Browsing by Author "Zhou, Xiang-Fa"

Now showing 1 - 5 of 5
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    Dynamically Manipulating Topological Physics and Edge Modes in a Single Degenerate Optical Cavity
    (American Physical Society, 2017) Zhou, Xiang-Fa; Luo, Xi-Wang; Wang, Su; Guo, Guang-Can; Zhou, Xingxiang; Pu, Han; Zhou, Zheng-Wei; Rice Center for Quantum Materials
    We propose a scheme to simulate topological physics within a single degenerate cavity, whose modes are mapped to lattice sites. A crucial ingredient of the scheme is to construct a sharp boundary so that the open boundary condition can be implemented for this effective lattice system. In doing so, the topological properties of the system can manifest themselves on the edge states, which can be probed from the spectrum of an output cavity field. We demonstrate this with two examples: a static Su-Schrieffer-Heeger chain and a periodically driven Floquet topological insulator. Our work opens up new avenues to explore exotic photonic topological phases inside a single optical cavity.
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    Engineering and revealing Dirac strings in spinor condensates
    (American Physical Society, 2024) Xu, Gui-Sheng; Jain, Mudit; Zhou, Xiang-Fa; Guo, Guang-Can; Amin, Mustafa A.; Pu, Han; Zhou, Zheng-Wei
    Artificial monopoles have been engineered in various systems, yet there has been no systematic study of the singular vector potentials associated with the monopole field. We show that the Dirac string, the line singularity of the vector potential, can be engineered, manipulated, and made manifest in a spinor atomic condensate. We elucidate the connection among spin, orbital degrees of freedom, and the artificial gauge, and show that there exists a mapping between the vortex filament and the Dirac string. We also devise a proposal where preparing initial spin states with relevant symmetries can result in different vortex patterns, revealing an underlying correspondence between the internal spin states and the spherical vortex structures. Such a mapping also leads to a new way of constructing spherical Landau levels, and monopole harmonics. Our observation provides insights into the behavior of quantum matter possessing internal symmetries in curved spaces.
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    Synthetic Landau Levels and Spinor Vortex Matter on a Haldane Spherical Surface with a Magnetic Monopole
    (American Physical Society, 2018) Zhou, Xiang-Fa; Wu, Congjun; Guo, Guang-Can; Wang, Ruquan; Pu, Han; Zhou, Zheng-Wei
    We present a flexible scheme to realize exact flat Landau levels on curved spherical geometry in a system of spinful cold atoms. This is achieved by applying the Floquet engineering of a magnetic quadrupole field to create a synthetic monopole field in real space. The system can be exactly mapped to the electron-monopole system on a sphere, thus realizing Haldane's spherical geometry for fractional quantum Hall physics. This method works for either bosons or fermions. We investigate the ground-state vortex pattern for an s-wave interacting atomic condensate by mapping this system to the classical Thompson's problem. The distortion and stability of the vortex pattern are further studied in the presence of dipolar interaction. Our scheme is compatible with the current experimental setup, and may serve as a promising route of investigating quantum Hall physics and exotic spinor vortex matter on curved space.
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    Two-component Bose-Hubbard model in an array of cavity polaritons
    (American Physical Society, 2015) Zhang, Yong-Chang; Zhou, Xiang-Fa; Zhou, Xingxiang; Guo, Guang-Can; Pu, Han; Zhou, Zheng-Wei
    We propose a scheme which can realize an extended two-component Bose-Hubbard model using polaritons confined in an array of optical cavities. In addition to the density-dependent interactions, this model also contains nonlinear coupling terms between the two components of the polariton. Using a mean-field calculation, we obtain the phase diagram which shows how these terms affect the transition between the Mott insulator and the superfluid phase. In addition, we employ both a perturbation approach and an exact diagonalization method to gain more insights into the phase diagram.
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    Two-component polariton condensate in an optical microcavity
    (American Physical Society, 2014) Zhang, Yong-Chang; Zhou, Xiang-Fa; Guo, Guang-Can; Zhou, Xingxiang; Pu, Han; Zhou, Zheng-Wei; Rice Quantum Institute
    We present a scheme for engineering the extended two-component Bose-Hubbard model using polariton condensate supported by an optical microcavity. Compared to the usual two-component Bose-Hubbard model with only Kerr nonlinearity, our model includes a nonlinear tunneling term which depends on the number difference of the particle in the two modes. In the mean-field treatment, this model is an analog to a nonrigid pendulum with a variable pendulum length whose sign can be also changed. We study the dynamic and groundstate properties of this model and show that there exists a first-order phase transition as the strength of the nonlinear tunneling rate is varied. Furthermore, we propose a scheme to obtain the polariton condensate wave function.