[{"acknowledgement":"We are grateful to K. Irwin for illuminating discussions, and M. Schleier-Smith, M. Kasevich, J. Hogan, N. Rapidis, M. Fedderke, A. Geraci, G. Gratta, D. Schuster, D. Budker, and A. Sushkov for very valuable conversations. O.H. acknowledges support by the Institute of Science and Technology Austria (ISTA). A.A., S.D., and M.G. acknowledge the hospitality provided by ISTA, where part of this work was being completed. A.A., M.G., and O.H. acknowledge the hospitality provided by the Leinweber Institute for Theoretical Physics at Stanford, where part of this work was being completed. S.D. acknowledges support by NSF Grant No. PHY-2310429 and the Gordon and Betty Moore Foundation Grant No. GBMF7946, and Perimeter Institute and its hospitality. Research at Perimeter Institute is supported in part by the Government of Canada through the Department of Innovation, Science and Economic Development and by the Province of Ontario through the Ministry of Colleges and Universities. A.A. is grateful for the support of the Stavros Niarchos Foundation.","oa":1,"external_id":{"arxiv":["2508.20520"]},"supplementarymaterial":"yes","article_type":"original","article_processing_charge":"No","year":"2026","date_created":"2026-10-04T22:01:57Z","title":"Superradiant interactions for relic detection with entangled nuclear spins","date_updated":"2026-10-12T08:36:40Z","author":[{"last_name":"Galanis","first_name":"Marios","full_name":"Galanis, Marios"},{"last_name":"Hosten","id":"4C02D85E-F248-11E8-B48F-1D18A9856A87","first_name":"Onur","orcid":"0000-0002-2031-204X","full_name":"Hosten, Onur"},{"last_name":"Arvanitaki","first_name":"Asimina","full_name":"Arvanitaki, Asimina"},{"full_name":"Dimopoulos, Savas","last_name":"Dimopoulos","first_name":"Savas"}],"abstract":[{"lang":"eng","text":"We recently showed that macroscopic nuclear spin ensembles prepared in coherent spin states can dramatically enhance the interaction rates of weakly interacting cosmic relics, such as dark matter and the cosmic neutrino background, through collective quantum effects analogous to Dicke superradiance, where the deexcitation and excitation rates scale as the square of the number of spins 𝑁2. We thus coined these processes superradiant interactions. In this paper, we propose a protocol to realize this enhancement and boost the discovery potential for such relics. We show how concepts from quantum optics can be adapted to nuclear spins coupled to superconducting circuits, enabling high-sensitivity systems. The spins are first initialized into a coherent spin state via a 𝜋/2 Rabi pulse from the ground state. When the circuit is sufficiently detuned from resonance, the spin-circuit interaction implements a squeezing Hamiltonian. Because squeezing must outpace spin relaxation and dephasing, the protocol favors macroscopic ensembles and high-quality superconducting circuits. During this squeezing phase, the standard quantum variance is reduced by up to 4.8 orders of magnitude, equivalent to 48 dB of squeezing, for circuits with quality factors 𝑄∼10^8–10^9. The signal imprinted on the spins during the squeezing protocol can be magnified by further utilizing the squeezing interactions, easing the requirement for shot-noise-limited readout. This protocol has the potential to significantly accelerate axion and dark photon dark matter searches and extend the reach of existing axion experiments to probe QCD axion-nuclear spin couplings. More broadly, it paves the way for detecting coherent inelastic interactions from other cosmic relics, most notably the cosmic neutrino background, and establishes nuclear-spin-based systems as a class of quantum, ultra-low-threshold detectors."}],"arxiv":1,"researchdata_availability":"upon request","article_number":"063714","day":"01","citation":{"ama":"Galanis M, Hosten O, Arvanitaki A, Dimopoulos S. Superradiant interactions for relic detection with entangled nuclear spins. <i>Physical Review A</i>. 2026;113(6). doi:<a href=\"https://doi.org/10.1103/Z2D9-4GV6\">10.1103/Z2D9-4GV6</a>","ieee":"M. Galanis, O. Hosten, A. Arvanitaki, and S. Dimopoulos, “Superradiant interactions for relic detection with entangled nuclear spins,” <i>Physical Review A</i>, vol. 113, no. 6. American Physical Society, 2026.","apa":"Galanis, M., Hosten, O., Arvanitaki, A., &#38; Dimopoulos, S. (2026). Superradiant interactions for relic detection with entangled nuclear spins. <i>Physical Review A</i>. American Physical Society. <a href=\"https://doi.org/10.1103/Z2D9-4GV6\">https://doi.org/10.1103/Z2D9-4GV6</a>","ista":"Galanis M, Hosten O, Arvanitaki A, Dimopoulos S. 2026. Superradiant interactions for relic detection with entangled nuclear spins. Physical Review A. 113(6), 063714.","chicago":"Galanis, Marios, Onur Hosten, Asimina Arvanitaki, and Savas Dimopoulos. “Superradiant Interactions for Relic Detection with Entangled Nuclear Spins.” <i>Physical Review A</i>. American Physical Society, 2026. <a href=\"https://doi.org/10.1103/Z2D9-4GV6\">https://doi.org/10.1103/Z2D9-4GV6</a>.","mla":"Galanis, Marios, et al. “Superradiant Interactions for Relic Detection with Entangled Nuclear Spins.” <i>Physical Review A</i>, vol. 113, no. 6, 063714, American Physical Society, 2026, doi:<a href=\"https://doi.org/10.1103/Z2D9-4GV6\">10.1103/Z2D9-4GV6</a>.","short":"M. Galanis, O. Hosten, A. Arvanitaki, S. Dimopoulos, Physical Review A 113 (2026)."},"intvolume":"       113","volume":113,"das_tickbox":"1","date_published":"2026-06-01T00:00:00Z","status":"public","issue":"6","corr_author":"1","quality_controlled":"1","doi":"10.1103/Z2D9-4GV6","publication_identifier":{"eissn":["2469-9934"],"issn":["2469-9926"]},"fulldoi":"https://doi.org/10.1103/Z2D9-4GV6","OA_type":"green","department":[{"_id":"OnHo"}],"OA_place":"repository","publication":"Physical Review A","language":[{"iso":"eng"}],"user_id":"2DF688A6-F248-11E8-B48F-1D18A9856A87","publication_status":"published","main_file_link":[{"url":"https://doi.org/10.48550/arXiv.2508.20520","open_access":"1"}],"dataavailabilitystatement":"The data that support the findings of this article are not publicly available. The data are available from the authors upon reasonable request.","publisher":"American Physical Society","type":"journal_article","month":"06","_id":"23057","oa_version":"Preprint","scopus_import":"1"}]