$Δ_T$ Noise as a Robust Diagnostic for Chiral, Helical and Trivial Edge Modes
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Abstract
In this article we demonstrate that $Δ_T$ noise provides a sensitive, practical probe for distinguishing chiral edge modes from topological helical and trivial (non-topological) helical edge transport. Measured under zero-current conditions, $Δ_T$ noise reveals contrasts that conventional conductance measurements typically miss. Crucially, $Δ_T$ requires no external energy input in the form of an applied voltage bias, yet encodes the same intrinsic information that shot noise yields in the zero-temperature, finite-bias limit, without the distorting effects of Joule heating. This absence of bias-induced heating makes $Δ_T$ noise both more precise and more reliable than conventional shot-noise approaches. Moreover, the diagnostic power of $Δ_T$ noise persists at finite frequencies $ω$ too. The frequency-dependent signal $Δ_{T}(ω)$ exhibits distinctive spectral signatures (including sign changes) that further enhance its utility as an experimentally accessible fingerprint of edge-mode topology.