AG视讯厅

AG视讯厅:CMP Seminars

Randomness and Chaos in Qubit Models

Chen-Te Ma, the South China Normal University and the University of Cape Town
Mon, 2019-10-14 13:30 - 14:30
Room742 , New Science Building NO.5

We introduce randomness into a class of integrable models and study the spectral form factor as a diagnostic to distinguish between randomness and chaos. Spectral form factors exhibit a characteristic dip-ramp-plateau behavior in the $N>2$ SYK$_2$ model at high temperatures that is absent in the $N=2$ SYK$_2$ model. Our results suggest that this dip-ramp-plateau behavior implies the existence of random eigenvectors in a quantum many-body system. To further support this observation,  we examine the Gaussian random transverse Ising model and obtain consistent results without suffering from small $N$ issues. Finally, we demonstrate numerically that expectation values of observables computed in a random quantum state at late times are equivalent to the expectation values computed in the thermal ensemble in a Gaussian random one-qubit model.

Chen-Te Ma graduated from National Taiwan University in 2018. Currently, he is a postdoctoral research fellow in South China Normal University and the University of Cape Town. We has published 24 papers with 159 citations.

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