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arXiv · 2507.22982

Dynamical freezing and enhanced magnetometry in an interacting spin ensemble

Ya-Nan Lu·Dong Yuan·Yixuan Ma·Yan-Qing Liu·Si Jiang·Xiang-Qian Meng·Yi-Jie Xu·Xiu-Ying Chang·Chong Zu·Hong-Zheng Zhao·Dong-Ling Deng·Lu-Ming Duan·Pan-Yu Hou
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Abstract

Understanding and controlling non-equilibrium dynamics in quantum many-body systems is a fundamental challenge in modern physics, with profound implications for advancing quantum technologies. Typically, periodically driven systems in the absence of conservation laws thermalize to a featureless "infinite-temperature" state, erasing all memory of their initial conditions. However, this paradigm can break down through mechanisms such as integrability, many-body localization, quantum many-body scars, and Hilbert space fragmentation. Here, we report the experimental observation of dynamical freezing, a distinct mechanism of thermalization breakdown in driven systems, and demonstrate its application in quantum sensing using an ensemble of approximately $10^4$ interacting nitrogen-vacancy spins in diamond. By precisely controlling the driving frequency and detuning, we observe emergent long-lived spin magnetization and coherent oscillatory micromotions, persisting over timescales exceeding the interaction-limited coherence time ($T_2$) by more than an order of magnitude. Leveraging these unconventional dynamics, we develop a dynamical-freezing-enhanced ac magnetometry that extends optimal sensing times far beyond $T_2$, outperforming conventional dynamical decoupling magnetometry with a 4.3 dB sensitivity enhancement. Our results not only provide clear experimental observation of dynamical freezing -- a peculiar mechanism defying thermalization through emergent conservation laws -- but also establish a robust control method generally applicable to diverse physical platforms, with broad implications in quantum metrology and beyond.

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Ya-Nan Lu, Dong Yuan, Yixuan Ma, Yan-Qing Liu, Si Jiang, Xiang-Qian Meng, Yi-Jie Xu, Xiu-Ying Chang, Chong Zu, Hong-Zheng Zhao, Dong-Ling Deng, Lu-Ming Duan, Pan-Yu Hou. 2025-07-30. Dynamical freezing and enhanced magnetometry in an interacting spin ensemble. https://arxiv.org/abs/2507.22982

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