Harris Joseph, Yan Bin, Sinitsyn Nikolai A
Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
Department of Applied Mathematics and Theoretical Physics, University of Cambridge, Cambridge CB3 0WA, United Kingdom.
Phys Rev Lett. 2022 Jul 29;129(5):050602. doi: 10.1103/PhysRevLett.129.050602.
Information scrambling refers to the rapid spreading of initially localized information over an entire system, via the generation of global entanglement. This effect is usually detected by measuring a temporal decay of the out-of-time order correlators. However, in experiments, decays of these correlators suffer from fake positive signals from various sources, e.g., decoherence due to inevitable couplings to the environment, or errors that cause mismatches between the purported forward and backward evolutions. In this Letter, we provide a simple and robust approach to single out the effect of genuine scrambling. This allows us to benchmark the scrambling process by quantifying the degree of the scrambling from the noisy backgrounds. We also demonstrate our protocol with simulations on IBM cloud-based quantum computers.
信息扩散是指通过全局纠缠的产生，使最初局部化的信息在整个系统中迅速传播。这种效应通常通过测量时间反序关联函数的时间衰减来检测。然而，在实验中，这些关联函数的衰减会受到来自各种源的假阳性信号的影响，例如，由于与环境不可避免的耦合导致的退相干，或导致所谓的正向和反向演化之间不匹配的误差。在本信函中，我们提供了一种简单且稳健的方法来区分真正扩散的效应。这使我们能够通过从噪声背景中量化扩散程度来对扩散过程进行基准测试。我们还在基于IBM云的量子计算机上通过模拟演示了我们的协议。
