近日，德国马克斯普朗克光学研究所的Pardeep Kumar等人合作并取得一项新进展。经过不懈努力，他们成功在标准量子极限之外感知原子超流体旋转。相关研究成果已于2024年11月18日在国际知名学术期刊《物理评论A》上发表。

在这项工作中，该研究团队构建了一个理论框架，该框架利用了凝聚体散射模式与光之间相互作用，可简化为有效光力运动方程的特性。研究人员进行了详细的理论分析，证明通过采用压缩光和反作用规避技术，可以实现对凝聚体角动量的测量，且测量噪声远低于标准量子极限。这一提案对原子电子学、量子传感和量子信息领域具有重要意义。

据悉，目前，在环形阱中利用玻色-爱因斯坦凝聚体（BECs）形成的原子超流体，正在超流体水动力学、量子传感和物质波干涉测量等领域进行研究。表征这类超流体的旋转特性至关重要，但目前只能通过光学吸收成像来实现，而这一过程会完全破坏凝聚体。

近期研究提出，将环形BEC与携带轨道角动量的光学腔模耦合，以实现对凝聚体旋转的最小破坏性测量。然而，这些提案的灵敏度受到由激光散粒噪声和辐射压力噪声共同作用，所设定的标准量子极限的限制。

附：英文原文

Title: Sensing atomic superfluid rotation beyond the standard quantum limit

Author: Rahul Gupta, Pardeep Kumar, Rina Kanamoto, M. Bhattacharya, Himadri Shekhar Dhar

Issue&Volume: 2024/11/18

Abstract: Atomic superfluids formed using Bose-Einstein condensates (BECs) in a ring trap are currently investigated in the context of superfluid hydrodynamics, quantum sensing, and matter-wave interferometry. The characterization of the rotational properties of such superfluids is important, but can presently only be performed by using optical absorption imaging, which completely destroys the condensate. Recent studies have proposed coupling the ring BEC to optical cavity modes carrying orbital angular momentum to make minimally destructive measurements of the condensate rotation. The sensitivity of these proposals, however, is bounded below by the standard quantum limit set by the combination of laser shot noise and radiation pressure noise. In this work we provide a theoretical framework that exploits the fact that the interaction between the scattered modes of the condensate and the light reduces to effective optomechanical equations of motion. We present a detailed theoretical analysis to demonstrate that the use of squeezed light and backaction evasion techniques allows the angular momentum of the condensate to be sensed with noise well below the standard quantum limit. Our proposal is relevant to atomtronics, quantum sensing, and quantum information.

DOI: 10.1103/PhysRevA.110.053514

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.053514