Measurement-induced topological entanglement transitions in symmetric random quantum circuits
Measurement-induced topological entanglement transitions in symmetric random quantum circuits
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DOI：
10.1038/s41567-020-01112-z
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发表时间：
2021-01-04
期刊：
影响因子：
19.6
通讯作者：
Barkeshli, Maissam
中科院分区：
文献类型：
--
作者：
Lavasani, Ali;Alavirad, Yahya;Barkeshli, Maissam
在随机量子电路中，一组量子比特受到一系列随机选择的幺正操作，这为多体量子纠缠的动力学提供了关键的见解。最近的工作表明，将酉操作与单量子比特测量交错可以驱动高纠缠和低纠缠阶段之间的过渡。在这里，我们研究了一类对称随机量子电路，除了幺正动力学之外，还具有两种竞争类型的测量。我们发现一个丰富的相图，涉及强大的保序拓扑，平凡和体积法纠缠阶段，其中的过渡是隐藏的期望值的任何运营商，只有通过平均量子轨迹的纠缠熵是显而易见的。在没有幺正动力学的情况下，我们发现了一个纯粹的测量诱导的临界点，它正好映射到一个经典的二维渗流问题的两个副本。数值模拟表明，这种转变是一个三临界点，分裂成两个临界线在任意稀疏的幺正动力学与介入体积法纠缠相的存在。我们的研究结果表明，单独的测量是足以诱导临界和对数纠缠缩放，和任意稀疏幺正动力学可以足以稳定体积法纠缠阶段的存在下，快速，但竞争，测量。
Random quantum circuits, in which an array of qubits is subjected to a series of randomly chosen unitary operations, have provided key insights into the dynamics of many-body quantum entanglement. Recent work has shown that interleaving the unitary operations with single-qubit measurements can drive a transition between high- and low-entanglement phases. Here we study a class of symmetric random quantum circuits with two competing types of measurement in addition to unitary dynamics. We find a rich phase diagram involving robust symmetry-protected topological, trivial and volume law entangled phases, where the transitions are hidden to expectation values of any operator and are only apparent by averaging the entanglement entropy over quantum trajectories. In the absence of unitary dynamics, we find a purely measurement-induced critical point, which maps exactly to two copies of a classical two-dimensional percolation problem. Numerical simulations indicate that this transition is a tricritical point that splits into two critical lines in the presence of arbitrarily sparse unitary dynamics with an intervening volume law entangled phase. Our results show that measurements alone are sufficient to induce criticality and logarithmic entanglement scaling, and arbitrarily sparse unitary dynamics can be sufficient to stabilize volume law entangled phases in the presence of rapid, yet competing, measurements.