Department of Physics, Stanford University, Stanford, California 94305, USA.
E. L. Ginzton Laboratory, Stanford University, Stanford, California 94305, USA.
Phys Rev Lett. 2018 Oct 19;121(16):163601. doi: 10.1103/PhysRevLett.121.163601.
We observe the joint spin-spatial (spinor) self-organization of a two-component Bose-Einstein condensate (BEC) strongly coupled to an optical cavity. This unusual nonequilibrium Hepp-Lieb-Dicke phase transition is driven by an off-resonant Raman transition formed from a classical pump field and the emergent quantum dynamical cavity field. This mediates a spinor-spinor interaction that, above a critical strength, simultaneously organizes opposite spinor states of the BEC on opposite checkerboard configurations of an emergent 2D lattice. The resulting spinor density-wave polariton condensate is observed by directly detecting the atomic spin and momentum state and by holographically reconstructing the phase of the emitted cavity field. The latter provides a direct measure of the spin state, and a spin-spatial domain wall is observed. The photon-mediated spin interactions demonstrated here may be engineered to create dynamical gauge fields and quantum spin glasses.
我们观察到两分量玻色-爱因斯坦凝聚体（BEC）与光学腔强烈耦合后的自旋-空间（旋量）自组织。这种非平衡的 Hepp-Lieb-Dicke 相变是由一个由经典泵浦场和新兴量子动力学腔场形成的非共振拉曼跃迁驱动的。这介导了一种旋量-旋量相互作用，在超过临界强度后，同时将 BEC 的相反旋量态组织在新兴二维晶格的相反棋盘配置上。通过直接检测原子自旋和动量状态，并通过对发射腔场的相位进行全息重建，观察到了旋量密度波极化激元凝聚体。后者提供了对自旋状态的直接测量，并观察到了自旋-空间畴壁。这里演示的光子介导的自旋相互作用可以被设计用来创建动态规范场和量子自旋玻璃。
