Moghaddam Ali G, Pöyhönen Kim, Ojanen Teemu
Computational Physics Laboratory, Physics Unit, Faculty of Engineering and Natural Sciences, Tampere University, FI-33014 Tampere, Finland.
Helsinki Institute of Physics, University of Helsinki, Helsinki FI-00014, Finland.
Phys Rev Lett. 2023 Jul 14;131(2):020401. doi: 10.1103/PhysRevLett.131.020401.
Recently discovered measurement-induced entanglement phase transitions in monitored quantum circuits provide a novel example of far-from-equilibrium quantum criticality. Here, we propose a highly efficient strategy for experimentally accessing these transitions through fluctuations. Instead of directly measuring entanglement entropy, which requires an exponential number of measurements in the subsystem size, our method provides a scalable approach to entanglement transitions in the presence of conserved quantities. In analogy to entanglement entropy and mutual information, we illustrate how bipartite and multipartite fluctuations can both be employed to analyze the measurement-induced criticality. Remarkably, the phase transition can be revealed by measuring fluctuations of only a handful of qubits.
最近在受监测量子电路中发现的测量诱导纠缠相变提供了一个远离平衡量子临界性的新例子。在此，我们提出一种通过涨落来实验性地实现这些相变的高效策略。我们的方法并非直接测量纠缠熵（这在子系统规模中需要指数数量的测量），而是在存在守恒量的情况下，为纠缠相变提供了一种可扩展的方法。类似于纠缠熵和互信息，我们说明了如何利用二分涨落和多分涨落来分析测量诱导的临界性。值得注意的是，仅通过测量少数几个量子比特的涨落就能揭示相变。
