Seetharam Kushal, Shchadilova Yulia, Grusdt Fabian, Zvonarev Mikhail B, Demler Eugene
Department of Electrical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA.
Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA.
Phys Rev Lett. 2021 Oct 29;127(18):185302. doi: 10.1103/PhysRevLett.127.185302.
The challenge of understanding the dynamics of a mobile impurity in an interacting quantum many-body medium comes from the necessity of including entanglement between the impurity and excited states of the environment in a wide range of energy scales. In this Letter, we investigate the motion of a finite mass impurity injected into a three-dimensional quantum Bose fluid as it starts shedding Bogoliubov excitations. We uncover a transition in the dynamics as the impurity's velocity crosses a critical value that depends on the strength of the interaction between the impurity and bosons as well as the impurity's recoil energy. We find that in injection experiments, the two regimes differ not only in the character of the impurity velocity abatement but also exhibit qualitative differences in the Loschmidt echo, density ripples excited in the Bose-Einstein condensate, and momentum distribution of scattered bosonic particles. The transition is a manifestation of a dynamical quantum Cherenkov effect and should be experimentally observable with ultracold atoms using Ramsey interferometry, rf spectroscopy, absorption imaging, and time-of-flight imaging.
理解相互作用量子多体介质中移动杂质动力学的挑战源于在广泛的能量尺度范围内，需要考虑杂质与环境激发态之间的纠缠。在本信函中，我们研究了注入三维量子玻色流体中的有限质量杂质开始散射玻戈留波夫激发时的运动。我们发现，当杂质速度超过一个临界值时，动力学发生转变，该临界值取决于杂质与玻色子之间的相互作用强度以及杂质的反冲能量。我们发现在注入实验中，这两种状态不仅在杂质速度衰减的特性上有所不同，而且在洛施密特回波、玻色 - 爱因斯坦凝聚体中激发的密度波动以及散射玻色子粒子的动量分布方面也表现出质的差异。这种转变是动态量子切伦科夫效应的一种表现，并且应该可以通过使用拉姆齐干涉测量法、射频光谱学、吸收成像和飞行时间成像的超冷原子实验进行观测。
