周期驱动量子系统淬火动力学中的拓扑特征
Topological signatures in the quench dynamics of periodically driven quantum systems
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中文总结 AI 辅助
该研究分析了耦合费米子浴的石墨烯在圆偏振光淬火后的动力学，揭示了其电流的拓扑特征，通过紧束缚模型计算验证了量子化电导与边缘模式数量的关联。
中文摘要 AI 辅助
我们研究了石墨烯（含与不含交错质量项）在圆偏振光突然开启后的淬火动力学，同时考虑了其与费米子浴的耦合。我们采用扶手椅型纳米带，计算了连续频闪时刻边缘附近的周期平均键电流。对于孤立系统，电流围绕直流值振荡，我们通过解析证明该值等于弗洛凯（Floquet）带电流按其投影占据数加权后的结果；非零直流电流标志着诱导的拓扑相。当与有限耦合的浴耦合时，电流和电导先增大后饱和，表明达到非平衡稳态。在耦合趋于零的极限下，周期平均电导在对浴化学势（由驱动频率的整数倍偏移）求和后呈现量子化，揭示了穿越零准能隙和弗洛凯区边界隙的边缘模式数量。我们通过计算有限尺寸紧束缚模型在三步驱动协议下的两端口电导来验证这些结果；应用求和规则后的键电导证实了我们的发现。
英文摘要
We study the quench dynamics of graphene, without and with a staggered mass, following the sudden switch-on of circularly polarized light where coupling to a fermionic bath is also considered. Using an armchair nanoribbon, we compute the period-averaged bond current near the edge at successive stroboscopic times. For the isolated system, the current oscillates around a dc value which, we analytically show, equals the Floquet band currents weighted by their projected occupations; a nonzero dc current signals an induced topological phase. When coupled to a bath with a finite coupling, the current and conductance initially increase and then saturate, indicating a nonequilibrium steady state. In the limit of vanishingly small coupling, the period-averaged conductance becomes quantized after summing over bath chemical potentials shifted by integer multiples of the driving frequency, revealing the number of edge modes crossing the zero-quasienergy gap and the Floquet zone boundary gap. We support these results by computing the two-terminal conductance of a finite-size tight-binding model under a three-step driving protocol; the bond conductance after applying the sum rule corroborates our findings.
