Dissipation-enhanced scrambling in the SYK model coupled to a lossy cavity

Abstract

We study the Yukawa-Sachdev-Ye-Kitaev model, a disordered model of $N$ Majorana fermions and $R=\gamma N$ bosons in which the bosons are linearly coupled to independent realizations of SYK $p$-body interactions, in the presence of dissipation, modeled by a Lindblad master equation. Motivated by recent proposals for implementing SYK models in quantum simulators, we focus on bosonic leakage at rate $\kappa$. Initializing the system in the steady state, we analyze the late-time fermionic relaxation rate and the Lyapunov exponent, solving the large-$N$ theory both numerically and for $p$ large, finding a rich landscape of dynamical behaviors. Most notably, the Lyapunov exponent remains positive for every value of $\kappa$ and, for $p>2$, can even grow as $\kappa$ increases. The QED case $p=2$, which lies between the fully chaotic regime $p>2$ and the integrable case $p=1$, exhibits special features. We also identify a critical value of the boson-to-fermion ratio $\gamma_c \approx 2/p^2$ separating distinct dynamical regimes.