Solid-state spin coherence time approaching the physical limit.

Han, Shuo; Ye, Xiangyu; Zhou, Xu; Liu, Zhaoxin; Guo, Yuhang; Wang, Mengqi; Ji, Wentao; Wang, Ya et al. · Sci Adv · 2025

basic_science · Level V

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Abstract

Extending the coherence time of quantum systems to their physical limit is a long-standing pursuit and critical for developing quantum science and technology. By characterizing all the microscopic noise sources of the electronic spin [nitrogen-vacancy (NV) center] in diamonds using complete noise spectroscopy, we observe a previously unforeseen noise spectrum manifested as the empirical limit ([Formula: see text]) that has puzzled researchers for decades in various solid-state systems. By implementing a corresponding dynamical decoupling strategy, we are able to surpass the empirical limit and approach the upper physical limit <i>T</i><sub>2</sub> = 2<i>T</i><sub>1</sub> for NVs, from room temperature down to 220 kelvin. Our observations, including the independence across different spatial sites and its dependence on temperature in the same way as spin-lattice relaxation, suggest an emerging decoherence mechanism dominated by spin-lattice interaction. These results provide a unified and universal strategy for characterizing and controlling microscopic noises, thereby paving the way for achieving the physical limit in various solid-state systems.