Xiang-Fa Zhou

Unconventional states of bosons with the synthetic spin–orbit coupling

The spin–orbit coupling with bosons gives rise to novel properties that are absent in usual bosonic systems. Under very general conditions, the conventional ground state wavefunctions of bosons are constrained by the ‘no-node’ theorem to be positive definite. In contrast, the linear dependence of the spin–orbit coupling leads to complex-valued condensate wavefunctions beyond this theorem. In this paper, we review the study of this class of unconventional Bose–Einstein condensations focusing on their topological properties. Both the 2D Rashba and 3D σ · p-type Weyl spin–orbit couplings give rise to Landau-level-like quantization of single-particle levels in the harmonic trap. Interacting condensates develop the half-quantum vortex structure spontaneously breaking the time-reversal symmetry and exhibit topological spin textures of the skyrmion type. In particular, the 3D Weyl coupling generates topological defects in the quaternionic phase space as an SU(2) generalization of the usual U(1) vortices. Rotating spin–orbit-coupled condensates exhibit rich vortex structures due to the interplay between vorticity and spin texture. In the Mott-insulating states in optical lattices, quantum magnetism is characterized by the Dzyaloshinskii–Moriya-type exchange interactions. (Some figures may appear in colour only in the online journal)

Magnetic phases of bosons with synthetic spin-orbit coupling in optical lattices

We investigate magnetic properties in the superfluid and Mott-insulating states of two-component bosons with spin-orbit (SO) coupling in two-dimensional square optical lattices. The spin-independent hopping integral

Quantum simulation of Heisenberg spin chains with next-nearest-neighbor interactions in coupled cavities

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Unitary transformations can be distinguished locally.

and SO coupled one

Vacancy defects in epitaxial La0.7Sr0.3MnO3thin films probed by a slow positron beam

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Nonlocal gate of quantum network via cavity quantum electrodynamics

are fitted from band-structure calculations in the continuum, which exhibit oscillations with increasing SO coupling strength. The magnetic superexchange model is derived in the Mott-insulating state with one particle per site, characterized by the Dzyaloshinsky-Moriya interaction. In the limit of

Two- and three-dimensional topological insulators with isotropic and parity-breaking Landau levels

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Dynamically Manipulating Topological Physics and Edge Modes in a Single Degenerate Optical Cavity

, we find a spin spiral Mott state whose pitch value is the same as that in the incommensurate superfluid state, while in the opposite limit

Unambiguous Discrimination of Mixed States: A Description Based on System-Ancilla Coupling

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Geometrical interpretation for robustness of entanglement

, the ground state exhibits a