Special QM/AMO Seminar Speaker Pedram Roushan (Google Inc.) Friday, February 14, 2 pm in LeConte 3

Time/Venue 2 pm in LeConte 3
Host Norman Yao
Title Entanglement dynamics in ergodic and many-body localized phase; A look under the hood of quantum supremacy
Abstract When various parts of a quantum system interact information is distributed between them. This process leads to growth of correlations and spread of entanglement. In physical platforms, proper measurement of spread of information and distilling it from noise is challenging. Here, we devise a protocol and measure scrambling in random quantum circuits, known to generate ergodic dynamics. We measure out-of-time-order correlations (OTOC) and visualize quantum scrambling in 1D and 2D arrays. We observe a diffusive propagation of wave front and are able to control it by changing the integrability of the hamiltonian of the system.
The many-body localized (MBL) phase has distinctive signatures such as slow dephasing and logarithmic entanglement growth that result in slow and subtle modification of the dynamics. By implementing phase sensitive techniques, we map out the structure of local integrals of motion in the MBL phase and determine the spatio-temporal entanglement growth between the localized sites. In addition, we study the preservation of entanglement in the MBL phase. The interferometric protocols implemented here measure affirmative correlations and exclude artifacts due to the imperfect isolation of the system.

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