近日，美国麻省理工学院的Kushal Seetharam与哈佛大学的Yulia Shchadilova等人合作并取得一项新进展。他们揭示了有限动量玻色极化子的量子切伦科夫跃迁。相关研究成果已于2024年12月5日在国际知名学术期刊《物理评论A》上发表。

该团队研究了浸没在弱相互作用的三维超冷原子玻色-爱因斯坦凝聚体中的，有限动量杂质的行为，详细阐述了K. Seetharam等人在文献[Phys. Rev. Lett. 127, 185302 (2021)]中所讨论的动态量子切伦科夫跃迁。

采用时间依赖的变分方法，研究人员在开启吸引性短程杂质-玻色子相互作用后，发现了系统远离平衡态动力学中的一个转变。当杂质的速度超过一个与相互作用有关的临界值时，就会发生这种跃迁，并体现在洛施密特回波和杂质平均速度的长期行为中。

这种行为也反映在系统的有限动量基态上，即当跨越临界点时，相互作用修饰的杂质的群速度将不再依赖于系统的总动量。该研究所讨论的这一转变应可通过超冷原子系统中的，多种常用实验方案（如飞行时间成像、射频光谱学、拉姆齐干涉法和吸收成像）进行观测。

附：英文原文

Title: Quantum Cherenkov transition of finite-momentum Bose polarons

Author: Kushal Seetharam, Yulia Shchadilova, Fabian Grusdt, Mikhail Zvonarev, Eugene Demler

Issue&Volume: 2024/12/05

Abstract: We investigate the behavior of a finite-momentum impurity immersed in a weakly interacting three-dimensional Bose-Einstein condensate of ultracold atoms, giving a detailed account of the dynamical quantum Cherenkov transition discussed by K. Seetharam et al. [Phys. Rev. Lett. 127, 185302 (2021)]. Using a time-dependent variational approach, we identify a transition in the far-from-equilibrium dynamics of the system after the attractive short-range impurity-boson interaction is quenched on. The transition occurs as the impurity's velocity crosses an interaction-dependent critical value and manifests in the long-time behavior of the Loschmidt echo and average impurity velocity. This behavior is also reflected in the finite-momentum ground state of the system, where the group velocity of the interaction-dressed impurity loses its dependence on the total momentum of the system as the critical point is crossed. The transition we discuss should be experimentally observable via a variety of common protocols in ultracold atomic systems such as time-of-flight imaging, rf spectroscopy, Ramsey interferometry, and absorption imaging.

DOI: 10.1103/PhysRevA.110.063306

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.110.063306