Energy Relaxation in the Integer Quantum Hall Regime

TL;DR

This study explores energy exchange mechanisms in integer quantum Hall edge channels, revealing efficient inter-channel energy redistribution without particle transfer and unexpected thermalization behavior over micrometer scales.

Contribution

It demonstrates that energy relaxation occurs efficiently between edge channels without particle exchange, challenging quasiparticle localization models in quantum Hall systems.

Findings

No energy transfer to thermalized states observed.

Efficient energy redistribution between channels without particle exchange.

Long-distance energy distribution resembles a lower-temperature hot Fermi function.

Abstract

We investigate the energy exchanges along an electronic quantum channel realized in the integer quantum Hall regime at filling factor $\nu_L=2$. One of the two edge channels is driven out-of-equilibrium and the resulting electronic energy distribution is measured in the outer channel, after several propagation lengths $0.8~\mu$m$\leq L\leq30~\mu$m. Whereas there are no discernable energy transfers toward thermalized states, we find efficient energy redistribution between the two channels without particle exchanges. At long distances $L\geq10~\mu$m, the measured energy distribution is a hot Fermi function whose temperature is lower than expected for two interacting channels, which suggests the contribution of extra degrees of freedom. The observed short energy relaxation length challenges the usual description of quantum Hall excitations as quasiparticles localized in one edge channel.