ray absorption, emission and dichroism; resonant inelastic X-ray scattering is counted under X-ray scattering, and X-ray photoelectron spectroscopy is not included. The X-ray and neutron search strings match families of related techniques whereas the ARPES string matches a single technique, so cross technique ratios are indicative rather than exact. All panels begin in 1991, the first year the Web of Science Core Collection indexes abstracts and author keywords; a title-only control confirms that the large apparent 1990-91 jump in its topic-search counts is an indexing artifact, and earlier counts, which mostly reflect title wording, are omitted. nity to learn from what papers currently leave out: ineffective, ambiguous, and seemingly “uninterest- ing” measurements provide negative examples and experimental knowledge that are rarely preserved in the published record, yet can be highly informative when viewed collectively. The ecosystem could func- tion as a scientific time machine, allowing phenom- ena conceived or understood only in the future to be searched retrospectively across measurements taken years or even decades earlier (known elsewhere as precovery) so that old experiments could yield gen- uinely new discoveries. A sufficiently broad corpus could act as an “anomaly telescope”, directing at- tention to spectra that resist classification and may contain either hidden experimental problems or un- expected physics. The most profound questions in ARPES involve recognizing patterns across material families, which depends on decades of accumulated personal experi- ence. Beyond predefined material categories such as 7 FIG. 3. The endpoint of an ARPES experiment, today and with a shared archive. Left: the prevailing linear workflow — measure, record locally, analyze with private code, publish a figure. Downward arrows mark where information leaks at each stage. After four leaks, each dataset ends where its group ends, and reuse is blocked. Right: the same five steps closed into a loop around a shared commons — standardized ingest, validated analysis tools, DOI-based sharing with notification tiers, and reuse by both people and models, so that any measurement can be checked for consistency, guide the choice of the next experiment, and train models. The change is organizational rather than instrumental: a common, searchable index with provenance, not new hardware. cuprates, kagome metals, or Weyl semimetals, im- portant electronic behaviors and organizing princi- ples may be distributed across chemically and struc- turally unrelated systems. An ecosystem could make that breadth of experience more accessible, allowing younger researchers to compare far more measure- ments and material classes than datasets available at any individual laboratory. I. FROM TODAY’S AI TOOLS TO MODERN AI-ENABLED SCIENCE A. What other data ecosystems teach us Structural techniques have had the most success so far in constructing community-wide databases, because of their compact representations and ob- vious downstream uses. Major examples include the Inorganic Crystal Structure Database (ICSD) [35] and PubChem [36]. Within condensed matter, non-structural databases include NIMS databases such as the Materials Data Repository [37] for Hard X-ray Photoelectron Spectroscopy (HAXPES) and X-ray Absorption Fine Structure (XAFS), the X- ray Absorption Spectroscopy (XAS) Data Library [38], and nmrXiv for Nuclear Magnetic Resonance (NMR) [39]. However, the textbook precedent for building a community data ecosystem lies outside physics — the Protein Data Bank (PDB), which col- lects and organizes protein sequences and structures, having grown over several decades into a database with over a quarter-million experimentally deter- mined structures [40, 41]. Recent breakthrough AI models such as AlphaFold were substantially trained on experimentally determined PDB structures, sup- plemented by self-distillation on predicted structures [42]. We emphasize that the PDB was not created for AlphaFold, but because structural biology needed a durable shared record. Transformative yet unantici- pated downstream uses only emerged decades later. ARPES differs from structural techniques and their databases (such as the PDB) in one fun- damental respect: while structural results are re- ducible to a compact representation easily agreed upon by the community with well-developed vali- dation conventions—encoding atomic or molecular structure—ARPES data lack an equally universal representation. As detailed in Table I, spectral intensity is entangled with experimental context, and detailed analysis depends on bespoke analysis pipelines or models. An ARPES ecosystem must remedy this using standardized spectral data for- mats and benchmarks, with careful attention paid to tiering by data quality [43], while retaining origi- 8 nal data in the database, as opposed to earlier struc- tural databases in which only processed results were made available. B. Status of AI in ARPES today Despite increasing AI adoption in ARPES, the community currently relies on models operating within a pre-foundation model paradigm: they are trained on curated datasets for specific tasks with limited generalization to unseen, out-of-distribution data. Current applications broadly fall into three categories. (1) Analysis: AI-based denoising recov- ers useful structure from low-count spectra, includ- ing uncertainty estimates for quantitative analysis [44, 45]; simulation tools such as chinook and syn- thetic ARPES pipelines support model development and training such as aurelia [46, 47]; and automated methods are being developed for feature extraction, phase classification, and dispersion tracking [48–51]. (2) Representation and generalization: representa- tion learning and self-supervised embeddings enable few-shot classification and spatial-domain mapping with limited labels, while also exposing the need for a much larger and more diverse community dataset [52, 53]. (3) Experiment control: autonomous micro- ARPES using Gaussian-process-guided search has already demonstrated AI-directed measurement in real and momentum space [54], while broader efforts toward embodied experimental agents in quantum materials point to the next stage of ARPES au- tomation [55–59], towards closed-loop experiments where data collected in real time drives experiments forward without human involvement. We empha- size that these models would nevertheless already benefit from the construction of the ecosystem, by expanding the scale and diversity of their training data alone, even before foundation models are con- structed. C. Towards future foundation models Robustness, the ability to generalize dependably out of distribution (that is, to cases not represented in the training set), depends critically on broader and more diverse training data, not only on model architecture. Models trained on narrow experimen- tal or synthetic datasets struggle when tackling unfa- miliar band structures, detector conditions, or sam- ple states. As previous work such as aurelia [47] have demonstrated, synthetic data can provide scale, but a large, diverse, and well-curated body of ex- perimental data is essential for realism, validation, and reliable generalization. A foundation model ap- proach offers a path beyond this limitation [60]. The model is first pre-trained on large, diverse datasets to learn general representations, and then adapted to specific tasks using smaller, high-quality experi- mental datasets. Because pre-training requires scale [61, 62], it may combine large synthetic corpora with increasingly broad collections of experimental spec- tra, while measured data remain essential for cap- turing the complexities omitted by simulation. The more consequential possibility is not more ro- bust performance on existing tasks, but qualitatively new capabilities that emerge from learning across a sufficiently broad corpus. Such capabilities could include recognizing phenomena unknown when the data were taken, identifying recurring patterns that define previously unnamed classes of quantum mat- ter, and continuously ranking measurements by sci- entific anomaly. Further on, multimodal models could further connect ARPES with crystal structure from X-ray and neutron diffraction, scanning tun- neling microscopy/spectroscopy (STM/STS), trans- port, inelastic scattering, optical spectroscopy, and theory, allowing relationships to emerge across mea- surements that are currently analyzed separately. In the longer term, linking such representations to crys- tal structures, synthesis data, and materials mod- els could also enable inverse questions: not only what electronic structure a material possesses, but what materials might realize a desired electronic structure. Building a centralized, AI-ready global ARPES database aims to convert decades of frag- mented experimental electronic structure data into a workable basis for foundation models for quantum materials and novel phenomena discovery. A sum- mary of future possibilities in AI-enabled scientific discovery is given in Table I. Realizing this vision will require substantial com- munity involvement to tackle questions en route to foundation models. The gap between simulated and experimental spectra—including unknown self- energies, matrix elements, backgrounds, and instru- mental artifacts—must be addressed during model development. There is an inherent trade-off: train- ing on synthetic data promises scale, but propa- gates mistaken assumptions from the simulator to the data, while experimental data provide real- ism but remain noisy and limited. Unsupervised learning techniques, such as data augmentation and contrastive learning, as well as multimodal fusion to incorporate other experimental techniques, are promising avenues of research. The optimal archi- tecture is also not yet known and should be designed around scientific data rather than inherited uncriti- cally from language or computer vision. The central opportunity is therefore not a particular AI architec- ture, but a sufficiently rich and well-organized data 9 foundation from which increasingly general scientific models can emerge. IV. DESIGNING AN ARPES DATA ECOSYSTEM FOR REUSE AND DISCOVERY Because important matters of debate should only be resolved in consultation with the broader ARPES community, the workshop also established an ini- tial steering committee through an anonymous vote of participants. The committee will coordi- nate follow-up work, engage the broader community, and develop solutions to unresolved technical, pol- icy, and governance questions. We summarize our discussion on metadata in Section IV A and carefully point out areas of convergence and disagreement in Section IV B. We anticipate that resolving technical and other differences would involve both the setting up of pilot databases (Section IV C) in consultation with the community guided by the steering commit- tee. A. Organizing data and metadata A promising technical reference for organizing data is the NeXus/HDF5 framework [63], and its application NXmpes for ARPES which builds on the FAIR data principles [64], in broad alignment with other segments of the condensed matter com- munity [65]. This provides an existing community language for data and metadata which may be repur- posed for the repository, rather than requiring the community to invent a new container from scratch. With the possibility of AI in mind, the community should consider a careful redesign of data infras- tructure, while referencing existing efforts such as NEXUS/NXmpes, other existing technical founda- tions [50], or other data management principles such as ALCOA and its successors [66]. In addition, we propose dividing metadata into two layers. The first, a compact mandatory core, should be sufficient to interpret experimental geom- etry and reconstruct momentum coordinates (a de- rived quantity based on analyzer and beamline/light source setting). This would include essential infor- mation such as photon energy and polarization, mea- sured angular coordinates and kinetic energy, and may include other information such as analyzer and manipulator conventions, sample temperature, rel- evant resolutions, sample orientation, and schema version; specifics should be decided by the steering committee. The second layer comprises extensible context in the form of free text annotations, includ- ing (but not limited to) sample growth and han- dling, cleavage or preparation history, device state, pressure or field, detector calibrations, processing history, and experimental intent. Lastly, the com- munity should adopt far more systematic means of metadata collection: all metadata for sample cre- ation should be captured, such as end-to-end note- books that spans sample preparers to ARPES mea- surements, and automation should be scaled up so that all metadata generated during measurement is captured by default in a standardized format. Atten- tion should be paid to the capacity of data hosting platforms, in anticipation of a sharp growth in the volume of data collected. B. Areas of convergence Table I summarizes the principal issues raised at the workshop, possible remedies, and the degree of consensus reached. A primary topic of discussion was how data and metadata should be organized. An option is to start with published data: these provide the lowest-friction pilot because their scientific re- sults are already public and priority concerns are reduced. The matter of handling unpublished data warrants careful consideration. Additionally, data should be converted on ingest, so that no labora- tory or beamline is required to abandon its estab- lished acquisition formats before the community re- source becomes useful, and the onus of conversion should not fall on them. Whatever the source for- mat, the archive should preserve raw measured co- ordinates and provenance rather than baking irre- versible momentum-space conversions or processing choices into an only stored representation. Consis- tent with the goal of broad adoption, mandatory metadata core should be kept small while allowing extensions: the initial adopted standard should be practical enough to be adopted, rather than com- prehensive enough to be complete. Free-text anno- tations should be treated as data in their own right, because experimental judgment and decision context are not fully captured by any fixed schema. We also consider how the data should be hosted and used. Questions of credit and access are fore- most concerns of the ARPES community, and should be treated carefully. Datasets should carry persis- tent identifiers and explicit credit, so that dataset citation becomes normal scholarly practice rather than lapse into being a mere informal courtesy. Ac- cess tiers should be supported, since pure openness cannot be the only path to participation when fa- cility, incentive or institutional constraints differ. The community should first explore several pilot hosting sites before selecting permanent infrastruc- 10 TABLE I. Possibilities in AI-enabled scientific discovery in condensed matter. CapabilityDescription Short Timescale Automated Spectral Analysis Encode standard ARPES analysis protocols (MDC/EDC fitting, dispersion and gap extrac- tion, self-energy determination) into reproducible pipelines that automatically extract the parameters experimentalists normally obtain by hand: tight-binding parameters, Fermi ve- locities, gaps, and self-energies, with calibrated uncertainties. Systematic Theory Benchmarking Use these extracted parameters to benchmark DFT, DMFT, GW, and quantum Monte Carlo against experiment systematically, scoring every spectrum in the database against competing theories with the same parameters and criteria rather than one case at a time. Cross Material Comparison Uniform extraction across decades of data enables comparison of kink energies, gap structures, and band renormalizations across material families and control parameters (doping, strain, temperature, twist angle), distinguishing universal physics from material-specific features. Anomaly DetectionAct as an “anomaly telescope” that continually ranks global experimental spectra to flag statistically extraordinary features, unexpected degeneracies, or unexplained spectral-weight transfers. Such tracking would allow the unanticipated discovery of new laws, thus new physics not envisioned in existing theory. Collective Experimental Memory & Open Access Preserve tacit experimental wisdom (identifying bad cleaves, sample degradation, and in- strumental artifacts) into persistent computational infrastructure, democratizing access to high-tier synchrotron or laser data for researchers globally. Long-Term Vision Closed-Loop Beamline Automation Implement real-time and high speed/throughput active learning at synchrotrons and X-ray Free Electron Laser (XFEL) facilities to optimize measurement parameters dynamically, ex- tract insights from ineffective/unpublishable data, and reanalyze historical datasets using modern calibration algorithms. Multimodal IntegrationLink ARPES data with complementary experimental techniques—such as STM, transport, optics, X-ray/neutron scattering to form a comprehensive model of empirical electronic struc- ture model, which can be the basis for discovering unanticipated laws of physics not envisioned in theory; for example, any physical Big Data sets are expected to contain meta-laws such as multidimensional topological structures signaling novel higher-order emergent physics. Universal Spectral Foundation Models Pre-train AI on millions of spectra across diverse materials, photon energies, temperatures, and polarizations to capture generalized band structure representations while decoupling true quasiparticle dispersions from experimental noise and matrix-element and other technique- related artifacts. Generative Inverse Materials Design Invert the materials discovery pipeline by allowing scientists to specify a desired momentum- space feature (such as a topological flat band pinned at the Fermi level) while generative AI proposes the necessary chemical composition, space group, and substrate conditions. ture. These pilots would provide empirical esti- mates of storage requirements, conversion effort, and metadata completeness. By having several indepen- dent pilot sites, early participation would be en- hanced, and best practices may be identified for a future link up into an eventual integrated sys- tem. Lastly, benchmark tasks and evaluation crite- ria should be defined early, allowing different anal- ysis and AI approaches to be compared systemat- ically before broader claims about general-purpose foundation models are made. C. Scaling up the program Because many differences in technical implemen- tation and community buy-in may can only be re- solved by through small-scale working demonstra- tions, we propose a practical path in three phases, each with defined outputs and goals to hit before moving on to the next. First, pilot databases are currently being set up by willing participants (see Supplementary Section S9) to jump start the program and resolve teething prob- lems early. These pilots should begin with published datasets contributed by multiple laboratories and facilities, spanning different instruments and local conventions. They should preserve native data, es- 11 TABLE I. Principal issues and remedies identified in workshop discussion. IssueWhy it mattersPossible remedyWorkshop sta- tus Data Deposition Metadata burden A universal schema can become too complex and discourage par- ticipation, while sparse metadata can make reuse impossible. Keep a small mandatory core (geometry/conditions); add optional extensions; version the schema; convert on ingest rather than forcing every instrument to change acquisition immediately. Retain free-text annotations and have more metadata fields (with the option to leave unfilled) to enforce standardization early. Broad agreement Raw versus processed data Raw data preserve future flexibil- ity, but processed data may be easier to reuse and much smaller. Use layered records: raw/native files to the extent fea- sible under storage capacity, standardized structured data, and curated question-specific products. Keep provenance between layers. Broad agreement, but open in detail Data Analysis Data quality is task-dependent Examples: spectra useful for band mapping may be inadequate for gap extraction or Fermi-level de- termination; detector nonlineari- ties and surface aging can create subtle artifacts; additional char- acterization of specimen/cleave, XPS, LEED, cleave photo, STM if in-situ; quality threshold of data to be posted Preserve calibration data and context; avoid a sin- gle database-imposed quality score; attach task-specific quality flags and uncertainty; allow attributed user com- ments; build automated checks that assist rather than gate deposition. The taking of calibration data in the first place may also be mandated. Broad agreement Simulation-to- experiment distribution shift Synthetic data are useful but in- herit approximations in the gen- erating theory and instrument model. Flag simulated data explicitly; benchmark on mea- sured held-out datasets; report uncertainty and out-of- distribution performance; use real data as the anchor for model validation. Unresolved point Data misuse Context-free spectra can be over- interpreted, or analyzed with in- appropriate corrections. Pair data with documented tools, provenance, owner notification or usage statistics, and clear uncertainty or processing metadata and tools. Prefer education and reproducible analysis over approval gates. Broad agreement Data Management Credit & attribution Depositors may lose visibility when data are reused at scale; sample growers and facilities are easily under-credited. Persistent dataset identifiers; creator/contributor meta- data including sample source; required citation for iden- tifiable dataset reuse; track usage. Develop a separate credit mechanism for whole-corpus model training. Crucial unresolved point Access, ownership, & facility policy Rights can depend on institu- tions, grants, facilities, propri- etary agreements, and embargoes. Support public, restricted, and non-distributable or training-only tiers; record rights metadata; perform le- gal review by source type; do not assume the depositor personally owns all data. Embargo period as an option. Broad agreement: tiering supported Hosting & scale Actual storage volume and growth rate are not yet known; general repositories have per-record limits (Zenodo defaults to 50 GB, with larger quotas possible) [67]. Run a storage census before selecting infrastructure; pi- lot with representative datasets; design for migration and mirroring; separate metadata/index services from bulk-object storage. Question of distributed or central- ized funding or hosting is unresolved. Crucial unresolved point Participation incentives Repository effort may fail if depo- sition demands extra work while providing no local benefit. Make the standard useful behind laboratory firewall: fast retrieval, automatic conversion, previews, shared analysis tools, one-click transition from private staging to publication. A