Solution of a minimal model for many-body quantum chaos
Andrea de Luca (Rudolf Peierls Centre for Theoretical Physics, Oxford University, UK)
I present a minimal model for quantum chaos in a spatially extended many-body system. It consists of a chain of sites with nearest-neighbour 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, in which each site is coupled to its neighbour on one side during the first half of the evolution period, and to its neighbour on the other side during the second half of the period. I will introduce a diagrammatic formalism useful to average the many-body dynamics over realisations of the random matrices. This approach leads to exact expressions in the large-q limit and sheds light on the universality of random matrices in many-body quantum systems and the ubiquitous entanglement growth in out-of-equilibrium dynamics.