Solution of a Minimal Model for Many-Body Quantum Chaos

We solve a minimal model for an ergodic phase in a spatially extended quantum many-body system. The model consists of a chain of sites with nearest-neighbor coupling under Floquet time evolution. Quantum states at each site span a q-dimensional Hilbert space, and time evolution for a pair of sites is generated by a q2×q2 random unitary matrix. The Floquet operator is specified by a quantum circuit of depth two, in which each site is coupled to...