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

Host: Meng Cheng (m.cheng@yale.edu)

# Condensed Matter Theory Seminar: Romain Vasseur - “Learning Global Charges from Local Measurements”

Event time:

Thursday, May 18, 2023 - 1:00pm to 2:00pm

Location:

Sloane Physics Laboratory (SPL), Room 51

217 Prospect Street

New Haven, CT
06511
Event description:

Contact:

(see "Description" above)