Zhang Leifeng, Che Yanming, Wang Jibiao, Chen Qijin
Department of Physics and Zhejiang Institute of Modern Physics, Zhejiang University, Hangzhou, Zhejiang, 310027, China.
Synergetic Innovation Center of Quantum Information and Quantum Physics, Hefei, Anhui, 230026, China.
Sci Rep. 2017 Oct 11;7(1):12948. doi: 10.1038/s41598-017-13321-3.
Atomic Fermi gases have been an ideal platform for simulating conventional and engineering exotic physical systems owing to their multiple tunable control parameters. Here we investigate the effects of mixed dimensionality on the superfluid and pairing phenomena of a two-component ultracold atomic Fermi gas with a short-range pairing interaction, while one component is confined on a one-dimensional (1D) optical lattice whereas the other is in a homogeneous 3D continuum. We study the phase diagram and the pseudogap phenomena throughout the entire BCS-BEC crossover, using a pairing fluctuation theory. We find that the effective dimensionality of the non-interacting lattice component can evolve from quasi-3D to quasi-1D, leading to strong Fermi surface mismatch. Upon pairing, the system becomes effectively quasi-two dimensional in the BEC regime. The behavior of T bears similarity to that of a regular 3D population imbalanced Fermi gas, but with a more drastic departure from the regular 3D balanced case, featuring both intermediate temperature superfluidity and possible pair density wave ground state. Unlike a simple 1D optical lattice case, T in the mixed dimensions has a constant BEC asymptote.
由于其具有多个可调节的控制参数，原子费米气体一直是模拟传统和工程奇异物理系统的理想平台。在此，我们研究混合维度对具有短程配对相互作用的双组分超冷原子费米气体的超流和配对现象的影响，其中一组分被限制在一维（1D）光学晶格上，而另一组分处于均匀的三维连续介质中。我们使用配对涨落理论研究了整个BCS - BEC交叉区域的相图和赝能隙现象。我们发现，非相互作用晶格组分的有效维度可以从准三维演变为准一维，导致强烈的费米面失配。配对后，系统在BEC区域有效地变为准二维。Tc的行为与常规三维粒子数不平衡费米气体的行为相似，但与常规三维平衡情况有更显著的偏离，具有中间温度超流性和可能的配对密度波基态。与简单的一维光学晶格情况不同，混合维度中的Tc具有恒定的BEC渐近线。
