Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria and Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck, Austria.
Phys Rev Lett. 2023 Mar 3;130(9):093601. doi: 10.1103/PhysRevLett.130.093601.
We propose and theoretically analyze an experiment where displacement sensing of an optically levitated nanoparticle in front of a surface can be used to measure the induced dipole-dipole interaction between the nanoparticle and its thermal image. This is achieved by using a surface that is transparent to the trapping light but reflective to infrared radiation, with a reflectivity that can be time modulated. This dipole-dipole interaction relies on the thermal radiation emitted by a silica nanoparticle having sufficient temporal coherence to correlate the reflected radiation with the thermal fluctuations of the dipole. The resulting force is orders of magnitude stronger than the thermal gradient force, and it strongly depends on the internal temperature of the nanoparticle for a particle-to-surface distance greater than two micrometers. We argue that it is experimentally feasible to use displacement sensing of a levitated nanoparticle in front of a surface as an internal thermometer in ultrahigh vacuum. Experimental access to the internal physics of a levitated nanoparticle in vacuum is crucial to understanding the limitations that decoherence poses to current efforts devoted to preparing a nanoparticle in a macroscopic quantum superposition state.
我们提出并从理论上分析了一个实验，其中可以用光悬浮纳米粒子在表面前的位移感测来测量纳米粒子与其热像之间的感应偶极-偶极相互作用。这是通过使用对捕获光透明但对红外辐射反射的表面来实现的，其反射率可以进行时间调制。这种偶极-偶极相互作用依赖于具有足够时间相干性的二氧化硅纳米粒子发出的热辐射，以便将反射辐射与偶极的热波动相关联。所产生的力比热梯度力强几个数量级，并且对于大于两个微米的粒子-表面距离，它强烈依赖于纳米粒子的内部温度。我们认为，在超高真空下，使用悬浮在表面前的纳米粒子的位移感测作为内部温度计在实验上是可行的。在真空下对悬浮纳米粒子的内部物理的实验访问对于理解退相干对当前致力于将纳米粒子制备在宏观量子叠加态的努力所带来的限制至关重要。
