Measurement-and Feedback-Driven Non-Equilibrium Phase Transitions on a Quantum Processor

Fuente: arXiv
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Main Authors: Wu, Zhiyi, Sun, Xuandong, Wang, Songlei, Zhang, Jiawei, Yang, Xiaohan, Chu, Ji, Niu, Jingjing, Zhong, Youpeng, Chen, Xiao, Yang, Zhi-Cheng, Yu, Dapeng
Format: Preprint
Published: 2025
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author Wu, Zhiyi
Sun, Xuandong
Wang, Songlei
Zhang, Jiawei
Yang, Xiaohan
Chu, Ji
Niu, Jingjing
Zhong, Youpeng
Chen, Xiao
Yang, Zhi-Cheng
Yu, Dapeng
author_facet Wu, Zhiyi
Sun, Xuandong
Wang, Songlei
Zhang, Jiawei
Yang, Xiaohan
Chu, Ji
Niu, Jingjing
Zhong, Youpeng
Chen, Xiao
Yang, Zhi-Cheng
Yu, Dapeng
contents Mid-circuit measurements and feedback operations conditioned on the measurement outcomes are essential for implementing quantum error-correction on quantum hardware. When integrated in quantum many-body dynamics, they can give rise to novel non-equilibrium phase transitions both at the level of each individual quantum trajectory and the averaged quantum channel. Experimentally resolving both transitions on realistic devices has been challenging due to limitations on the fidelity and the significant latency for performing mid-circuit measurements and feedback operations in real time. Here, we develop a superconducting quantum processor that enables global mid-circuit measurement with an average quantum non-demolition (QND) fidelity of 98.7% and fast conditional feedback with a 200 ns real-time decision latency. Using this platform, we demonstrate the coexistence of an absorbing-state transition in the quantum channel and a measurement-induced entanglement transition at the level of individual quantum trajectories. For the absorbing-state transition, we experimentally extract a set of critical exponents at the transition point, which is in excellent agreement with the directed percolation universality class. Crucially, the two transitions occur at distinct values of the tuning parameter. Our results demonstrate that adaptive quantum circuits provide a powerful platform for exploring non-equilibrium quantum many-body dynamics.
format Preprint
id arxiv_https___arxiv_org_abs_2512_07966
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Measurement-and Feedback-Driven Non-Equilibrium Phase Transitions on a Quantum Processor
Wu, Zhiyi
Sun, Xuandong
Wang, Songlei
Zhang, Jiawei
Yang, Xiaohan
Chu, Ji
Niu, Jingjing
Zhong, Youpeng
Chen, Xiao
Yang, Zhi-Cheng
Yu, Dapeng
Quantum Physics
Statistical Mechanics
Mid-circuit measurements and feedback operations conditioned on the measurement outcomes are essential for implementing quantum error-correction on quantum hardware. When integrated in quantum many-body dynamics, they can give rise to novel non-equilibrium phase transitions both at the level of each individual quantum trajectory and the averaged quantum channel. Experimentally resolving both transitions on realistic devices has been challenging due to limitations on the fidelity and the significant latency for performing mid-circuit measurements and feedback operations in real time. Here, we develop a superconducting quantum processor that enables global mid-circuit measurement with an average quantum non-demolition (QND) fidelity of 98.7% and fast conditional feedback with a 200 ns real-time decision latency. Using this platform, we demonstrate the coexistence of an absorbing-state transition in the quantum channel and a measurement-induced entanglement transition at the level of individual quantum trajectories. For the absorbing-state transition, we experimentally extract a set of critical exponents at the transition point, which is in excellent agreement with the directed percolation universality class. Crucially, the two transitions occur at distinct values of the tuning parameter. Our results demonstrate that adaptive quantum circuits provide a powerful platform for exploring non-equilibrium quantum many-body dynamics.
title Measurement-and Feedback-Driven Non-Equilibrium Phase Transitions on a Quantum Processor
topic Quantum Physics
Statistical Mechanics
url https://arxiv.org/abs/2512.07966