Speaker: Romain Vasseur (University of Massachusetts Amherst)

Time: 20:00-21:00 p.m., May 17, 2023, GMT+8

Venue: Zoom Meeting ID: 963 5796 8034 Password: 125125 or koushare platform (https://www.koushare.com/lives/room/715288)

Abstract:

Monitored random quantum circuits (MRCs) exhibit a measurement-induced phase transition between area-law andvolume-law entanglement scaling. In this talk,I will review the physics of such entanglement transitions, and argue that MRCs with a conserved charge additionally exhibit two distinct volumelaw entangled phases that cannot be characterized byequilibrium notions of symmetry-breaking or topological order, but rather by the non-equilibrium dynamics and steady-statedistribution of charge fluctuations. These include a charge-fuzzyphase in which charge information is rapidly scrambled leadinoto slowly decaying spatial fluctuations of charge in the steadystate, and a charge-sharp phase in which measurements collapse quantum fluctuations of charge without destroying thevolume-law entanglement of neutral degrees of freedom. I will present some statistical mechanics description of such charge-sharpening transitions, and relate them to the efficiency of classical decoders to“learn”the global charge of quantum systems from local measurements.

Source: School of Physics