Chaotic quantum systems with Lyapunov exponent $\lambda_L$ obey a remarkable upper bound $\lambda_L\leq 2\pi k_BT/\hbar$ at temperature $T$, implying a divergence of the bound in the classical limit $\hbar\rightarrow 0$. Following this trend, does a quantum system necessarily become ‘more chaotic' when quantum fluctuations are reduced? I will explore this question by computing $\lambda_L(\hbar ,T )$ in the quantum spherical p-spin glass model, where $\hbar$ can be continuously varied. I will show that the approach to the classical limit could be non-trivial, with non-monotonic dependence of $\lambda_L$ on $\hbar$ close to the dynamical glass transition temperature $T_d$. The results in the classical limit ( $\hbar\rightarrow 0$ ) naturally describe chaos in super-cooled liquid in structural glasses. I will also discuss chaos in the replica symmetry breaking spin glass phase. If time permits, I will briefly discuss many-body chaos across Kosterlitz-Thouless and Ising transitions in the classical limit of two-dimensional XXZ spin model.
Zoom link: https://zoom.us/j/91458471087?pwd=QURYWUtPeHloMWp5Vlc1clV0bzBwUT09
Meeting ID: 914 5847 1087