Quantum Simulation of an FFLO Superconductor

超导电性的发现是20世纪物理学的一个分水岭时刻，引发了凝聚态物理的新领域，并使新技术成为可能。超导性的本质是，当某些材料冷却到临界温度T_c以下时，它会成为理想的电导体。温度通常低于空气液化的温度。超导性背后的机制并不完全清楚，我们也不知道T_c的上限。我们知道，带电粒子是一对电子，它们通过各种有效的相互作用相互弱束缚。提出的配对机制之一是“FFLO超导体”，以四个提出者的首字母命名，其中的配对可以在强磁场存在下幸存下来。尽管进行了多次搜索，但FFLO超导体仍然难以捉摸。然而，它的存在将使物理学家对超导的内部工作原理有更多的了解，并将开启新的应用，如超高速电子计算机和磁共振成像(MRI)。PI将使用量子模拟来实现FFLO超导体的模型，在该模型中，超冷原子代替电子，电子在由驻波组成的周期性晶格中运动。这种类型的量子模拟忠实地实现了FFLO超导体的模型，并将使PI和学生能够验证理论预测。几名学生有望在PI的这个项目中获得博士学位，其中一些人可能会在创新的初创公司找到工作，贡献他们的专业知识来开发量子计算的新技术。超导和磁性是电子材料中常见的物质相，但它们并不共存。如果库珀对获得有限的质心动量，而不是像标准超导理论中那样形成零动量对，那么FFLO超导体可以适应共存的磁场。人们认为，无论是在准一维还是在二维，FFLO在低维都是最受欢迎的。到目前为止，还没有关于有限动量库珀对的直接证据。PI将通过模拟受磁场作用的实际电子材料，通过将自旋不平衡的费米原子气体限制在使用2D光学晶格形成的一维波导的二维阵列中，来确定具有有限动量对的FFLO态是否为物质的合法相。晶格势足够弱，以至于相邻波导中的原子通过隧道耦合相互作用。由此产生的域名墙，即FFLO州的最终签名，将直接被想象出来。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

The discovery of superconductivity was a watershed moment in 20th century physics, sparking the new field of condensed matter physics, as well as enabling new technologies. The essence of superconductivity is that some materials become perfect conductors of electricity when cooled below a critical temperature Tc. Tc is typically below the temperature where air liquifies. The mechanisms that underlie superconductivity are not fully known, nor do we know the upper limit of Tc. We do know that the charge-carrying particles are pairs of electrons that are weakly bound to each other by various effective interactions. One of the proposed pairing mechanisms is the “FFLO superconductor,” named after the initials of the four proposers, in which the pairs may survive the presence of a strong magnetic field. Despite many searches, the FFLO superconductor remains elusive. Its existence, however, would give physicists more insight into the inner workings of superconductivity and it would unlock new applications, such as ultra-fast electronic computers and magnetic resonance imaging (MRI). The PI will use quantum simulation to realize a model of the FFLO superconductor, for which ultra-cold atoms stand-in for the electrons, which move in a periodic crystal lattice made from standing waves of light. This type of quantum simulation faithfully realizes a model of the FFLO superconductor and will enable the PI and students to test the theoretical predictions. Several students are expected to earn PhD degrees working on this project with the PI, and likely some of these will gain employment at innovative start-up companies contributing their expertise to develop new technologies for quantum computation.Superconductivity and magnetism are phases of matter commonly found in electronic materials that do not coexist. The FFLO superconductor may adapt to a co-existing magnetic field if the Cooper pairs acquire a finite center-of-mass momentum rather than forming zero momentum pairs as in the standard theory of superconductivity. It is believed that FFLO is most favored in low-dimensions, either in quasi-1D or 2D. As of yet, there is no direct evidence for finite momentum Cooper pairs. The PI will resolve whether the FFLO state, with finite-momentum pairing, is a legitimate phase of matter by simulating the actual electronic materials subjected to a magnetic field, with a spin-imbalanced atomic Fermi gas confined to a two-dimensional array of one-dimensional waveguides formed using a 2D optical lattice. The lattice potential is weak enough that atoms in adjacent waveguides interact via tunnel coupling. The resulting domain walls, the definitive signature of the FFLO state, will be directly imaged.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.