2024/10/12 by Yutong Yang, Yang, Y. A., Wei Luo +11 · 1 citation
Physics and Astronomy · #Cold Atom Physics and Bose-Einstein Condensates #Quantum optics and atomic interactions #Quantum and electron transport phenomena
paper · pdf · doi:10.48550/arxiv.2410.09331
Quantum metrology with nonclassical states offers a promising route to improved precision in physical measurements. The quantum effects of Schrödinger-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 Schrödinger-cat state of optically trapped 173Yb (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)× 103 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.