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Measurement-induced criticality in extended and long-range unitary circuits

by Shraddha Sharma, Xhek Turkeshi, Rosario Fazio, Marcello Dalmonte

Submission summary

As Contributors: Marcello Dalmonte · Shraddha Sharma
Arxiv Link: (pdf)
Date submitted: 2021-11-10 05:42
Submitted by: Sharma, Shraddha
Submitted to: SciPost Physics Core
Academic field: Physics
  • Condensed Matter Physics - Theory
  • Quantum Physics
Approach: Theoretical


We explore the dynamical phases of unitary Clifford circuits with variable-range interactions, coupled to a monitoring environment. We investigate two classes of models, distinguished by the action of the unitary gates, which either are organized in clusters of finite-range two-body gates, or are pair-wise interactions randomly distributed throughout the system with a power-law distribution. We find the range of the interactions plays a key role in characterizing both phases and their measurement-induced transitions. For the cluster unitary gates we find a transition between a phase with volume-law scaling of the entanglement entropy and a phase with area-law entanglement entropy. Our results indicate that the universality class of the phase transition is compatible to that of short range hybrid Clifford circuits. Oppositely, in the case of power-law distributed gates, we find the universality class of the phase transition changes continuously with the parameter controlling the range of interactions. In particular, for intermediate values of the control parameter, we find a non-conformal critical line which separates a phase with volume-law scaling of the entanglement entropy from one with sub-extensive scaling. Within this region, we find the entanglement entropy and the logarithmic negativity present a cross-over from a phase with algebraic growth of entanglement with system size, and an area-law phase.

Current status:
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Submission & Refereeing History

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Submission 2110.14403v2 on 10 November 2021

Reports on this Submission

Anonymous Report 1 on 2021-11-30 (Invited Report)


1) relevant
2) thoroughly investigated
3) clearly communicated


The paper investigates random circuits, where the applied quantum gates are randomly drawn from the Clifford group and where Pauli measurements are randomly performed in between consecutive gates . This permits a classical investigation of the dynamics of the models. Phase transitions in the dynamical evolution are explored as the range of interactions (implemented by the chosen gates) is varied. The paper predicts a range of interesting observations as the behavior of the critical exponents is studied. While not unexpected, a quantitative investigation of the findings is a highly relevant contribution to the very active field of dynamics in random circuits. Moreover the investigations are likely to become relevant for possible future experiments provided sufficient qubit numbers are reached.

  • validity: top
  • significance: high
  • originality: good
  • clarity: top
  • formatting: perfect
  • grammar: excellent

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