Turlapov A V, Yu Kagan M
Institute of Applied Physics, Russian Academy of Sciences, ul. Ulyanova 46, 603000 Nizhniy Novgorod, Russia. N. I. Lobachevsky State University of Nizhni Novgorod, prosp. Gagarina 23, 603950 Nizhniy Novgorod, Russia.
J Phys Condens Matter. 2017 Sep 27;29(38):383004. doi: 10.1088/1361-648X/aa7ad9. Epub 2017 Jun 21.
The physics of many-body systems where particles are restricted to move in two spatial dimensions is challenging and even controversial: on one hand, neither long-range order nor Bose condensation may appear in infinite uniform 2D systems at finite temperature, on the other hand this does not prohibit superfluidity or superconductivity. Moreover, 2D superconductors, such as cuprates, are among the systems with the highest critical temperatures. Ultracold atoms are a platform for studying 2D physics. Unique from other physical systems, quantum statistics may be completely changed in an ultracold gas: an atomic Fermi gas may be smoothly crossed over into a gas of Bose molecules (or dimers) by tuning interatomic interactions. We review recent experiments where such crossover has been demonstrated, as well as critical phenomena in the Fermi-to-Bose crossover. We also present simple theoretical models describing the gas at different points of the crossover and compare the data to these and more advanced models.
在粒子被限制在二维空间中运动的多体系统物理学既具有挑战性，甚至还存在争议：一方面，在有限温度下的无限均匀二维系统中，既不会出现长程序，也不会出现玻色凝聚；另一方面，这并不排除超流性或超导性。此外，二维超导体，如铜酸盐，属于具有最高临界温度的系统。超冷原子是研究二维物理学的一个平台。与其他物理系统不同，量子统计在超冷气体中可能会完全改变：通过调节原子间相互作用，原子费米气体可以平滑地转变为玻色分子（或二聚体）气体。我们回顾了最近展示这种转变的实验，以及费米子到玻色子转变中的临界现象。我们还给出了描述转变不同点处气体的简单理论模型，并将数据与这些模型以及更先进的模型进行比较。
