Universality of stochastic control of quantum chaos with measurement and feedback

Abstract: We investigate quantum dynamics in the vicinity of an unstable fixed point subjected to stochastic control. The stochastic competition between the system's inherent instability (pushing trajectories away) and engineered control dynamics (drawing them back to the same point) forms the core of probabilistic control in chaotic systems. Recent studies reveal that this interplay underlies a family of measurement- and feedback-driven dynamical quantum phase transitions. To capture its universal features, we consider the inverted harmonic oscillator, a canonical model whose operator amplitudes diverge. Our control scheme, a quantum version of classical attractor dynamics, employs non-unitary evolution via measurements and conditional resets. By combining numerical simulations, a semiclassical Fokker-Planck analysis, and direct spectra of the quantum channel, we map out the control transition and uncover quantum-specific signatures of the underlying dynamics. We demonstrate the universality of our results within the quantum Arnold cat map, a paradigmatic model of quantum chaos.