Symmetry-broken states in a system of interacting bosons on a two-leg ladder with a uniform Abelian gauge field
Symmetry-broken states in a system of interacting bosons on a two-leg ladder with a uniform Abelian gauge field
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DOI：
10.1103/physreva.94.063628
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发表时间：
2016-10
影响因子：
2.9
通讯作者：
S. Greschner;M. Piraud;F. Heidrich-Meisner;I. McCulloch;U. Schollwöck;T. Vekua
中科院分区：
文献类型：
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作者：
S. Greschner;M. Piraud;F. Heidrich-Meisner;I. McCulloch;U. Schollwöck;T. Vekua
研究了在均匀阿贝尔规范场作用下，两条腿阶梯上具有排斥接触相互作用的玻色子的量子相位。该模型实现了许多有趣的状态，包括迈斯纳相，涡旋流体，涡旋晶格，电荷密度波，和偏置阶梯相。我们的工作集中在这些状态的子集，打破了离散对称性。我们使用密度矩阵重整化群模拟来证明在不同的涡旋密度下存在三个涡旋晶格态，并且我们表征了从这些相到相邻态的相变。此外，我们提供了一个直观的解释的手征电流反转效应，是绑在这些涡旋晶格。我们还研究了存在于1/4粒子填充处的电荷密度波态，其相互作用强度很大，通量值接近通量量子的一半。通过改变系统参数，该状态可以过渡到完全带隙的涡格Mott绝缘状态。我们阐明了这些阶段的稳定性，对最近邻相互作用的阶梯相关的实验实现与合成晶格尺寸。在1/3粒子填充的电荷密度波状态可以稳定的通量值接近一半的通量量子和非常强的现场相互作用中存在的强烈排斥的梯级。最后，我们分析地描述了这些阶段在低密度区的出现，特别是，我们得到了偏置阶梯阶段的边界，即，该阶段的特点是腿之间的密度不平衡。我们联系最近的量子气体实验，实现了相关的模型，并讨论这些量子态的实验可观察到的签名。
We study the quantum phases of bosons with repulsive contact interactions on a two-leg ladder in the presence of a uniform Abelian gauge field. The model realizes many interesting states, including Meissner phases, vortex fluids, vortex lattices, charge density waves, and the biased-ladder phase. Our work focuses on the subset of these states that breaks a discrete symmetry. We use density matrix renormalization group simulations to demonstrate the existence of three vortex-lattice states at different vortex densities and we characterize the phase transitions from these phases into neighboring states. Furthermore, we provide an intuitive explanation of the chiral-current reversal effect that is tied to some of these vortex lattices. We also study a charge-density-wave state that exists at 1/4 particle filling at large interaction strengths and flux values close to half a flux quantum. By changing the system parameters, this state can transition into a completely gapped vortex-lattice Mott-insulating state. We elucidate the stability of these phases against nearest-neighbor interactions on the rungs of the ladder relevant for experimental realizations with a synthetic lattice dimension. A charge-density-wave state at 1/3 particle filling can be stabilized for flux values close to half a flux quantum and for very strong on-site interactions in the presence of strong repulsion on the rungs. Finally, we analytically describe the emergence of these phases in the low-density regime, and, in particular, we obtain the boundaries of the biased-ladder phase, i.e., the phase that features a density imbalance between the legs. We make contact with recent quantum-gas experiments that realized related models and discuss signatures of these quantum states in experimentally accessible observables.