Abstract
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. An analysis of multifractal properties of wave function in Hilbert space provides a common perspective on both types of transitions in the system. Our findings are immediately relevant to trapped ion experiments, for which we detail a blueprint proposal based on currently available platforms.
Highlights
The interplay of coherent and incoherent dynamics has a rich and long history in the context of quantum physics
In this work we proposed a new framework to simultaneously investigate dissipative and measurementinduced phase transitions in experimentally realizable quantum-many body systems, whose dynamics is captured by a dissipative Floquet theory
We considered a kicked Ising model with resetting, and found that both a dissipative phase transitions (DPT) and a measurement induced” phase transition (MIPT) emerge as a result of the interplay between the unitary dynamics and the random quantum measurements
Summary
The interplay of coherent and incoherent dynamics has a rich and long history in the context of quantum physics. In parallel to these developments, a series of recent works has introduced a new perspective that, instead of focusing on the properties of the average steady state, studies the many-body properties at the level of single quantum trajectories In this context, it has been shown how the competition between quantum measurements and coherent dynamics (either analog or digitally generated) can give rise to transitions that manifest themselves in specific observables that are not properties of the averaged state - such as von Neumann entropies, negativities, or two-time correlation functions. While both types of transitions are clear footprints of the competition between coherent and incoherent dynamics, the interplay between them has so far received little attention, in part due to the fact that the two are typically formulated within rather different frameworks
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