Scattering of Bunched Fractionally Charged Quasiparticles

TL;DR

This paper reports the discovery of temperature-dependent bunching of fractional quasiparticles in the fractional quantum Hall effect, revealing new low-temperature backscattering states with distinct charges and energy characteristics.

Contribution

It uncovers temperature-induced bunching phenomena of fractional quasiparticles and identifies separate backscattering states with unique charge and energy properties.

Findings

Bunching of fractional charges occurs at very low temperatures.

Backscattered charges depend on temperature and filling factor.

Distinct temperature dependence of backscattered current was observed.

Abstract

The charge of fractionally charged quasiparticles, proposed by Laughlin to explain the fractional quantum Hall effect (FQHE), was recently verified by measurements. Charge q=e/3 and e/5 (e is the electron charge), at filling factors nu=1/3 and 2/5, respectively, were measured. Here we report the unexpected bunching of fractional charges, induced by an extremely weak backscattering potential at exceptionally low electron temperatures (T<10 mK) - deduced from shot noise measurements. Backscattered charges q=nu e, specifically, q=e/3, q=2e/5, and q<3e/7, in the respective filling factors, were measured. For the same settings but at an only slightly higher electron temperature, the measured backscattered charges were q=e/3, q=e/5, and q=e/7. In other words, bunching of backscattered quasiparticles is taking place at sufficiently low temperatures. Moreover, the backscattered current exhibited distinct temperature dependence that was correlated to the backscattered charge and the filling factor. This observation suggests the existence of 'low' and 'high' temperature backscattering states, each with its characteristic charge and characteristic energy.