Colored ΔT noise probes the topological character of edge modes
Abstract
We investigate colored ΔT noise, i.e., finite-frequency ΔT noise, as a probe of edge-mode (EM) transport in quantum Hall and quantum spin Hall systems. Colored ΔT noise probes finite-frequency nonequilibrium current fluctuations and dynamical transport properties that are often obscured in DC measurements of conductance and noise. Since ΔT 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 ΔT-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 ΔT noise exhibits a frequency-dependent sign reversal absent in the corresponding white (ω=0) ΔT 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 ΔT 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 ΔT 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.
Versions
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BibTeX
@misc{mishra2026colored,
title = {{Colored $Δ_T$ noise probes the topological character of edge modes}},
author = {Sachiraj Mishra and Colin Benjamin},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2607.17354},
eprint = {2607.17354},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2607.17354},
note = {CC BY-NC-ND 4.0},
}
RIS
TY - UNPB
TI - Colored Δ_T noise probes the topological character of edge modes
AU - Sachiraj Mishra
AU - Colin Benjamin
PY - 2026
DA - 2026/08/10
PB - arXiv
DO - 10.48550/arxiv.2607.17354
UR - https://arxiv.org/abs/2607.17354
AB - 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.
ER -