Antiferromagnetic self-ordering of a Fermi gas in a ring cavity
Antiferromagnetic self-ordering of a Fermi gas in a ring cavity
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DOI：
10.1088/1367-2630/ab151e
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发表时间：
2018-11
影响因子：
3.3
通讯作者：
E. Colella;S. Ostermann;Wolfang Niedenzu;F. Mivehvar;H. Ritsch
中科院分区：
文献类型：
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作者：
E. Colella;S. Ostermann;Wolfang Niedenzu;F. Mivehvar;H. Ritsch
我们研究了受驱动的自旋1/2无碰撞费米子原子与环形谐振器电磁场耦合的密度和自旋自旋自序。这两个自旋态是通过一对简并的反向传播腔模和两个横向泵浦光场的双光子喇曼耦合。在这种一维组态中，耦合原子-光场系统具有连续的U(1)平移对称性和离散的Z2自旋反转对称性。对于足够强的泵浦强度，在半填充状态下，U(1)×Z2对称性在超辐射相变到具有自旋结构和自旋密度的态的开始时自发破缺。我们主要发现在腔波长处有一个反铁磁晶格有序。在具有相反自旋的费米子之间，自序态显示出意外的正动量对关联。当泵浦强度较高时，这些由腔介导的关联消失。
We explore the density and spin self-ordering of driven spin-1/2 collisionless fermionic atoms coupled to the electromagnetic fields of a ring resonator. The two spin states are two-photon Raman-coupled via a pair of degenerate counterpropagating cavity modes and two transverse pump fields. In this one-dimensional configuration the coupled atom-field system possesses a continuous U(1) translational symmetry and a discrete Z2 spin inversion symmetry. At half filling for sufficiently strong pump strengths, the combined U(1) × Z2 symmetry is spontaneously broken at the onset of a superradiant phase transition to a state with self-ordered density and spin structures. We predominately find an antiferromagnetic lattice order at the cavity wavelength. The self-ordered states exhibit unexpected positive momentum pair correlations between fermions with opposite spin. These strong cavity-mediated correlations vanish at higher pump strength.