credit system may encourage good data upload by showing usage statistics, akin to GitHub. Broad agreement, but open in detail Governance & maintenance A database can outlive the grant or institution that created it. Community governance, technical staff, stable funding, international coordination, transparent change control, and periodic review of standards and access policy. Broad agreement 12 tablish reusable converters into a common format, define a minimal metadata set sufficient to recon- struct geometry and provenance, and assign persis- tent identifiers, while avoiding premature attempts to impose a single experimental convention. Next, in phase 2 the community should then use pilot databases to find and fix problems be- fore they become ingrained in the larger ecosystem, testing whether the framework is sustainable, fair, and useful. In practice, this means estimating stor- age needs and securing a long-term hosting plan, agreeing on policies for attribution and access, and measuring the burden on contributors. This phase would include an end-to-end demonstration of the complete pipeline, from automatic metadata capture during an ARPES experiment to automatic upload into the database. Usefulness should be judged by whether researchers outside the contributing groups can find and reuse the data, and through a small set of benchmark tasks—such as cross-instrument dis- persion extraction, uncertainty-aware denoising, or cross-material similarity search—with held-out ex- perimental test sets and conventional analysis as a baseline. Finally, in phase 3, the community would scale up once the framework is tried, tested, and trusted. Scaling would then proceed in three directions: extending automatic metadata capture from the demonstration site to other participating facili- ties; expanding from standard ARPES to specialty measurement modes; and adding private or pre- publication staging under the access policies agreed in phase 2, alongside a broader suite of community analysis and experiment support tools. As the cor- pus grows in diversity and quality, AI tools validated on the community benchmarks could feed back into data acquisition and adaptive measurement, and ul- timately provide the basis for training future foun- dation models for ARPES. V. A PRACTICAL PATH FORWARD — AND LESSONS BEYOND ARPES Many issues faced by the ARPES commu- nity—such as sample identity and condition, exper- imental conditions, and handling of metadata—are shared with the rest of condensed matter. Therefore, the implications of our proposal extend well beyond ARPES. Experimental condensed matter physics in- creasingly produces data that are richer than what can be conveyed in papers, while much of the knowl- edge required to interpret those data remains tacit and vulnerable to loss as researchers move on, in- struments are decommissioned, and laboratories are shuttered. The very communities which understand these measurements should organize and preserve them now, while they can still determine what con- text matters and how it should be recorded. AI cer- tainly promises new possibilities and lends urgency, but the case for building an ecosystem remains fun- damentally scientific. The data ecosystem would qualitatively transform the modus operandi by changing what constitutes the scientific record in condensed matter — and how science itself is carried out. Instead of dissem- inating knowledge through publications—whose re- sults are selective interpretations of particular exper- iments—preserving reusable measurements together with the context needed to understand them would retain ambiguities, failures, alternative interpreta- tions, and experimental conditions that would oth- erwise disappear because they were deemed unwor- thy of publication at time of collection. This would unlock new possibilities for data use. Measurements made with one scientific goal in mind may contain evidence relevant to problems conceived later, and patterns distributed across unrelated materials may reveal organizing principles that no individual ex- periment could expose. The ecosystem would turn the accumulated experience of a community into a durable collective memory, one that can be searched, revisited, recombined, and interrogated by questions that may not yet exist. We cannot know which fu- ture discoveries such an ecosystem will enable, for we can only connect the dots looking backwards. The most valuable questions the data may answer may very well be those we have not yet learned to ask. ACKNOWLEDGEMENTS This research used resources of the Stanford Insti- tute for Materials and Energy Sciences, supported by the DOE Office of Basic Energy Sciences, Di- vision of Materials Sciences and Engineering un- der contract no. DE-AC02-76SF00515, the Stanford Synchrotron Radiation Lightsource, supported by the DOE Office of Basic Energy Sciences under con- tract no. DE-AC02-76SF00515, and Advanced Light Source, Supported by DOE Office of Basic Energy Sciences under contract no. DE-AC02-05CH11231. The Stanford Laboratory for Intelligent Matter pro- vided funding for the workshop. 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Bungartz, C. Felser, M. Greiner, A. Groß, C. T. Koch, K. Kremer, W. E. Nagel, M. Scheidgen, C. Wöl, and C. Draxl, Nature 604, 635 (2022). [66] A. K. Rattan, PDA J Pharm Sci Technol 72, 105 (2017). [67] Zenodo, Manage files / storage quota documen- tation, https://help.zenodo.org/docs/deposit/ manage-files/ (2026), default limit 50 GB and 100 files per record; larger quota may be allo- cated/requested. Accessed August 2026. Supplementary Information for “Framework for an AI-Ready ARPES Community Database” (Dated: October 10, 2026) This Supplementary Information documents the basis for recommendations presented in the main text and sets out how they could be implemented. Section S1 describes the workshop, its source materials, and how community input is interpreted. Section S2 details the methods behind the bib- liometric survey of Fig. 2 in the main text. Section S3 records current data practice in our groups and the lessons of earlier curation attempts. Section S4 provides a compact technical account of why ARPES data require context (Table I of the main text). Section S5 proposes a provisional metadata specification and examines an example deposition. Section S6 compares our data ecosystem with other data ecosystems. Section S7 catalogs the AI applications presented in the main text, summa- rizes the lessons for foundation models, and proposes benchmark protocols. Section S8 consolidates our discussion on access, credit, hosting, and governance into an operational policy table, and names the elected steering committee. Section S9 lists goals, pilot deliverables, consensus statements, and unresolved decisions. Individual contributions to the discussion are described without attribution. S1. WORKSHOP METHODS AND INTERPRETATION OF COMMUNITY INPUT A. Format, participants, and sources The inaugural Conference on Artificial Intelligence & Electronic Structure was held at Stanford University on 4–6 August 2026 [1]. Day 1 consisted of 23 invited pre- sentations: two from domain experts in other fields (as- trophysics and protein modeling), five from condensed matter theorists and non-ARPES experimentalists, and sixteen from ARPES experimentalists at various univer- sity laboratories and synchrotron user facilities in North America, Europe, and Asia. Every speaker was asked two questions in advance: (Q1) what their scientific goal was and whether an ARPES database would help, and (Q2) what would make them want to deposit their data. The collected answers are given in Secs. S9 A and S8 A. Day 2 consisted of four structured discussion sessions (commu- nity end goals; contents, hosting, and governance; con- sensus building; action items) conducted on a shared on- line board, followed by a session to plan this paper. Four sources are used to assemble this Supplement: Day 1 slides shared with the organizers (8 of the 23 talks); Day 1 recap and Day 2 refresh slides prepared by the organizers; export of the Day 2 board; and the main text. We note where a talk is referenced only through the recap or through notes taken during the talks. Table S1 maps each section of this Supplement to the main text; we note that the steering committee elected at the workshop is listed in Sec. S8 E. B. How the Day 2 board is interpreted Day 2 discussions were structured around an online board on which comments would be placed on cards by participants and upvoted; the most upvoted comments became topics for immediate discussion. The board ex- port, generated on 5 August 2026, records 187 cards, 127 comments, 617 votes, 50 participants, and 48 vot- ers. Cards were anonymous and are not attributed here. We note three cautions regarding the vote counts quoted below. First, facilitators merged closely related cards, and summed their votes. A count on a merged card is therefore an aggregate of votes on its component state- ments (not a count of unique voters); we list the com- ponents where relevant. Second, votes were not exclu- sive: a participant could vote for several cards under one prompt. Third, the counts measure salience within a self-selected group of 48 voters. We therefore use the counts to indicate which issues mattered most to partic- ipants, not to establish consensus amongst the broader ARPES/condensed matter community. Figure S1 shows the most-voted cards under the substantive prompts. Throughout this Supplement, we sort all recommen- dations into three categories: (i) a workshop-supported principle: a position stated on the board or in talks that attracted substantial votes and no sustained objection; (i) an participants’ proposed implementation: a concrete mechanism we propose here or in the main text as a way of realizing such a principle, which the workshop did not itself specify; and (i) an unresolved option: a question on which participants expressed incompatible positions or none. The “Workshop status” column of Table I in the main text uses “broad agreement” in the sense of (i). TABLE S1. Where each section of this Supplement supports the main text. Section Main-text element supported S1[1]; Sec. IV (steering committee) S2Fig. 2 S3Sec. I B; Fig. 3 S4Sec. I A; Table I S5Sec. IV A; Table I (metadata, raw vs. pro- cessed) S6Sec. I A S7Secs. I B–C; Sec. IV C (benchmarks); Table I S8Sec. IV B; Table I (credit, access, misuse, host- ing, governance) S9Secs. IV C and V; Table I (unresolved points) 17 FIG. S1. Most-voted cards on the Day 2 discussion board, ar- ranged by prompt. Counts are aggregated votes (Sec. S1 B); merged cards appear as single bars with their component statements listed in Secs. S9 A, S5, and S8. Logistical cards (meeting timing, communication channels) are omitted. S2. BIBLIOMETRIC METHODS FOR FIG. 2 Figure 2 of the main text reports 7,188 ARPES publi- cations on quantum materials (1991–2025), 341,862 cita- tions to them, and 726 distinct materials named in their titles, together with publication counts for four other ex- perimental probes. This section records the procedure used to generate the numbers. Source and date. All counts were obtained from the Web of Science (Clarivate), current as of September 2026, with totals covering publication years 1991–2025. Publication set, panel (a). An “All Databases” topic search for “angle-resolved photoemission” and its spelling and acronym variants (ARPES; angle resolved photo emission; and related forms) was restricted by a keyword filter to quantum materials topics: correlated electrons and superconductivity, topology, quantum