Gullans Michael J, Huse David A
Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
Institute for Advanced Study, Princeton, New Jersey 08540, USA.
Phys Rev Lett. 2020 Aug 14;125(7):070606. doi: 10.1103/PhysRevLett.125.070606.
We uncover a local order parameter for measurement-induced phase transitions: the average entropy of a single reference qubit initially entangled with the system. Using this order parameter, we identify scalable probes of measurement-induced criticality that are immediately applicable to advanced quantum computing platforms. We test our proposal on a 1+1 dimensional stabilizer circuit model that can be classically simulated in polynomial time. We introduce the concept of a "decoding light cone" to establish the local and efficiently measurable nature of this probe. We also estimate bulk and surface critical exponents for the transition. Developing scalable probes of measurement-induced criticality in more general models may be a useful application of noisy intermediate scale quantum devices, as well as point to more efficient realizations of fault-tolerant quantum computation.
最初与系统纠缠的单个参考量子比特的平均熵。利用这个序参量，我们确定了可扩展的测量诱导临界性探测器，这些探测器可立即应用于先进的量子计算平台。我们在一个可以在多项式时间内进行经典模拟的1+1维稳定器电路模型上测试了我们的提议。我们引入了“解码光锥”的概念，以确立该探测器的局部且可有效测量的性质。我们还估计了该相变的体临界指数和表面临界指数。在更一般的模型中开发可扩展的测量诱导临界性探测器，可能是噪声中等规模量子器件的一个有用应用，同时也指向容错量子计算的更高效实现。
