论文标题
由密度依赖性PEIERLS诱导的蜂窝晶格中Rydberg激发的量子自旋液体
Quantum spin liquids of Rydberg excitations in a honeycomb lattice induced by density-dependent Peierls phases
论文作者
论文摘要
我们表明,在旋转轨道耦合的rydberg原子的二维蜂窝晶格中骨气激发的非线性转运会导致量子液相无序,这是量子自旋液体的候选物。正如[Lienhard等人最近所证明的那样。物理。 Rev. X,10,021031(2020)]自旋轨道耦合破坏了时间反转和手性的对称性,并导致硬核玻色子的可调密度依赖性复合物,或等效于复杂的XY XY自旋相互作用。使用精确的对角(ED),我们通过数值研究密度依赖性和直接传输项之间的竞争引起的相图。在平均场近似值中,当复合物跳跃的幅度超过直接的振幅时,相位从准方统计到120°相的相变。在完整模型中,由于复合跳跃的密度依赖性引起的量子波动,具有有限自旋隙的新阶段接近平均场临界点。我们表明,这个阶段是一个真正的无序阶段,具有非散发性的手性,其特征是非平凡的多体Chern数。具有多达28个晶格位点的小晶格的ED仿真指向非脱位基态,因此指向了由U(1)对称性保护的Bosonic Integer-Quantum Hall(BIQH)相。然而,C = 1的Chern数与无序的稳定性与BIQH阶段中的Chern数字有所不同。对于非常强大的非线性跳跃,我们发现了另一个无序的旋转缝隙。该阶段还具有较大的自旋手性,并且可能是无间隙的自旋液体,但位于Rydberg系统中可访问的参数方案之外。
We show that the nonlinear transport of bosonic excitations in a two-dimensional honeycomb lattice of spin-orbit coupled Rydberg atoms gives rise to disordered quantum phases which are candidates for quantum spin liquids. As recently demonstrated in [Lienhard et al. Phys. Rev. X, 10, 021031 (2020)] the spin-orbit coupling breaks time-reversal and chiral symmetries and leads to a tunable density-dependent complex hopping of the hard-core bosons or equivalently to complex XY spin interactions. Using exact diagonalization (ED) we numerically investigate the phase diagram resulting from the competition between density-dependent and direct transport terms. In mean-field approximation there is a phase transition from a quasi-condensate to a 120° phase when the amplitude of the complex hopping exceeds that of the direct one. In the full model a new phase with a finite spin gap emerges close to the mean-field critical point as a result of quantum fluctuations induced by the density-dependence of the complex hopping. We show that this phase is a genuine disordered one, has a non-vanishing spin chirality and is characterized by a non-trivial many-body Chern number. ED simulations of small lattices with up to 28 lattice sites point to a non-degenerate ground state and thus to a bosonic integer-quantum Hall (BIQH) phase, protected by U(1) symmetry. The Chern number of C = 1, which is robust to disorder, is however different from the even Chern numbers found in BIQH phases. For very strong, nonlinear hoppings of opposite sign we find another disordered regime with vanishing spin gap. This phase also has a large spin chirality and could be a gapless spin-liquid but lies outside the parameter regime accessible in the Rydberg system.