magnetism, and moiré and kagome lattices. Additionally, document types classed as preprints, Research Commons items, datasets, grants, and patents were excluded. The result contains 7,188 records. Citations, panel (b). Citations received by the records in (a) were binned by the calendar year in which they accrued rather than by the publication year of the cited paper, so that recent years are not suppressed by citation lag. The total count is 341,862. Materials, panel (c). Materials were identified by pars- ing the titles of records in (a). A material (system) is identified by its parent compound; distinct stoichiome- tries count separately (Bi 2 Sr 2 CuO 6 and Bi 2 Sr 2 CaCu 2 O 8 are two materials); doping and strain collapse onto the parent (La 2−x Sr x CuO 4 counts as La 2 CuO 4 at every x); solid solutions resolve onto their independently studied end members (FeSe 1−x Te x counts as FeSe and FeTe); and a film on a substrate is distinct from the bulk (FeSe/SrTiO 3 and FeSe are two materials). Because only titles are parsed, a paper whose material is named only in the abstract is not counted, and the 726 distinct ma- terials are a lower bound on the materials studied and an approximate count of those named. Other probes, panel (d). Publications per year were obtained for five probes under equivalent searches, each for the technique’s name as an exact phrase without acronyms and restricted by the same quantum-materials filter; the resulting ARPES curve holds 85% of the records in (a). “X-ray spectroscopy” covers x-ray absorp- tion, emission, and dichroism; resonant inelastic X-ray scattering is counted under X-ray scattering; X-ray pho- toelectron spectroscopy is not included. X-ray and neu- tron search strings match families of related techniques whereas the ARPES string matches a single technique, so cross-technique ratios are only indicative. Start year. All panels begin in 1991, the first year for which the Web of Science Core Collection indexes ab- stracts and author keywords. A title-only control search showed that the large apparent jump in topic-search counts between 1990 and 1991 is an indexing artifact, thus earlier counts—which reflect title wording only—are omitted. S3. CURRENT DATA PRACTICE AND LESSONS FROM EARLIER EFFORTS A. What our groups reported Table S2 summarizes what participating groups re- ported about their own data holdings and practices on Day 1. The entries are self-reports from talks, cover only the groups that brought up this point, and are illustrative (rather than a comprehensive survey) — the storage cen- sus called for in Table I of the main text would extend this across the rest of the ARPES community. We note three main observations. First, in one group which gave a full breakdown of their data holdings, the data volume that appeared in their papers was a small fraction of their archive, most of which consisted of alignment and spatial scans. Should this breakdown be common among the rest of the community, we anticipate that a shared archive should decide what to do with the remainder. Second, 18 even for recent data, the description of experimental ge- ometry needed to reconstruct cuts in momentum space (Sec. S4) is often not recorded: one group reported that from its own archive only the analyzer cylinder geometry is reliably available, while physical dimensions, resolu- tions, cleave photographs, and (for old data) manipulator matrices are not. Lastly, the facility-wide projections in the last row, of order one exabyte (EB) per year across all techniques at DOE light sources within five years, are not ARPES-specific and are included only to indicate the scale of the surrounding infrastructure. Mentions of other practices arose naturally and were brought up in the day’s recap: group data on Zenodo (two groups), FAIR-structured group data, and facility- level collection efforts at a US light source. The recap- concluded: that data exist but nobody is yet depositing into a shared community repository; that concerns about ownership, consent, credit, and incentives came up in nearly every talk; and that much data are in incompati- ble formats or in physical logbooks. B. Why earlier curation attempts did not persist A Day 1 talk listed reasons that earlier attempts at ARPES data curation failed: dependence on what one participant idiomatically referred to as “tender love and care” to maintain their database; no incentive for the de- positor to maintain their effort in the long run; an out- sized ambition to capture every modality (strain, flux, and so on) from the outset; no quality control for soft metadata; and a data-collection process detached from archiving. The same talk listed why reuse of existing data in later publications rarely succeeds: a difficult search for the right kind of data, asking journals, ask- ing authors “upon reasonable request,” checking DOIs, and asking for metadata. The talk’s principle, “make it dumb, then smarter” (to standardize basic ARPES mea- surements and reduction protocols first and peel bespoke experiments off the initial effort) is the origin of the main text’s insistence that the mandatory metadata core be small and that conversion happen on ingest, and of the sequencing in Sec. IV C. S4. CONTEXT DEPENDENCE OF ARPES DATA: A COMPACT TECHNICAL ACCOUNT Table I of the main text lists what must be preserved for each source of context dependence. Here we demon- strate this with the most common operations performed on ARPES data, the conversion of measured angles to momentum, and then distinguish measurement, process- ing, and interpretation. A. What momentum conversion requires An electron analyzer records counts as a function of kinetic energy E K and one or two emission angles. For a photoelectron leaving the surface at polar angle θ relative to the surface normal, the in-plane momentum is k ∥ = √ 2m e E K ℏ sinθ,(S1) and the binding energy follows from E B = hν− φ− E K with work function φ [2]. In Equation (S1), each sym- bol depends on recorded experimental context. E K must be referenced to the Fermi level, which requires either a reference spectrum (polycrystalline gold, or the sample itself) taken under the same analyzer settings, or the an- alyzer’s energy calibration. θ depends on the analyzer’s angular axis, the manipulator’s polar, tilt, and azimuthal angles and their sign conventions, any angular offset de- termined from the data, and the orientation of the sample on the holder. Out-of-plane momentum depends on pho- ton energy and an inner potential V 0 , which is itself a fitted quantity. The intensity at each (k, E B ) is modu- lated by photon energy, polarization, and light-incidence geometry (matrix elements), energy and angular reso- lution, and detector response (including nonlinearity at high count rates). Finally, whether a spectrum is in- terpretable at all depends on surface quality and how it degrades over time—cleave quality, time since cleaving, temperature cycles—which are the information least of- ten recorded. In summary, lost metadata limits the usefulness of a spectrum. A dataset that lacks the manipulator conven- tions can still be preserved and searched, but it cannot be placed in momentum space; one that lacks a Fermi- level reference can yield dispersions but not gap sizes; one that lacks the resolution cannot be used to extract line widths. Main text therefore asks (Sec. IV A) for a manda- tory core sufficient to interpret experimental geometry and reconstruct momentum, and metadata specification in Sec. S5 distinguishes what is required for admission to the archive from what is required for a particular scien- tific task. B. Measurement, processing, and interpretation Three layers should be kept distinct in any record. The measurement is the array of electron counts on its native axes (analyzer energy, angles) together with the instrument state. Processing comprises reversible or irreversible operations applied afterwards: Fermi level alignment, nonlinearity and transmission function cor- rections, normalization, angle-to-momentum conversion, symmetrization, and background subtraction. Interpre- tation comprises fitted quantities (peak positions, line widths, gaps, velocities) and model-dependent inferences such as a self-energy relative to an assumed bare band. The Day 2 board proposed that measurement metadata 19 TABLE S2. Data practices reported by participating groups and facilities on Day 1. Self-reported and illustrative; groups are not identified. The last row is a facility-wide projection across all techniques, not an ARPES volume. Group typeVolume reportedStorage and accessNotes Universitylab, mixed ARPES and x-ray scattering ∼ 7 TB total (2025); 50– 500 GB per ARPES ex- periment General-purpose repository (published); group drive or cloud folder (unpublished); one local PC and one RAID backup Mixed txt/dat/fits and nxs/h5/krx formats; acquisition under Lab- VIEW, Python, vendor software, and SPEC/EPICS; transfer by SFTP or Globus; search via date, keyword, and logbook; metadata completeness x-ray diffraction > scattering > ARPES; institutional cloud too expensive University lab, lab, synchrotron, and Tr-ARPES ∼ 3 TBInstitutional repository for publication and thesis data since ∼2015 Most volume consists of alignment and spatial scans; moving to reproducible data-to-paper notebooks; open analysis package with a typed metadata schema and analysis history Universitylab, micro-and transport-ARPES 5-D transport-ARPES set of ∼ 77,000 spec- tra; 22,800-point au- tonomous scan Zenodo, unrestricted reuse, citation only Training data for a published model are deposited but are not FAIR; metadata limited to the paper DOI Universitylab, long-running syn- chrotron program 26 years of archives—Offered to contribute the archive; only analyzer cylinder geometry reliably recorded in old data DOE Genesis Mis- sion project Corpus of 102 com- pounds; target 200+ To be publicly released, with a non-redistributable tier See Sec. S7 C Light-source com- puting group Projection of ∼ 1 EB per year across all DOE light-source techniques Facility archives; facility ML platform Beamline user data restricted to inter- nal training unless joint projects with co-PIs should be recorded separately from any post-processing (8 votes), with processing history stored inside the data file or alongside it. The board also agreed that data qual- ity is task dependent (for example, a spectrum may be “good for band mapping but not gap analysis”), that the archive should not impose a single quality score, and that data “bad” for one purpose carry information useful for another (a model trained to find a good spot on a sample needs realistic bad data). One card proposed “published” data as the one definitive marker, with subjective tags re- served for user comments and ratings. These positions underlie the “Raw versus processed data” and “Data qual- ity is task-dependent” rows of Table I; we note that the processing level of a record (raw, standardized, curated) is a statement about what has been done to it, not about its scientific reliability. S5. PROVISIONAL METADATA SPECIFICATION AND AN EXAMPLE DEPOSITION The main text proposes a compact mandatory core suf- ficient to reconstruct geometry and momentum, with ex- tensible free text annotations, and leaves the specific field list to the steering committee. Here we give a provisional specification (Table S3) assembled from Table I of the main text, the mandatory core list in Sec. IV A, and the Day 2 discussion, so that the pilot has a concrete start- ing point. We emphasize that this is the participants’ proposed implementation