| 交错跃迁Hofstadter梯子的量子流相 |
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| 引用本文： | 刘彪,周晓凡,陈刚,贾锁堂.交错跃迁Hofstadter梯子的量子流相[J].物理学报,2020(8):50-57. |
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| 作者姓名： | 刘彪 周晓凡 陈刚 贾锁堂 |
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| 作者单位： | 山西大学激光光谱研究所;山西大学;山东师范大学物理与电子科学学院 |
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| 基金项目： | 国家重点研发计划(批准号:2017YFA0304203);国家自然科学基金(批准号:11674200,11804204);教育部长江学者和创新团队发展计划(批准号:IRT13076);山西省“1331工程”重点学科建设计划资助的课题。 |
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| 摘 要： | 为玻色Hofstadter梯子模型引入交错跃迁,来扩展模型支持的量子流相.基于精确对角化和密度矩阵重整化群计算发现,无相互作用时,系统中包含横流相、涡旋相和纵流相;横流相来自均匀跃迁时Hofstadter梯子模型的Meissner相,纵流相是交错跃迁时才可见的流相.强相互作用极限下系统的超流区也包含横流相、纵流相和涡旋相,但存在更多的相变级数;超流区的横流相、纵流相之间存在相变但Mott区的不存在,把Mott区的"横、纵流相"称为Mott-均匀相,在Mott区只存在均匀相和涡旋相.跃迁的交错会压缩涡旋相存在的区域,使Mott区最终只剩下均匀相;跃迁的交错不仅能驱动Mott-超流相变,还使磁通的改变也能够驱动系统的Mott-超流相变.对这一系统的研究丰富了磁通系统中的量子流相,同时为研究拓扑流特性提供了模型支持.
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| 关 键 词： | 量子相变 数值模拟 Hofstadter梯子 手性流 |
Current phases in Hofstadter ladder with staggered hopping |
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| Liu Biao,Zhou Xiao-Fan,Chen Gang,Jia Suo-Tang.Current phases in Hofstadter ladder with staggered hopping[J].Acta Physica Sinica,2020(8):50-57. |
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| Authors: | Liu Biao Zhou Xiao-Fan Chen Gang Jia Suo-Tang |
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| Affiliation: | (State Key Laboratory of Quantum Optics and Quantum Optics Devices,Institute of Laser Spectroscopy,Shanxi University,Taiyuan 030006,China;Collaborative Innovation Center of Extreme Optics,Shanxi University,Taiyuan 030006,China;Center of Light Manipulations and Applications,College of and Electronics,Shandong Normal University,Jinan 250358,China) |
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| Abstract: | Hofstadter ladder describes a Boson ladder under a uniform magnetic field and supports nontrivial energy band and fractional quantum Hall states. Staggered hopping is illuminated from the SSH model and proved to have non-trivial effects on current phases. We introduce staggered hopping on Hofstadter ladder to study the novel current phases. Exact diagonalization(ED) and density matrix renormalization group(DMRG) methods have been employed to study the current phases of the ladder in noninteraction and strong interaction(hard core boson) cases. By observing energy singularities and the new flux patterns when increasing the staggered hopping strength, we extend Meissner and vortex phase to horizontal current phase, vertical current phase and vortex phase. The horizontal current phase has stronger chiral currents in horizontal direction, which is the long direction of the ladder. The vertical current phase has stronger chiral currents in vertical direction. The above two phases do not break translational invariance while the vortex phase does. The current patterns of horizontal current phase are proved to be continuously deformed form the Meissner phase, and the vortex phase has similar signatures. The vertical current phase is only visible when the hopping is staggered. These phases generally exist in noninteraction regimes and interacting superfluid regimes. We have defined new quantities(i.e. current inhomogeneity and nearest overlap) to characterize different quantum phases. In noninteraction case, the horizontal current phase go through the vortex phase to enter the vertical current phase by second order phase transitions, but in strong interaction case such a change can be directly made in a first order phase transition. The direct transition is made in higher fillings with almost identical flux. Surprisingly, the three phases turn into only two phases in Mott regimes, and the phase transition between the horizontal current phase and the vertical current phase has disappeared. We call the new phase as Mott-homogenous phase. The staggered hopping has exotic effects in strong interaction case. For n = 0.25 filling, the staggered hopping shrinks the region of vortex phases and produces Mott-SF transition. When the staggered hopping is weak, the system achieves Mott-SF transition just by varying the flux. This research can enrich current phases in lattice systems and illuminate further studies on chiral currents. |
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| Keywords: | quantum phase transition numerical simulation Hofstadter ladder chiral current |
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