彩色Δ_T噪声探测边缘模式的拓扑特性
Colored $Δ_T$ noise probes the topological character of edge modes
AI总结：
研究彩色Δ_T噪声作为量子霍尔和量子自旋霍尔系统中边缘模式输运探针，通过偏置协议和量子点接触研究其特性，能区分不同边缘模式，为识别介观拓扑系统边缘模式输运提供有力探针。
AI中文摘要：
我们研究了彩色Δ_T噪声，即有限频率的Δ_T噪声，作为量子霍尔和量子自旋霍尔系统中边缘模式（EM）输运的探针。彩色Δ_T噪声探测有限频率的非平衡电流涨落和动态输运特性，这些特性在直流电导和噪声测量中常常被掩盖。由于Δ_T噪声仅由零平均电荷电流条件下的温度和电压偏置驱动，它消除了电流诱导的焦耳热并直接探测固有热涨落。我们表明，手性、自旋守恒螺旋和自旋翻转螺旋（平凡）边缘模式在适当的偏置协议下表现出不同的彩色Δ_T噪声特征。通过量子点接触纳入能量依赖散射，我们证明电子-空穴不对称显著改变了有限频率谱，同时保留了这些区别特征。值得注意的是，彩色Δ_T噪声表现出频率依赖的符号反转，这在相应的白色（ω = 0）Δ_T噪声中不存在。我们进一步研究了零温度彩色量子散粒噪声，发现它对手性边缘模式完全消失，而自旋守恒螺旋响应随频率改变符号。相比之下，自旋翻转螺旋（平凡）边缘模式表现出正的彩色散粒噪声谱。然而，相应的彩色Δ_T噪声保留了其特征性的符号反转，为自旋守恒螺旋和自旋翻转螺旋（平凡）边缘模式输运提供了有力的区分。这些结果确立了彩色Δ_T噪声作为一种强大的、实验上可获取的、互补的探针，用于识别介观拓扑系统中的手性、自旋守恒螺旋和自旋翻转螺旋（平凡）边缘模式输运。
英文摘要：
We investigate colored $Δ_T$ noise, i.e., finite-frequency $Δ_T$ noise, as a probe of edge-mode (EM) transport in quantum Hall and quantum spin Hall systems. Colored $Δ_T$ noise probes finite-frequency nonequilibrium current fluctuations and dynamical transport properties that are often obscured in DC measurements of conductance and noise. Since $Δ_T$ noise is driven solely by a temperature and voltage bias under zero average charge current conditions, it eliminates current-induced Joule heating and directly probes intrinsic thermal fluctuations. We show that chiral, spin-conserving helical, and spin-flip helical (trivial) EMs exhibit distinct colored $Δ_T$-noise signatures under appropriate bias protocols. Incorporating energy-dependent scattering through a quantum point contact, we demonstrate that electron-hole asymmetry significantly modifies the finite-frequency spectrum while preserving these distinguishing features. Notably, colored $Δ_T$ noise exhibits a frequency-dependent sign reversal absent in the corresponding white ($ω=0$) $Δ_T$ noise. We further investigate zero-temperature colored quantum shot noise and find that it vanishes identically for chiral EMs, whereas the spin-conserving helical response changes sign with frequency. By contrast, spin-flip helical (trivial) EMs exhibit a positive colored shot-noise spectrum. However, the corresponding colored $Δ_T$ noise retains its characteristic sign reversal, providing a robust distinction between spin-conserving helical and spin-flip helical (trivial) EM transport. These results establish colored $Δ_T$ noise as a robust, experimentally accessible, complementary probe for identifying chiral, spin-conserving helical, and spin-flip helical (trivial) EM transport in mesoscopic topological systems.