in the sense of Sec. S1 B rather than a community standard — we expect the steering committee to modify it in consultation with the rest of the ARPES community. A. Three metadata tiers Although the main text presents a two-tier distinc- tion of metadata, the Day 2 discussion deviated from this. The most-voted metadata card (13 votes) argued against standardizing the input side, because facilities’ formats have inertia, and for standardizing the output side through community-supported loaders into existing open analysis platforms; a comment proposed to gather representative files from all groups, report the current level of uniformity, and generate converters with group- specific recommendations, which another comment called “the only reasonable proposal which would not create too high of a barrier.” A second card (2 votes) proposed an agreed mandatory baseline plus an architecture for op- tional and future structured fields (for example, sample characterization, device parameters such as gate voltage, post-processing such as nonlinearity correction) with fu- ture dimensions added by the governing body. A third (6 20 votes) argued for a free-text field from the outset, because “we do not yet know what metadata will ultimately be important” — with a long comment arguing that a fixed schema shaped by early use cases can bias later searches, that free-text notes should remain as important as struc- tured fields, and that contextualization created during reuse should be contributed back as attributed, revis- able layers. Taken together these suggest three tiers: a compact structured core, structured extensions that are optional but typed when present (field, pressure, device state, calibrations), and free-text context. The second layer of the main text combines the latter two. Two further conventions were proposed on the board and are adopted in Table S3: a versioned schema, so that the conventions in force for a time-stamped dataset are unambiguous, with each group publishing its own no- tation alongside its data; and explicit “unknown,” “esti- mated,” and “not applicable” values, so that legacy data with incomplete metadata can be admitted without pre- tending to a completeness they lack. Two cards (2 votes each) stressed that the effort of adding metadata to old data “cannot be too high.” B. Existing tools The Day 1 recap described the main existing ARPES database—the NXmpes NeXus application definition as the standard, pynxtools as the conversion pipeline, and NOMAD as the hosting platform, with public datasets already hosted—and noted that adoption by a broad audience has been slow. The NeXus documentation distinguishes the general NXmpes definition for photo- electron spectroscopy from the ARPES-specific NXm- pes_arpes definition, which extends it and requires a defined ARPES coordinate system, the analyzer geome- try, a transformation chain for sample orientation, and a data block of one energy and two angular axes; the main text’s ref. [3] cites the latter. Table S3 is designed to be expressible in that definition. Two of the participants described in-house tooling that already implements parts of it: an open-source notebook-driven analysis package with a typed metadata schema and a recorded analysis history, and a converter from several instruments and beamlines to a single NeXus-based file together with an acquisition workflow in which standard operations (E– k cuts, Fermi-surface maps, domain and signal-to-noise optimization) are exposed as agent-callable tools and an automated check validates metadata before upload. A funding program that would support one to two staff to travel among groups building converters was also de- scribed. Under action items, a metadata dictionary with converters received 5 votes, with comments pointing to pynxtools and NeXus as the starting point. C. A deposition walk-through Phase 1 deliverables of Sec. IV.C in the main text (pre- serve native data; reusable converters; a minimal meta- data set sufficient for geometry and provenance; persis- tent identifiers) translate into a series of actions to take to upload a representative dataset of standard (equi- librium) ARPES data. Of these actions, a community data loader can perform a subset automatically. Ingest- ing the native files and any notes unchanged, converting signal, axes, and whatever instrument metadata the na- tive format carries into the schema (with absent fields set to “unknown”), validating units and the presence of core fields, and assigning a DOI, contributor records, and an access tier are all automatic once a loader ex- ists for the source format. The other two steps cannot be done by the depositor alone. Supplying the core fields that the native format lacks—geometry conventions, the Fermi reference, temperature, sample identity—requires the depositor, who should mark values recovered from notes or memory as estimated; for legacy data this is the main cost, and it is why two cards insisted that the ef- fort for old data “cannot be too high.” Reproducing a published figure from the standardized record, where the dataset underlies one, requires the depositor’s processing history and an expert comparison in which discrepancies are recorded rather than silently corrected. Later correc- tions create a new version with a change log rather than overwriting, so that the DOI remains citable. The vali- dation report and the log of manual interventions from these steps are the data that the “independent reuse” benchmark of Sec. S7 D needs. S6. LESSONS FROM OTHER DATA ECOSYSTEMS The main text (Sec. I A) argues that structural tech- niques built community databases first because their re- sults reduce to a compact, agreed representation, and that ARPES lacks one. Table S4 collects the precedents raised at the workshop, the lesson each offers, and where the analogy to ARPES breaks down. We comment on two precedents in more detail. The history of the Protein Data Bank [4, 5] was re- viewed on Day 1: deposition was voluntary from 1971, became a condition of publication only after a petition by senior structural biologists in the 1980s, and before that, scientists deposited because the data would never be lost, because they wanted errors caught, and for the public good; the archive survived four changes of dominant tech- nique and is itself biased toward what crystallography measures easily. The most-voted card under Should we do it? (15 votes)—a document recording the consensus of those present that the wider community can later sign— led to the consensus decision to write this paper. Nexus- LIMS [6], a laboratory information management system for shared-use electron microscopy, is closer to ARPES 21 TABLE S3. Provisional metadata specification for the pilot, organized by field group. “Core” fields are required for admission to the archive; “extension” fields are optional but structured when present; “context” is free text. Values may be recorded as known, unknown, estimated, or not applicable. The right-hand column indicates which fields a representative scientific task additionally requires, to make explicit that admission and task-readiness are different thresholds. The specification is the authors’ proposal and is to be mapped onto the NeXus NXmpes_arpes application definition [3] during the pilot; a .nxs file extension by itself does not establish a common meaning for its contents. Field group Core (required for admission) Structured extension (when available) Free-text con- text Required additionally for the task of. . . Identity and prove- nance Dataset identifier; sample identifier; contributors (in- cluding who measured and who grew the sample); in- strument or beamline; ac- quisition timestamp; schema version; conventions docu- ment Cleave or surface identifier linking measurements on the same surface; parent multi- dimensional dataset; related datasets; publication DOI Experimental intent; log- book excerpt Credit (sample source); leakage control in bench- marks (cleave and ses- sion identifiers) Signal and coordi- nates Intensity array on native axes; axis names and units; for each axis whether mea- sured or derived; energy scale type (kinetic or binding) Fermi-level reference spec- trum or calibration; derived momentum axes with the parameters used; detector- image coordinates —Gap extraction (Fermi reference); momentum- space comparison (de- rived axes with parame- ters) Experimental conditions Photon energy; polarization; sample temperature; manip- ulator angles and sign con- ventions; analyzer angular axis and light-incidence ge- ometry Energy and angular resolu- tion; analyzer lens mode, pass energy, slit; spot size; pressure; sample bias Alignment procedure Momentum reconstruc- tion (full geometry); linewidths and self- energies (resolutions) Sample and sur- face Composition or parent com- pound; crystallographic ori- entation if known Growth and preparation; cleave method and time since cleave; measurement position on sample; aging or spectral-quality evolution; reference XPS, LEED, or cleave photograph Cleave qual- ity remarks; anomalies noticed Cross-sample compari- son (preparation, time since cleave) Sample en- vironment Flag for any non-equilibrium condition Applied field, strain, cur- rent, optical excitation, gate voltage, with the instrument used to set and read each —Anyenvironment- dependent study ProcessingProcessing status (raw, stan- dardized, curated) and a link to the less-processed record Each operation with soft- ware, version, and param- eters: calibration, nonlin- earity and transmission cor- rections, normalization, in- terpolation, symmetrization, background Analysis nar- rative Reproduction of a pub- lished figure (full his- tory) Rights and release Access tier; rights holder or data-source type; permitted reuse Embargo date; dataset ver- sion and change log; usage statistics —Training-only use (per- mission to train recorded separately from permis- sion to redistribute) practice than the PDB: a co-op rather than a user fa- cility, with little enforceable top-down control, vendor- specific formats, and datasets abandoned over time; its design lesson was to build modularly on institutionally supported infrastructure and existing practices so as to survive changes underneath. The Day 2 board asked how astrophysics handles mis- use of public data by non-specialists, and one action item (6 votes) proposed including people from biology or as- trophysics with database experience to audit the pilot, with computer scientists experienced in large training corpora also suggested; the consensus prompt proposed inviting both groups to the next meeting. Notes from the Day 1 astrophysics talk record four uses of AI there— acquisition, emulating expensive processes, learning pos- teriors, and shared representations—with calibrated un- 22 TABLE S4. Data ecosystems raised at the workshop, the lesson each offers for ARPES, and the limitation of the analogy. EcosystemTransferable lessonLimitation of the analogy Protein Data BankVoluntary deposition can precede mandates if depositors gain preservation, error check- ing, and credit; a format that can evolve (Di- amond → PDB → mmCIF) lets the archive outlive techniques; transformative uses (Al- phaFold) arrived decades later and were not planned for A structure is a compact, validated result; an ARPES spectrum is a context-dependent measurement with no agreed reduced form, so the archive must retain original data, which the PDB did not need to Inorganic crystallog- raphy (ICSD) Deposition attached to publication as an easy step, with deep integration into analysis soft- ware; structure