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arXiv · 2607.14223

Quantum many-body mixed phase space revealed by hybrid feedback control

Hang Dong·Jie Ren·Andrew Hallam·Han Wang·Zhengyi Cui·Yiren Zou·Junlin Wang·Hekang Li·Qiujiang Guo·Zhen Wang·Lei Ying·Zlatko Papic
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Abstract

Understanding how complex systems transition between order and chaos is a central challenge of nonequilibrium physics. While weak perturbations of classical integrable systems give rise to a mixed phase space of coexisting regular and chaotic trajectories, analogous behavior in interacting quantum many-body systems has remained elusive. Here we develop and experimentally implement a hybrid quantum-classical feedback protocol that autonomously discovers and stabilizes long-lived regular trajectories in a superconducting quantum processor. Each iteration combines short-time quantum evolution with classical optimization that projects the dynamics back onto a low-entanglement variational manifold, effectively distilling coherence from chaotic evolution. The stabilized trajectories reveal a quantum many-body mixed phase space emerging from nonlinear variational dynamics, without a direct analogue in classical or few-body quantum systems. Our results establish a versatile framework for algorithmic discovery and control of coherent dynamics previously inaccessible to experiment.

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Hang Dong, Jie Ren, Andrew Hallam, Han Wang, Zhengyi Cui, Yiren Zou, Junlin Wang, Hekang Li, Qiujiang Guo, Zhen Wang, Lei Ying, Zlatko Papic. 2026-07-15. Quantum many-body mixed phase space revealed by hybrid feedback control. https://arxiv.org/abs/2607.14223

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