Emergent Phenomena Seminar 290S/QM Seminar Speaker Chunxiao Liu (UC Berkeley) Wednesday, September 22 at 2:00pm

Time/Venue Wednesday, September 22 at 2 pm in 402 Physics South and Zoom: https://berkeley.zoom.us/j/99523499113pwd=REovb3pyam03WXQwbEhrU3dqNHZvdz09 Meeting ID: 995 2349 9113 Passcode: 600704
Host Joel Moore
 The monitored Sachdev-Ye-Kitaev model: measurement-induced phase transition and errors
Abstract I will talk about the monitored Brownian Sachdev-Ye-Kitaev (SYK) model without and with errors [arXiv:2104.08270 and arXiv:2106.09635]. Without errors, the model exhibits a measurement-induced phase transition that can be understood as a symmetry-breaking transition of an effective Z4 magnet in the replica space. The errors describe the loss of information about the measurement outcomes and, when present, can be mapped to an emergent magnetic field in the Z4 magnet. I will discuss two cases: when errors are applied during the non-unitary evolution, the symmetry is explicitly broken independent of the measurement rate, leading to a volume-law Renyi entropy. When errors are applied at the end of the evolution, the error-induced magnetic field only exists near the boundary of the magnet and can lead to a pinning transition of domain walls that corresponds to error threshold of the quantum code prepared by the non-unitary SYK dynamics.

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