determination has a conven- tion for what is deposited Same as above; also, condensed-matter spec- troscopy has no deposition culture outside crystal and band structure Neutron scatteringNatively centralized collection and analysis at facilities, with standardized reduction pro- tocols for “basic” measurements; community analysis codes that grew from a standardized core ARPES is split between user facilities and home laboratories, with soft metadata (sur- face, cleave, charging) that scattering largely lacks Materials Project, NOMAD, arXiv API access for programmatic reuse; longevity as a public good; demonstration of productiv- ity and primacy through timestamps Computed data are regenerable and uni- form; experimental spectra are neither; arXiv curates documents, not multidimensional records Light-source knowl- edge graph [7] and medallion tiers [8] Link materials, publications, data, and meta- data so that a record is “queried with a spe- cific scientific question in mind”; refine data in tiers (bronze, silver, gold) with provenance between them A processing tier is not a quality grade: more processed does not mean more reliable, and task-specific quality must be recorded sepa- rately (Sec. S4) NexusLIMS [6]A co-op facility with no enforceable top-down control can still curate if the system is mod- ular and built on existing institutional infras- tructure and practices Electron microscopy data are images with vendor metadata; ARPES adds geometry and surface context that no vendor format carries completely Zenodo and institu- tional repositories Already used by several of our groups; DOIs and citation-only reuse work today Per-record limits (50 GB default, larger on request [9]); no ARPES-aware validation, search, or loaders; rate-limiting of bulk down- load certainty and full instrument fidelity as requirements, and a framing of theory-driven forward models versus data-driven foundation models as a bias-versus-variance trade-off. S7. AI USE CASES, BENCHMARK DESIGN, AND VALIDATION LIMITS A. What was presented Table S5 lists the AI applications presented or pro- posed at the workshop, their evidence status, and what each needs from a shared archive. The last column is our inference from the presentations and the board, not a statement by the presenters, and is intended to show that existing tools would benefit from the archive even before the existence of foundation models (main text Sec. I B, last sentence). One card on the board noted that many published ARPES tools did not release code, and an ac- tion item (3 votes) proposed compiling a list of AI tools for ARPES together with the standard computational and statistical tools that an agent would call as back- ends. B. Lessons from other foundation models A supplementary lecture on dataset construction drew lessons from computer vision, language modeling, and biochemistry. It argued that the bottleneck for foun- dation models in condensed matter “is the assembly of large datasets across experimental techniques — which is a political problem first, and only a technical problem second.” We summarize four lessons relevant to the main text. Distribution shift is not overfitting. Replication studies in image classification [21, 22] showed that a new test set built by the same procedure as the original produces an accuracy drop that is a distribution shift distinct from overfitting, that models keep their relative ranking un- der such shifts while humans are unaffected, and that 23 TABLE S5. AI applications in ARPES presented or proposed at the workshop. Evidence status: published (peer-reviewed or preprint result shown), presented (unpublished result or prototype shown in a talk), proposed (described as a plan or raised on the board). The last column is the authors’ inference. ApplicationStatusWhat was shownWhat it needs from the archive Denoising of low-count spec- tra, including uncertainty estimates PublishedRecap only [10, 11]Paired low- and high-count mea- surements with resolution metadata; held-out materials Correction of detector non- linearity PresentedRecap onlyRetained calibration data per instru- ment and session Feature extraction, disper- sion tracking, phase classifi- cation PublishedRecap only [12–15]Standardized axes; task-specific quality flags Convolutional autoencoder representation of spec- tra [16] Published256×256 spectra compressed to a 512-dimensional latent; com- pression, denoising, clustering; representation preserved across materials; training data on Zenodo without metadata Spectra from many materials on a common image grid; material and condition labels to test what the la- tent encodes Self-supervised latent space for x-ray scattering [17], pro- posed for ARPES Published (scattering); proposed (ARPES) 83.6-million-parameter condi- tional VAE on 1.5 million im- ages; one latent space serves denoising, stopping prediction, anomaly flagging at ingest, similarity search A large unlabeled corpus; ingest-time hooks so that quality flags are com- puted on deposit Autonomousmicro- ARPES [18] PublishedGaussian-process-guided search over position and angle; 22,800-point example Spatial maps with positions retained; records of the acquisition decisions Beam-spot quality scoring; sample-edge finding; acqui- sition loop with simulator and on-the-fly analysis PresentedRecap and notes onlyRealistic “bad” data labeled as such; intent metadata distinguishing opti- mization scans from measurements Agentic laboratory workflow with vision-language model and metadata validation PresentedConverter to NeXus; stan- dard operations exposed as agent tools; automated meta- data check before upload A schema to validate against (Ta- ble S3) Domain-adversarial bridge from simulated to measured spectra [19] Published“Train with theory, deploy on experiment” Simulated records flagged as such; matched experimental records Fast spectral simulator (10 ms per spectrum) PresentedPrototype; initial CNN tests; related effort of [20] Experimental data to measure the domain gap against Self-energy prediction from structure and DFT, trained on ARPES Proposed, in progress See Sec. S7 CRaw spectra over wide k ranges with full conditions; extracted self- energies where available Search for topological invariants;cross-modal “quantization-proximity” search ProposedProgram combining spin- and time-resolved ARPES, STM/STS, and nonlinear optics Links from ARPES records to STM and optics records on the same ma- terial Similarity search, next- experimentsuggestion, automatic characterization (“electronic forest”) ProposedEach material carries its CIF and measured Fermi surface; a generative model “trained on the forest, not on papers” Material identity and crystal struc- ture attached to every record; momentum-space products Standard AI agent on the acquisition computer Proposed (board,6 votes) Context-dependent notes dur- ing beamtime, capturing deci- sions A free-text context layer that tools can write to robustness to synthetic perturbations does not transfer to natural shifts. The questions this raises for ARPES are: which shifts to expect (between instruments, be- tween measured-easily and measured-rarely systems, be- 24 tween techniques) and whether multimodal or contrastive training across techniques mitigates them. This is the ba- sis of the main text’s statement that robustness depends on breadth and quality of data. Data quality is operational. In the DataComp bench- marks [23, 24], “quality” is defined by downstream per- formance rather than by human judgment, which tends to overvalue polished data and undervalue diversity; the “bitter lesson” [25] makes the same point for hand-built priors. For ARPES this means an instinctive judgment of “good data” should not gate deposition, whichiswhat the board concluded independently (Sec. S4). Synthetic data are useful but limited. Synthetic data can supply scale when real data are scarce, but they propagate the simulator’s assumptions and, when models train on their own outputs, risk model collapse [26, 27]. The lecture’s own suggestion was to pre-train on spec- tra from DFT, DMFT, or tight-binding models across as many systems as possible and fine-tune on measured data; the self-energy project of Sec. S7 C follows the same sequence. What remains open is the proportion and fi- delity of synthetic data: what fraction of pre-training is synthetic, how faithful the simulator must be to ma- trix elements and instrument response, whether simu- lated spectra enter the archive itself (one card proposed adding them, explicitly labeled, especially for systems be- yond DFT), and how much experimental supervision is needed before predictions on unmeasured materials can be are all open topics. Table I of the main text records the agreement that simulated data be flagged and that measured data anchor validation. Data attribution could inform credit, but is not yet a credit system. Methods that estimate the contribution of individual training examples to a model’s output— Data Shapley [28], influence functions [29], datamod- els [30, 31]—were presented as a way to quantify the value of specific datasets so that “researchers’ hard-won data do not just disappear into a black box,” and to locate gaps where data should be taken. These methods are com- putationally demanding, model-specific, and unvalidated as measures of scholarly contribution; we regard them as an exploratory addition to be used alongside the trace- able dataset manifests and contributor records proposed in Sec. S8. C. A worked example: self-energy prediction trained on ARPES One presentation described a DOE Genesis Mission Phase I project combining ARPES, oxide molecular- beam epitaxy, correlated-electron theory with machine learning, and micro-ARPES at a national-laboratory beamline. It is the most concrete existing plan to use community ARPES data as training data. The goal is to predict the self-energy Σ(k,ω) from crystal structure and DFT band structure alone, using ARPES spectra in supervised learning. The corpus con- sists of raw or published spectra placed on a common (k, E) grid together with CIF and DFT entries; it held 102 compounds at the time of the workshop, with a tar- get of 200 or more, 10 held out for testing. This num- ber is the project’s assembled corpus of compounds with training-usable data; it should not be confused with the 726 distinct materials named in ARPES publication titles since 1991 (main text Fig. 2), most of which exist only as figures, and the presentation’s point was that “most pub- lished ARPES lives inside figures, and vision models are bad at them.” The model is a small residual U-Net, pre- trained on simulated spectra and then fitted to the mea- sured corpus, with physical constraints imposed: a non- negative quasiparticle scattering rate (with the retarded convention, Γ = − Im Σ R ≥ 0), Kramers–Kronig con- sistency between real and imaginary parts, and crystal symmetry. The planned test is to grow a compositional- gradient wafer of a correlated material never measured by ARPES (e.g., La 1−x Sr x VO 3 across the Mott transi- tion) and to measure hundreds of compositions by micro- ARPES with a spot below 10 μm, comparing with pre- diction. In this example project, it is important that what quan- tities measured, fitted, and inferred should be kept dis- tinct. The archive itself holds measured spectral inten- sities, while dispersions and line widths are fitted from momentum or energy distribution curves, and the project noted that the model itself must decide which analysis ap- plies. The self-energy is then inferred relative to a bare band that is never measured and is taken from