A single impurity in an ideal atomic Fermi gas: current understanding and some open problems
A single impurity in an ideal atomic Fermi gas: current understanding and some open problems
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发表时间：
2014-04
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通讯作者：
Z. Lan;C. Lobo
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作者：
Z. Lan;C. Lobo
我们简要回顾了零温下三维极化费米原子气中单个无自旋杂质问题的一些现有的理论和实验方面，其中相互作用可以用宽的Feshbach共振来调谐。我们发现，在真空中，由杂质和背景气体原子(单杂质、二聚体、三聚体、四聚体)组成的各种少数体态在气体中产生相应的修饰态({em极化子}、{em二聚体}、{em三聚子}、{em四聚体})，并继承了它们的许多特性。我们研究了基态，重点研究了波函数的选择及其性质。我们提出了几个悬而未决的问题：极化子和二聚体是否真的是独立的分支，可能存在的其他少数体态，大量粒子-空穴对的基态的性质，以及为什么极化子ansatz如此之好。然后我们转向激发态，以及有效质量的计算。我们考察了有效质量的界限，并提出了关于复合准粒子态的一个猜想。
We briefly review some current theoretical and experimental aspects of the problem of a single spinless impurity in a 3D polarised atomic Fermi gas at zero temperature where the interactions can be tuned using a wide Feshbach resonance. We show that various few-body states in vacuum composed of the impurity and background gas atoms (single impurity, dimer, trimer, tetramer) give rise to corresponding dressed states ({\em polaron}, {\em dimeron}, {\em trimeron}, {\em tetrameron}) in the gas and inherit many of their characteristics. We study the ground state focussing on the choice of wave function and its properties. We raise a few unsolved problems: whether the polaron and dimeron are really separate branches, what other few-body states might exist, the nature of the groundstate for large numbers of particle-hole pairs and why is the polaron ansatz so good. We then turn to the excited states, and to the calculation of the effective mass. We examine the bounds on the effective mass and raise a conjecture about that of composite quasiparticle states.