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Universal van der Waals Force Between Heavy Polarons in Superfluids
Physical Review Letters ( IF 8.1 ) Pub Date : 2022-11-30 , DOI: 10.1103/physrevlett.129.233401
Keisuke Fujii 1 , Masaru Hongo 2, 3 , Tilman Enss 1
Affiliation  

We investigate the long-range behavior of the induced Casimir interaction between two spinless heavy impurities, or polarons, in superfluid cold atomic gases. With the help of effective field theory (EFT) of a Galilean invariant superfluid, we show that the induced impurity-impurity potential at long distance universally shows a relativistic van der Waals-like attraction (1/r7) resulting from the exchange of two superfluid phonons. We also clarify finite temperature effects from the same two-phonon exchange process. The temperature T introduces the additional length scale cs/T with the speed of sound cs. Leading corrections at finite temperature scale as T6/r for distances rcs/T smaller than the thermal length. For larger distances the potential shows a nonrelativistic van der Waals behavior (T/r6) instead of the relativistic one. Our EFT formulation applies not only to weakly coupled Bose or Fermi superfluids but also to those composed of strongly correlated unitary fermions with a weakly coupled impurity. The sound velocity controls the magnitude of the van der Waals potential, which we evaluate for the fermionic superfluid in the BCS-BEC crossover.

中文翻译:

超流体中重极化子之间的通用范德华力

我们研究了超流冷原子气体中两种无自旋重杂质或极化子之间诱导的卡西米尔相互作用的长程行为。借助伽利略不变超流体的有效场论 (EFT),我们表明在远距离诱导的杂质-杂质势普遍表现出相对论的类范德华引力 (1个/r7) 由两个超流体声子的交换产生。我们还阐明了相同双声子交换过程的有限温度效应。气温引入额外的长度比例C/以音速C. 有限温标下的领先修正为6个/r对于距离rC/小于热长度。对于更大的距离,势能表现出非相对论的范德瓦尔斯行为(/r6个) 而不是相对论的。我们的 EFT 公式不仅适用于弱耦合玻色或费米超流体,还适用于由强相关酉费米子和弱耦合杂质组成的超流体。声速控制范德瓦尔斯势的大小,我们在 BCS-BEC 交叉中评估费米子超流体。
更新日期:2022-11-30
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