DFT, an approximation with known failure modes in correlated systems; the inferred Σ is further affected by matrix ele- ments, resolution, overlapping bands, k z broadening, and the limited energy window of a given measurement, and the project’s initial assumption of a local (momentum- independent) Σ “will be bad for certain materials” such as the cuprates and the orbital-selective iron chalcogenides. Different groups may extract different self-energies for the same material, which is part of what the model must absorb. Two levels of participation were offered: public release, in which processed data are used for training and then published in the released corpus; and non-redistributable, in which data are used for training but not released, al- though measurement metadata are. The trained model is to be released in either case. This separates permis- sion to train from permission to redistribute, which is the distinction adopted in Table S7. D. Benchmark protocols and the leakage problem The main text names three benchmark tasks for the pilot—cross-instrument dispersion extraction, uncertainty-aware denoising, and cross-material similar- ity search—with held-out experimental test sets and con- ventional analysis as the baseline, and adds that useful- ness should be judged by whether outside groups can find 25 and reuse the data. Table S6 shows the authors’ propos- als on how each would be evaluated. It is important to remember that spectral cuts from the same sample, the same cleave, the same measurement ses- sion, or the same parent multidimensional dataset are not independent, and a model that has seen one will perform unrealistically well on the others. Held-out sets must therefore be defined at the level of material, sample, or instrument, not spectrum; the cleave and parent-dataset identifiers in Table S3 exist to make this possible. Spec- trum counts therefore overstate the number of indepen- dent materials, therefore the corpus sizes in Sec. S7 C should be read with that in mind. S8. ACCESS, ATTRIBUTION, HOSTING, AND GOVERNANCE This section summarizes the Day-2 discussion on how the archive would be used and run. It supports Sec. IV B of the main text and the “Data misuse,” “Credit and attri- bution,” “Access, ownership, and facility policy,” “Hosting and scale,” “Participation incentives,” and “Governance and maintenance” rows of Table I. The policy choices are collected in Table S7; the discussion that led to them follows. A. Conditions for contributing Day 1 answers to Q2 (What would make you want to deposit your data?) were: • An explicit access, reuse, and attribution policy, with guidelines for poor legacy metadata, • Settle ownership, consent, and credit before pool- ing; lower the threshold and add incentives (reuse projects, funding, publication mandates), • Governed, curated data with a semantic layer of intent and provenance, • Limited, project-specific collaboration rather than open-ended pooling, • Standardized labels for material, doping, and tem- perature, • Facility beamline data for internal training only, with sharing beyond that through joint projects, • FAIR HDF5 at acquisition, with published or un- used data merged into a repository, • “Unrestricted deposit already works for me: no per- mission needed, just cite the paper”, • And “the database simply needs to exist; model quality is capped by dataset diversity.” On Day 2, the most-voted conditions were: • Citation credit for reuse (17 votes, merged from four cards: citation for reuse in publication with whole-corpus training excepted, • Credit to the students and postdocs who took the data, • Inclusion of sample growers, • Explicit acknowledgment in the main text of pa- pers) and starting with published data (16 votes: “let’s start with something simple that gets trac- tion”, • “Phase 1, published data; Phase 2, unpublished later”). A private section with tiered access received 6 votes. Talking directly to the major journals to encourage or require deposition received 5 votes but drew objections (forcing commitment at the start is hard to maintain, and much good ARPES is published elsewhere) and we recorded it as unresolved. Per-access consent (4 votes) was the most-commented card and the comments were mostly opposed: posting carries the understanding that someone may download; whole-corpus AI cannot work under per-access consent, so “if we hope to generate new knowledge in this way, we have to be quite open”; gate- keeping could be a depositor option, “but if the majority adopt this protocol, the database loses its purpose”; noti- fication without permission would still be valued. Cards under other prompts added that a converter from famil- iar text files “would greatly encourage adoption” (4 votes) and that the pilot should “quickly demonstrate, even with a simple example, what people can actually do with the database” (3 votes). One Day 1 talk gave the most specific incentive list: recognize and fund projects based on data reuse; confer- ence sessions, fellowships, and data-mining hackathons; counting a group’s data effort toward beamtime proposal ratings; and, as enforcement, publication requirements. It also listed what the effort needs (data, computing, stor- age, full-time staff) and what a depositor might receive (investment, beamtime). B. Credit The credit card under Concerns (15 votes, 14 com- ments) produced the longest thread on the board. The distinction that emerged (and Table I of the main text adopts) is between credit for identifiable reuse of a few datasets in a paper (for which a DOI and a required cita- tion suffice), and credit for whole-corpus training, “where individual accesses are much less the main point.” Mech- anisms proposed for the former are: an ARPES-specific Zenodo-like service; a DOI per dataset; a shared credit policy modeled on large high-energy-physics collabora- tions; a depositor-selected reuse license. Questions left open were: who is credited (experimenters, PI, growers); 26 TABLE S6. Proposed evaluation of the benchmark tasks named in Sec. IV C of the main text. Authors’ proposals. TaskEvaluationSafeguard Cross-instrument dis- persion extraction Error in band position and Fermi velocity against conventional MDC/EDC fitting on the same data; fraction of cases in which the reported uncertainty interval covers the conventional value Hold out entire instruments or laboratories, not spectra; report performance separately for in-distribution and held-out instruments Uncertainty-aware de- noising Preservation of gap magnitudes, line widths, and weak features against an independent higher-count measurement of the same sur- face; calibration of reported uncertainties Test for introduced features and for system- atic distortion of line shapes; never evaluate against a denoised reference Cross-material simi- larity search Retrieval of spectra of the same material or the same spectral feature across changes of photon energy, temperature, and instrument Test whether similarity tracks physics or in- strument identity by querying with the same material measured on different instruments Independent reuseTime and assistance an outside group needs to locate a dataset and reproduce a pub- lished dispersion or figure from it Log every missing metadata and manual in- tervention; these logs feed back into the core-field list Automatic metadata capture (Phase 2) Fraction of core fields populated without manual entry during an ordinary beamtime at the demonstration site Compare with the fraction populated for legacy data of the same instrument what credit means for a student (a citation or a CV line); who is “first” (to measure, upload, publish, or conceive); and how deposited data become citable in scholarly in- dices. On primacy, one comment proposed that the de- posit timestamp establishes who measured first, while priority for an interpretation continues to rest on publi- cation or preprint. One comment cited a pending lawsuit by a news publisher over training use of its articles as a caution. C. Misuse and quality The second most-voted concern (19 votes) was misuse by non-specialists: “strangers use data in an unautho- rized way, producing questionable science.” Remedies proposed in comments ranged from education (a visual- izer that applies the common corrections, bridging data with documented analysis tools, peer review as the ex- isting gatekeeper) to gated access (registered users only, mandatory discussion with the dataset creator, owner no- tification). The observation that already-published data are already public narrowed the concern to unpublished data. Table I records the preference for education and reproducible analysis over approval gates as broad agreement; the gating proposals were individual posi- tions. Data quality and vetting (12 votes, 10 comments) is treated in Sec. S4. Lower-voted concerns included: who can claim to be first (3); whether success with lan- guage models will “put ARPES experimentalists out of business” (2); conflicting data from different groups and inconsistency between runs (2 each); the activation bar- rier of using another group’s data under different norms (1); biases in dataset weighting (1); and how to define the boundary of the ARPES community, given non-specialist beamtime users and adjacent techniques. D. Hosting The most-voted concern overall (24 votes, 15 com- ments) merged maintenance, management, and a com- ment on “moderation and oversight, so that [the ecosys- tem] doesn’t die and become obsolete in a couple years.” Under Who should host?, no positive option received strong support; the most-voted card (8 votes) was a negative preference, “not owned/hosted by a single fed- eral agency/company,” and one comment warned that national-laboratory hosting “may be dangerous given the current situation.” Options raised included: pooled resources to hire professionals versus rotation among groups (rotation received 4 votes but comments noted unequal manpower and weak enforceability); mirror sites at laboratories and universities (2 votes); decentralized or co-hosted across institutions (2); a few pilot sites first; existing services such as Zenodo (“not Google”) subject to per-record limits and rate-limiting of bulk downloads; national computing and data resources (DOE model-training consortia, the American Science Cloud, the American Data Cloud), whose suitability was not evaluated. Two comments observed that database ef- forts are already under way in some countries, so that a single archive may be impossible for policy reasons and a superstructure connecting parallel efforts may be un- avoidable. One card asked that storage need and cost be defined before a hosting model is chosen, with a census in which each group reports what it would submit today; the survey questions proposed for it are in Sec. S9 B. The main text’s recommendations—a storage census, several independent pilot sites, and designing for migration and 27 TABLE S7. Operational policy choices the pilot must test, with the options raised on the Day-2 board. Status follows Sec. S1 B: WP, workshop-supported principle; AI, authors’ proposed implementation; UO, unresolved option. ChoiceOptions raisedWhat the pilot should testStatus Public downloadAnonymous download; registration required (“a minimal gateway to stop bot scraping”); per-access notification of the depositor; per- access permission Whether registration plus notifi- cation satisfies depositors without deterring reuse WP (open with regis- tration); UO (per-access permission) Restricted accessProject-specific collaboration with clear rules; joint projects with co-PIs for facil- ity user