真空拉比振荡中通过几何聚焦实现自旋压缩

中文摘要 AI 辅助

我们证明，真空拉比振荡可通过布洛赫球上的几何聚焦直接产生自旋压缩。初始处于真空态的腔与相干自旋态共振耦合，当集体自旋趋近原子基态时，布洛赫球的曲率会聚焦量子涨落，从而在运动方向的垂直方向产生压缩。压缩的时间尺度由集体拉比频率决定，即$t_s\sim 1/(g\sqrt{N})$。最优温兰（Wineland）压缩参数满足$\xi_{\rm opt}^2\propto N^{-1/3}$，这是几何聚焦效应与腔场真空涨落竞争的结果。该压缩对实际耗散具有鲁棒性。最后简要讨论了$^{171}$Yb的应用实例，以证明我们方案的可行性。

英文摘要

We show that vacuum Rabi oscillations can directly generate spin squeezing through geometric focusing on the Bloch sphere. Starting from a coherent spin state resonantly coupled to a cavity initially in the vacuum state, quantum fluctuations are focused by the curvature of the Bloch sphere as the collective spin approaches the atomic ground state, producing squeezing transverse to the direction of motion. The squeezing timescale is set by the collective Rabi frequency $t_s\sim 1/(g\sqrt{N})$. The optimal Wineland squeezing parameter scales as $ξ_{\rm opt}^2\propto N^{-1/3}$, which is an outcome of the competition between the geometric focusing effects and the cavity-field vacuum fluctuations. The squeezing remains robust against realistic dissipation. In the end, an application example of $^{171}$Yb is briefly discussed to show the feasibility of our protocol.

发表机构

• International Center for Quantum Materials, School of Physics, Peking University（北京大学物理学院量子材料中心）
• Beijing Key Laboratory of Quantum Devices, Peking University（北京大学量子器件北京市重点实验室）
• National Laboratory of Solid State Microstructures and School of Physics, Collaborative Innovation Center of Advanced Microstructures, Nanjing University（南京大学固体微结构物理国家重点实验室、物理学院、现代工程与应用科学协同创新中心）
• MIT-Harvard Center for Ultracold Atoms and Research Laboratory of Electronics, Massachusetts Institute of Technology（麻省理工学院电子研究实验室与MIT-哈佛超冷原子中心）

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