Kinetically Constrained Cavity QED: From Blockaded Ferromagnetism to Long-Range Quantum Scars
Year: 2026
Type: article
Abstract: Rydberg–cavity systems are emerging as promising platforms for quantum simulation and quantum information processing. These hybrid architectures combine two complementary interaction mechanisms: cavity photons mediate collective long-range couplings, while Rydberg excitations generate strong short-range interactions. Together, they offer a setting for engineering many-body phases characterized by a hierarchy of interactions across widely different length scales. In this work, we introduce a minimal and scalable model for such systems. Focusing on the strong Rydberg blockade regime, we restrict the Hilbert space to the subspace enforced by the blockade, yielding a kinetically constrained long-range model in one spatial dimension. This approach both captures the physics of Rydberg–cavity experiments in the regime of strong Rydberg interactions and provides a conceptually transparent framework for studying the interplay of long-range and short-range interactions. At equilibrium, in addition to paramagnetic and Néel-ordered phases, the system supports a blockaded ferromagnetic/superradiant phase, distinct from the conventional superradiant phase. Out of equilibrium, we identify long-range quantum many-body scars, which are atypical nonthermal eigenstates that evade the eigenstate thermalization hypothesis, and giving rise to slow entanglement growth. In contrast to the linear-in-time entanglement growth characteristic of short-range scarred models, these long-range scars exhibit logarithmic entanglement dynamics. Our results establish a minimal yet versatile framework for Rydberg–cavity systems, and provide a stepping stone for future theoretical and experimental studies of this frontier platform in quantum many-body physics.
Source: PRX Quantum
DOI: 10.1103/586v-sxqr
Institutions: Johannes Gutenberg University Mainz, University of Konstanz, Institució Catalana de Recerca i Estudis Avançats, Institute of Photonic Sciences, Barcelona Institute of Science and Technology, Max Planck Institute of Quantum Optics, Munich Center for Quantum Science and Technology, Ludwig-Maximilians-Universität München, Max Planck Institute for the Physics of Complex Systems, University at Buffalo, State University of New York
Language: English
Topic: Quantum many-body systems
Subfield: Atomic and Molecular Physics, and Optics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $3,450
Funders: National Science Foundation, Centres de Recerca de Catalunya, European Commission, Deutsche Forschungsgemeinschaft, Bundesministerium für Bildung und Forschung, Generalitat de Catalunya, QuantERA, Agència de Gestió d'Ajuts Universitaris i de Recerca, Agencia Estatal de Investigación, Kavli Institute for Theoretical Physics, University of California, Santa Barbara
Awards: G114984916, G1150230064, G1175115578, G1750626284, G1768993395, G1889978188, G1908469581, G2064873908, G210041235, G2152757567, FOR 5522: Quantenthermalisierung, Lokalisierung und eingeschränkte Dynamik mit wechselwirkenden ultrakalten Atomen, G2262748287, G2355262757, G2601397997, G2744928646, G2756433129, G2763573136, G288263039, G3005324705, G300979063, G3088423649, G3398237449, G34346518, G3480869486, G3681454997, G4042783231, G425668148, G434337789, G4689434848, G4710139657, G5080475149, G5195188938, G575169067, G5852091828, QuantERA II ERA-NET Cofund in Quantum Technologies, G6482940084, EXC 2147: Komplexität und Topologie in Quantenmaterialien (CT.QMAT), G6552004136, G6624113701, G6656126374, G69051668, Kavli Institute for Theoretical Physics, G7084143925, G7513402879, Quantensimulation mit konstruierter Dissipation, G8180681537, G8637226926, EXC 2111: Munich Center for Quantum Science and Technology (MCQST), G8809713225
OpenAlex ID: W4414927355