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Résumé |
Quantum systems evolving unitarily and subject to quantum measurements exhibit various types of non-
equilibrium phase transitions, arising from the competition between unitary evolution and measurements.
Dissipative phase transitions in steady states of time-independent Liouvillians and measurement induced
phase transitions at the level of quantum trajectories are two primary examples of such transitions.
Investigating a many-body spin system subject to periodic resetting measurements, we argue that many-
body dissipative Floquet dynamics provides a natural framework to analyze both types of transitions. We
show that a dissipative phase transition between a ferromagnetic ordered phase and a paramagnetic
disordered phase emerges for long-range systems as a function of measurement probabilities. A
measurement induced transition of the entanglement entropy between volume law scaling and sub-volume
law scaling is also present, and is distinct from the ordering transition. The two phases correspond to an
error-correcting and a quantum-Zeno regimes, respectively. The ferromagnetic phase is lost for short range
interactions, while the volume law phase of the entanglement is enhanced. |