data; invitation-only registration at first Whether a restricted tier attracts data that would otherwise not be deposited WP (tiers) Training-only use Data used to train a released model but not redistributed, with metadata released (Sec. S7 C) Separate permissions for (a) training, (b) redistributing the data, (c) releasing model weights; whether depositors use the tier AI EmbargoPrivate per-group staging with a “go public” control (10 votes); a maximum embargo of 3 or 5 years so that data are not forgotten; delay to defuse competition Whether staging raises deposition of unpublished data; the embargo length WP (staging); UO (length) Correction and versioning Versioned schema; corrected datasets as new versions with change logs; who may correct Whether versioning preserves citability AI Contributor credit Dataset DOI; required citation for identifi- able reuse (17 votes); creator records nam- ing who measured and who grew the sample; acknowledgment in the main text of papers using the data; facilities credited for infras- tructure, not interpretation Whether citation of datasets ap- pears in practice; whether student and postdoc contributors are find- able WP Corpus-level credit Citation of the database as a whole; man- ifests listing every dataset used to train a released model; usage statistics shown to de- positors; data attribution as an exploratory measure (Sec. S7 B) Whether a manifest and usage statistics are regarded by depos- itors as adequate credit for whole- corpus training UO Commercial and industry use Whether commercial entities may train on the data; whether industry funding would entitle their models to the data (15 votes, no resolution) To be expressed through the rights metadata of Table S3 once a posi- tion is reached UO Legal ownershipRights depend on institution, grant, facil- ity, and country (11 votes); review by data- source type; “should we involve an actual lawyer” A per-source-type rights review before scale-up WP mirroring—follow from this. E. Governance Under Who should be responsible?, the most-voted card (6 votes) was a yearly or biennial meeting like the present one; others proposed a rotating committee, a committee of four to six whose groups also maintain the database during a two-to-three-year tenure, inclusion of students and postdocs “who really get their hands dirty with the AI work,” and a request that roles, responsibilities, vot- ing, and tenure be defined. Responsibilities suggested: access-control and quality-control policy (“representing the community for decisions, not doing all the work”; 3 votes); exploring funding for hosting; organizing annual meetings. Structural suggestions with votes: draw from both national laboratories and universities, with both theorists and experimentalists, and a chair or co-leads with experience of both ARPES and databases (5); in- clude the computing and AI-for-science side (4); co-lead by two or three people combining experiment, data, and AI (4); an international advisory committee alongside a domestic executive committee (4). One card argued for defining roles and drafting the document before selecting people, so that the broader community can weigh in. Nominations were collected through a form and on the board; we do not reproduce the nominations or their vote counts. An initial steering committee was estab- lished by anonymous vote of participants before the work- 28 shop closed. Its members are Tanny Chavez (Advanced Light Source), Andrea Damascelli (University of British Columbia), Yu He (Yale University), Chunjing Jia (Uni- versity of Florida), Takeshi Kondo (University of Tokyo), Laurenz Rettig (Fritz Haber Institute), Eli Rotenberg (Advanced Light Source), Kyle M. Shen (Cornell Uni- versity), Zhi-Xun Shen (Stanford University), and Inna Vishik (University of California, Davis). The commit- tee’s remit is that stated in Sec. IV of the main text: to coordinate follow-up work, engage the broader commu- nity, and develop solutions to the unresolved technical, policy, and governance questions listed in Sec. S9 D. Its term, rotation, and eventual confirmation by the wider community were not settled at the workshop. S9. PILOT DELIVERABLES, CONSENSUS STATEMENTS, AND UNRESOLVED DECISIONS A. Goals and definitions of success Day 1 answers to Q1 (What is your goal?) were: • Seed an ARPES foundation model by self- supervised pre-training on curated facility data, • A self-driving laboratory that understands ARPES and picks the next measurement, • A foundation model for quantum matter that pre- dicts regimes nobody has measured, • Robust denoising of low-count trARPES, which needs diverse, realistic training data, • Causal-discovery AI linking growth, spectra, and properties, • Rescue three decades of beamline data and restart AI-friendly with a facility upgrade, • Preserve group data and enable real reuse, with FAIR metadata and provenance from data to pa- per; repeat biology’s path by building the curated corpus first, • A theorist-accessible, analysis-ready database fed automatically by the beamline, • Extract Hamiltonian parameters directly from spectra, then automate it with agents; automate “basic” ARPES so that a standardized archive builds itself during measurement, • Compact learned representations for 5-D, terabyte- scale datasets, • And an inference approach to the trARPES energy–time resolution trade-off. The recap grouped these as (1) a transferable founda- tion model, (2) closing the acquisition loop, and (3) new insight from pooled past data, which correspond to the long-, intermediate-, and near-term timescales of the main text. Several of these are aspirations whose assumptions and validation remain to be specified; the benchmark protocols of Sec. S7 D are a first step towards this. On the board, the most-voted goal (21 votes, merged from four cards) was to organize one’s own group’s data in a FAIR-compatible manner within months regardless of the workshop outcome, build a converter to a standard searchable format, build both a unified dataset and a gen- eralizable prescription for experimental datasets across condensed matter, and at minimum decide a format, a location, and a policy to replace journals’ ad hoc up- load rules. Making use of unpublished and “failed” data received 10 votes, and a large corpus for training and benchmarking 8. Definitions of success, in order of votes: a physics insight from the combined data that human researchers had overlooked (15 votes); uptake beyond ARPES specialists, with the effort boosting rather than killing the community (12); the database becoming the standard for all ARPES groups (11); experimental data becoming the “electronic ID” of a material, compared sys- tematically with DFT, DMFT, and QSGW (11); reusable benchmark datasets analogous to the standard test im- ages of computer vision (7); shared, adaptable acquisi- tion and analysis scripts (4); validation or refutation of conclusions from other data during peer review, and a database so easy to use that no group can plausibly claim deposition is unfeasible (3); and a quantifiable success metric (3). One Day 1 talk called for a “poster child” demonstration—an “AlphaFold moment”—and the Day- 2 refresh posed the same question. B. Action items and the status-quo survey Action items with corresponding vote counts are listed here: • Include database-experienced people from biology or astrophysics to audit the process (6 votes), • A metadata dictionary with converters (5), • A list of AI tools for ARPES (3), • Clarify legal ownership by data source (3), • A democratic vote on the metadata format (3), • Survey all groups’ data files and compare fields (2), • Each group publishes its conventions with its data (2). Without votes: estimate each group’s upload volume and server cost; define quantifiable success metrics and 29 explicit incentives; investigate national data-cloud re- sources; a small committee with defined roles and term limits; a literature search on what other fields have done; start with old published data. Among next steps, set- ting up a test server and uploading the easiest files first received 7 votes, with comments to check existing repos- itories first and to review the literature before fixing a schema; a proposal for a digital-twin framework of in- strument geometry and k-space coordinates was shelved for later. Questions proposed for a community status-quo survey are: each group’s ARPES data volume in TB; the split of time between user-facility and laboratory ARPES; a ranking of the biggest challenges (infrastructure, incen- tive, technological); and representative data files, con- tributed by link, for a longitudinal comparison of meta- data fields. These questions are the template for the storage census in Table I of the main text, and their answers would extend Table S2 across the community. C. Scope and consensus statements A dedicated prompt asked whether the database should hold published data or any ARPES data with good metadata: the latter received 5 votes and the for- mer 1, while a card proposing separate purpose-specific databases received none and three objections (hard to maintain; one database with intent flags has better longevity; the separation is itself a bias). Together with the 16-vote “start with published data” card (Sec. S8 A), this suggests that published data come first as a sequenc- ing decision, with the eventual scope being any ade- quately described data in a single archive with intent flags. Cards under Consensus were: another meeting next year (12 votes), in August; at least one paper describ- ing the findings and plans (3); a first committee to take the next step (2); and invitations to computer scientists and to PDB or AlphaFold people. A six-point plan (2 votes)—work toward a database; lead by the working group but bring the broader community together; a white paper as the first step to identify stakeholders; a few database sites, connected or separate, usable for bench- marking; a community-approved steering committee with terms and governance; and eventually funding, a sustain- able platform, and policy—closely tracks the program laid out in Secs. IV C and V of the main text. D. Unresolved decisions Here we list the questions that the workshop left open, and that the steering committee and the pilot are to re- solve, are collected here; they correspond to the “unre- solved” and “open in detail” entries in Table I of the main text. 1. The content of the mandatory metadata core, the level of details required, and whether imaging and time-of-flight analyzers share a schema (Sec. S5). 2. Per-access permission versus open download with registration and notification (Sec. S8 A). 3. Whether to seek journal deposition mandates now or let the archive earn adoption (Sec. S8 A). 4. Credit for whole-corpus model training, beyond manifests and usage statistics (Secs. S7 B and S8). 5. Commercial and industry access (Table S7). 6. The proportion and fidelity of synthetic data in pre- training, and whether simulated spectra enter the archive (Sec. S7 B). 7. The permanent hosting model and host, after the storage census and pilots (Sec. S8 D). 8. The steering committee’s term, rotation, and con- firmation by the wider community (Sec. S8 E). 9. The boundary of the “ARPES community” for deposit, access, and voting, given non-specialist beamtime users and adjacent techniques (Sec. S8). [1] AI & Electronic Structure Workshop (2026), https:// aies-workshop.su.domains/ [Accessed: 2026-08-10]. [2] A. Damascelli, Z. Hussain, and Z.-X. Shen, Reviews of Modern Physics 75, 473 (2003). 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