Observing the Quantum Mpemba Effect in Quantum Simulations

The nonequilibrium physics of many-body quantum systems harbors various unconventional phenomena. In this Letter, we experimentally investigate one of the most puzzling of these phenomena—the quantum Mpemba effect, where a tilted ferromagnet restores its symmetry more rapidly when it is farther from the symmetric state compared to when it is closer. We present the first experimental evidence of the occurrence of this effect in a trapped-ion quantum simulator. The symmetry breaking and restoration are monitored through entanglement asymmetry, probed via randomized measurements, and postprocessed using the classical shadows technique. Our findings are further substantiated by measuring the Frobenius distance between the experimental state and the stationary thermal symmetric theoretical state, offering direct evidence of subsystem thermalization.Received 18 January 2024Accepted 29 March 2024DOI:https://doi.org/10.1103/PhysRevLett.133.010402© 2024 American Physical SocietyPhysics Subject Headings (PhySH)Research AreasOpen quantum systems & decoherenceQuantum controlQuantum measurementsQuantum quenchQuantum simulationQuantum statistical mechanicsQuantum thermodynamicsQuantum transportStatistical Physics & ThermodynamicsQuantum Information, Science & Technology