Department of Physics, Kyoto University, Oiwake-cho, Kitashirakawa, Sakyo-ku, Kyoto 606-8502, Japan.
Department of Physics, Yamagata University, Kojirakawa-machi 1-4-12, Yamagata, Yamagata 990-8560, Japan.
Phys Rev Lett. 2019 Aug 16;123(7):075303. doi: 10.1103/PhysRevLett.123.075303.
We study the Berezinskii-Kosterlitz-Thouless (BKT) transition of two-component Bose mixtures in two spatial dimensions. When phases of both components are decoupled, half-quantized vortex-antivortex pairs of each component induce two-step BKT transitions. On the other hand, when phases of both components are synchronized through the intercomponent Josephson coupling, two species of vortices of each component are bound to form a molecule, and, in this case, we find that there is only one BKT transition by molecule-antimolecule pairs. Our results can be tested by two weakly connected Bose systems such as two-component ultracold diluted Bose mixtures with the Rabi oscillation, and multiband superconductors.
我们研究了二维双分量玻色混合物中的 Berezinskii-Kosterlitz-Thouless（BKT）相变。当两个分量的相位解耦时，每个分量的半量子涡旋-反涡旋对诱导了两步 BKT 相变。另一方面，当两个分量的相位通过分量间的约瑟夫森耦合同步时，每个分量的两种涡旋会束缚形成分子，在这种情况下，我们发现只有通过分子-反分子对才有一个 BKT 相变。我们的结果可以通过两个弱连接的玻色系统来验证，例如具有拉比振荡的双分量超冷稀释玻色混合物和多能带超导体。
