Arresting Quantum Chaos Dynamically in Transmon Arrays

Kavli Affiliate: Debanjan Chowdhury

| First 5 Authors: Rohit Mukherjee, Haoyu Guo, Keiran Lewellen, Debanjan Chowdhury,

| Summary:

Ergodic quantum many-body systems evolving under unitary time dynamics
typically lose memory of their initial state via information scrambling. Here
we consider a paradigmatic translationally invariant many-body Hamiltonian of
interacting bosons — a Josephson junction array in the transmon regime — in
the presence of a strong Floquet drive. Generically, such a time-dependent
drive is expected to heat the system to an effectively infinite temperature,
featureless state in the late-time limit. However, using numerical
exact-diagonalization we find evidence of special ratios of the drive amplitude
and frequency where the system develops {it emergent} conservation laws, and
{it approximate} integrability. Remarkably, at these same set of points, the
Lyapunov exponent associated with the semi-classical dynamics for the coupled
many-body equations of motion drops by orders of magnitude, arresting the
growth of chaos. We supplement our numerical results with an analytical
Floquet-Magnus expansion that includes higher-order corrections, and capture
the slow dynamics that controls decay away from exact freezing.

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