Time domain braiding of anyons revealed through a nonequilibrium fluctuation dissipation theorem

Abstract: We derive a novel fluctuation--dissipation theorem (FDT) valid for nonequilibrium initial states that imprint the braiding of anyons in the time domain. The derivation is carried out within the Unifying Nonequilibrium Perturbative Theory (UNEPT), which applies to both standard reservoir geometries and configurations with one or two quantum point contacts (QPCs) injecting dilute anyonic fluxes. Based on this FDT, we propose complementary methods to determine the time-domain braiding phase. The first method relates the DC backscattering noise to the integral of the current with respect to DC drives, while the second connects the AC current phase shift to the DC noise. The latter provides a particularly robust probe of the statistical angle $\theta$, offering an intrinsic calibration and cancelling certain nonuniversal renormalization effects. Specializing to a thermalized Tomonaga--Luttinger liquid (TLL), we further show that in the quantum regime the phase shift enables a direct determination of the scaling dimension $\delta$ when $\delta > 1/2$. These results define experimentally accessible schemes to extract either $\theta$ or $\delta$ in minimal single-QPC setups, without relying on interferometry or cross-correlation measurements.