近日，北京大学介观物理国家重点实验室的孙风潇及其研究团队取得一项新进展。经过不懈努力，他们利用腔内与腔外同步挤压光实现光力冷却。相关研究成果已于2024年12月18日在国际知名学术期刊《物理评论A》上发表。

该研究团队提出一种实验上可行的替代方法，用于在远未分辨边带条件下，借助腔内和腔外挤压效应，实现光力系统中机械振子的高效基态冷却。在该方案中，将一个简并光学参量放大器置于光学腔内，以产生腔内挤压效应；此外，光学腔还被腔外挤压光驱动，即产生腔外挤压效应。

腔内挤压和腔外挤压所产生的量子干涉效应，可以完全抑制非共振斯托克斯加热过程，同时大大增强反斯托克斯冷却过程。因此，这种联合挤压方案能够在远离分辨边带条件的区域，将机械振子冷却到其量子基态。

与其他传统的光力冷却方案相比，该联合挤压方案中的单光子冷却率可以大幅提高近三个数量级。同时，实现基态冷却所需的耦合强度也可以显著降低。这一方案有望用于冷却大质量和低频的机械振子，为宏观量子系统中非经典态的制备和操控提供了前提条件，并为量子操控打下了重要基础。

附：英文原文

Title: Optomechanical cooling with simultaneous intracavity and extracavity squeezed light

Author: S. S. Zheng^1,2, F. X. Sun^2,*, M. Asjad^3,4, G. W. Zhang¹, J. Huo¹, J. Li¹, J. Zhou¹, Z. Ma¹, and Q. Y. He^2,5,6,7

Issue&Volume: 2024-12-18

Abstract: We propose an alternative experimentally feasible approach to achieve high-efficiency ground-state cooling of a mechanical oscillator in an optomechanical system under the deeply unresolved sideband condition with the assistance of both intracavity and extracavity squeezing. In the scheme, a degenerate optical parametric amplifier is placed inside the optical cavity, generating the intracavity squeezing; in addition, the optical cavity is driven by the extracavity squeezed light, namely the extracavity squeezing. The quantum interference effect generated by intracavity squeezing and extracavity squeezing can completely suppress the nonresonant Stokes heating process while greatly enhancing the anti-Stokes cooling process. Therefore, the joint-squeezing scheme is capable of cooling the mechanical oscillators to their quantum ground state in a regime far away from the resolved sideband condition. Compared with other traditional optomechanical cooling schemes, the single-photon cooling rate in this joint-squeezing scheme can be tremendously enlarged by nearly three orders of magnitude. At the same time, the coupling strength required to achieve ground-state cooling can be significantly reduced. This scheme is promising for cooling large-mass and low-frequency mechanical oscillators, which provides a prerequisite for preparing and manipulating nonclassical states in macroscopic quantum systems and lays a significant foundation for quantum manipulation.

DOI: 10.1103/PhysRevA.110.063520

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.063520