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arXiv · 2410.09331

Minutes-scale Schr{\"o}dinger-cat state of spin-5/2 atoms

Y. A. Yang·W. -T. Luo·J. -L. Zhang·S. -Z. Wang·Chang-Ling Zou·T. Xia·Z. -T. Lu
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Abstract

Quantum metrology with nonclassical states offers a promising route to improved precision in physical measurements. The quantum effects of Schr{\"o}dinger-cat superpositions or entanglements allow measurement uncertainties to reach below the standard quantum limit. However, the challenge in keeping a long coherence time for such nonclassical states often prevents full exploitation of the quantum advantage in metrology. Here we demonstrate a long-lived Schr{\"o}dinger-cat state of optically trapped $^{173}$Yb (\textit{I}\ =\ 5/2) atoms. The cat state, a superposition of two oppositely-directed and furthest-apart spin states, is generated by a non-linear spin rotation. Protected in a decoherence-free subspace against inhomogeneous light shifts of an optical lattice, the cat state achieves a coherence time of $1.4(1)\times 10^3$ s. A magnetic field is measured with Ramsey interferometry, demonstrating a scheme of Heisenberg-limited metrology for atomic magnetometry, quantum information processing, and searching for new physics beyond the Standard Model.

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Y. A. Yang, W. -T. Luo, J. -L. Zhang, S. -Z. Wang, Chang-Ling Zou, T. Xia, Z. -T. Lu. 2024-10-12. Minutes-scale Schr{\"o}dinger-cat state of spin-5/2 atoms. https://doi.org/10.1038/s41566-024-01555-3

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