Research Highlights
Quantum chaos and anomalous relaxation in open quantum circuits
We addressed the critical problem of relaxation in generic dissipative many-body systems, studying the interplay of chaos and dissipation in a family of open quantum circuits—a crucial paradigm for quantum computation. We unveiled that chaos can be robust against dissipation, preserving signatures from closed systems that provide key insights from condensed matter to quantum gravity, but can also assist and anomalously enhance relaxation.
We introduced a minimally-structured many-body chaotic open time-periodic circuit with arbitrary on-site dissipation, the dissipative random phase model (DRPM), which is amenable to analytic treatment. We find that, for a long enough time, the system always relaxes with two distinctive regimes characterized by the presence or absence of gap closing. With an appropriate scaling of dissipation strength, signatures of chaos are robust to dissipative perturbations in the gap-closing regime. On the other hand, relaxation is "assisted" by quantum chaos in the regime where the gap remains nonzero. In that regime, we prove that if the thermodynamic limit is taken first the gap does not close even in the dissipationless limit. This is the first analytic proof of ``anomalous relaxation'', a phenomenon recently uncovered in several distinct many-body quantum systems (ranging from the dissipative SYK model to quantum spin liquids).
Our work represents an essential step towards establishing the universal properties of complex dissipative matter and paves the way towards an understanding of the dynamical content of spectral correlations in open quantum systems.
Robustness of quantum chaos and anomalous relaxation in open quantum circuits, Takato Yoshimura and Lucas Sá, Nature Communications 15, 9808 (2024).