Time:  09:30 am (UTC/GMT+08:00, Beijing/Shanghai), Dec. 28 (Mon.), 2020

Online Meeting Room (zoom.us):  Click here to join the meeting

Meeting ID:  963 5084 9749

Speaker: Chao-Ming JIAN (Cornell Univ.)

Abstract:

For quantum systems at equilibrium, quantum criticality can often be understood following the principle of symmetry and topology. In contrast, quantum systems out of equilibrium can exhibit different dynamical phases and criticality that are fundamentally distinguishable only by their internal entanglement dynamics and scaling. Recently, entanglement phases and entanglement criticality in dynamical systems have attracted lots of attention. In particular, many entanglement critical points have been found and explored numerically. Due to the exotic nature of these numerically-observed entanglement phases, the analytical understandings of many of them remains elusive. In this talk, I will present two examples of entanglement quantum criticality that can be studied analytically. The first example concerns random unitary circuits with projective measurements where an exact mapping to a statistical mechanics model enables the analytical understanding of two different entanglement phases and the critical point between them. In the second example, I will discuss a critical entanglement phase in the system of random non-unitary circuits of non-interacting fermions and random Gaussian tensor network. I will show that this critical entanglement phase can be described by the theory of (unitary) disordered metal in the symmetry class DIII. Such an analytical understanding is based on a general correspondence among random non-unitary circuits of non-interacting fermions, random Gaussian tensor networks, and unitary systems of disordered fermions.

Invited by Prof. Long Zhang