Entanglement transition from variable-strength weak measurements

Szyniszewski, Marcin; Romito, Alessandro; Schomerus, Henning

doi:10.1103/physrevb.100.064204

Cited by 229 publications

(154 citation statements)

References 52 publications

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“…1(b). In the case of P t = 1, P x is equivalent to the measurement rate considered in previous works [35][36][37][38]40]. In this case, the region of volume law phase in our model is very narrow.…”

Section: Resultsmentioning

confidence: 95%

“…However, this is not the case in generic interacting systems, where more subtle entanglement structures could survive under measurements. A stable volume law phase was found in several numerics [35][36][37][38][39][40]. By simulating hundreds qubits in Clifford circuits, it is found a continuous quantum dynamical phase transition from volume law to area law entanglement by continuously tuning the measurement rate [36,37].…”

Section: Introductionmentioning

confidence: 99%

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Measurement-induced phase transition: A case study in the nonintegrable model by density-matrix renormalization group calculations

Tang

Zhu

2020

Phys. Rev. Research

164

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We study the effects of local projective measurements on the quantum quench dynamics. As a concrete example, one-dimensional Bose-Hubbard model is simulated by using matrix product state and time evolving block decimation. We map out a global phase diagram in terms of the measurement rate in spatial space and time domain, which demonstrates a volume-to-area law entanglement phase transition. When the measurement rates reach the critical values, we observe a logarithmic growth of entanglement entropy as the sub-system size or evolved time increases. This is akin to the character in the many-body localization, implying a general picture of the dynamical transitions separating quantum systems with different entanglement features. Moreover, we find that the probability distribution of the single-site entanglement entropy distinguishes the volume and area law phases just as the case of disorder-induced many-body localization. This suggests that the different type entanglement phase transitions may be understood as a nonlocalized-to-localized transition. We also investigate the scaling behavior of entanglement entropy and mutual information between two separated intervals, which is indicative of a single universality class and thus suggests a possible unified description of this transition.

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Section: Resultsmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

Measurement-induced phase transition: A case study in the nonintegrable model by density-matrix renormalization group calculations

Tang

Zhu

2020

Phys. Rev. Research

164

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“…Tracking quantum trajectories has been exploited as a tool to engineering quantum states via continuous feedback control [8][9][10] and entanglement distillation [11,12]. It has been used to observe fundamental properties of quantum measurements [13][14][15][16][17] and, recently, to predict topological transitions in measurement-induced geometric phases [18][19][20][21] and many-body entanglement phase transitions in random unitary circuits, invisible to the average dynamics [22][23][24][25].…”

Section: Introductionmentioning

confidence: 99%

Quantum Zeno effect appears in stages

Snizhko

Kumar

Romito

2020

Phys. Rev. Research

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In the quantum Zeno effect, quantum measurements can block the coherent oscillation of a two level system by freezing its state to one of the measurement eigenstates. The effect is conventionally controlled by the measurement frequency. Here we study the development of the Zeno regime as a function of the measurement strength for a continuous partial measurement. We show that the onset of the Zeno regime is marked by a cascade of transitions in the system dynamics as the measurement strength is increased. Some of these transitions are only apparent in the collective behavior of individual quantum trajectories and are invisible to the average dynamics. They include the appearance of a region of dynamically inaccessible states and of singularities in the steady-state probability distribution of states. These predicted dynamical features, which can be readily observed in current experiments, show the coexistence of fundamentally unpredictable quantum jumps with those continuously monitored and reverted in recent experiments.

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“…The effective spin model may also be extended to dynamics with measurement, or other types of interaction with an environment, for example, to clarify the relationship between different universality classes of measurementinduced criticality [88,89,[93][94][95][96][97][98][99][100][101][102][103].…”

Section: Discussionmentioning

confidence: 99%

“…(47), we draw the dual-unitary tensor as a (fourfold symmetric) square in Eq. (97). For N ¼ 2, unitarity and dual unitarity can be used to propagate þþ (or −−) states from the top to bottom, right to left, and vice versa.…”

Section: ð97þmentioning

confidence: 99%

Entanglement Membrane in Chaotic Many-Body Systems

2020

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In certain analytically tractable quantum chaotic systems, the calculation of out-of-time-order correlation functions, entanglement entropies after a quench, and other related dynamical observables reduces to an effective theory of an "entanglement membrane" in spacetime. These tractable systems involve an average over random local unitaries defining the dynamical evolution. We show here how to make sense of this membrane in more realistic models, which do not involve an average over random unitaries. Our approach relies on introducing effective pairing degrees of freedom in spacetime, describing a pairing of forward and backward Feynman trajectories, inspired by the structure emerging in random unitary circuits. This viewpoint provides a framework for applying ideas of coarse graining to dynamical quantities in chaotic systems. We apply the approach to some translationally invariant Floquet spin chains studied in the literature. We show that a consistent line tension may be defined for the entanglement membrane and that there are qualitative differences in this tension between generic models and "dualunitary" circuits. These results allow scaling pictures for out-of-time-order correlators and for entanglement to be taken over from random circuits to nonrandom Floquet models. We also provide an efficient numerical algorithm for determining the entanglement line tension in 1 þ 1D.

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Entanglement transition from variable-strength weak measurements

Cited by 229 publications

References 52 publications

Measurement-induced phase transition: A case study in the nonintegrable model by density-matrix renormalization group calculations

Measurement-induced phase transition: A case study in the nonintegrable model by density-matrix renormalization group calculations

Quantum Zeno effect appears in stages

Entanglement Membrane in Chaotic Many-Body Systems

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