报告题目：
Supersolid phase and Berezinsky-Kosterlitz-Thouless phase transition in a dipolar Fermi gas
报告时间：3月10日（周四）下午15：00
报告地点：物理楼新楼五楼多功能报告厅
报告人： Dr. Zhigang Wu （University of Aarhus, Denmark）
报告摘要：
We study a two-dimensional spin-polarized Fermi gas with electric dipoles aligned by an external electric field. This system is known to exhibit three stable phases, namely the normal Fermi liquid, the p-wave superfluid and the density wave phase (stripe phase). Our studies focus on two aspects of the phase diagram. First we investigate the possibility of a new zero-temperature phase in which the density wave order and the superfluid order coexist. We find that the system in the density wave phase eventually becomes unstable towards pairing as the tilting angle of the dipoles increases and the dipolar interaction becomes more attractive. Importantly, the resulting superfluid order does not destroy the density wave order, making the system a type of supersolid. We discuss possible experimental methods by which such a phase can be detected. The second part of our study concerns the finite temperature phase transition of the stripe phase. This phase can be viewed as the quantum analogue of the classical liquid crystal phase found in electronic materials. We base our analysis on the elastic energy of the system, in which the stiffness constants are determined using the self-consistent Hartree-Fock theory. The melting of this phase is driven by the proliferation of topological defects called dislocations via the so-called Berezinskii-Kosterlitz-Thouless (BKT) mechanism. We calculate the BKT critical temperature by the well-known renormalisation group equations.
[1] Z. Wu, J. K. Block and G. M. Bruun, Phys. Rev. B 91, 224504 (2015).
[2] Z. Wu, J. K. Block and G. M. Bruun, Scientific Reports 6, 19038 (2016).
报告人简历：
Postdoctoral fellow, Aarhus University, Denmark, Since May 2014.
Postdoctoral fellow, Queen’s University, Canada, May 2013 - April 2014.
Ph.D. Physics, Queen’s University, Canada, 2009 - 2013.
M.S. Physics, Peking University, China, 2005-2007.
B.S. Physics, Wuhan University, China, 2000-2004.
邀请人： 张文献教授
