IQIM Virtual Seminar, October 16, 2020 - Yingfei Gu

Speaker: It from Qubit Postdoctoral Scholar, Kitaev Group
Title: Scrambling and Branching
Abstract: Out-of-time-order correlators (OTOCs) describe quantum chaos in a way comparable to classical chaos, at least for systems with a large parameter N, where the early-time OTOCs are characterized by a Lyapunov exponent, whose inverse defines a time scale known as Lyapunov time. In this talk, I will discuss another time scale called branching time and derive a bound on it for SYK-like models. It turns out that the branching time plays significantly different roles in the strong and weak coupling limits, suggesting two different mechanisms for scrambling. This talk is based on [1812.00120] with Alexei Kitaev and work in progress with Alexei Kitaev and Pengfei Zhang.