Scattering of bunched fractionally charged quasiparticles

We report the unexpected bunching of Laughlin's quasiparticles, induced by an extremely weak backscattering potential at exceptionally low electron temperatures (T<10 mK), deduced from shot noise measurements. Backscattered charges q=nue, specifically, q=e/3, q=2e/5, and q<3e/7, in the respective filling factors, were measured. For the same settings but at a slightly higher electron temperature, the measured backscattered charges were q=e/3, q=e/5, and q=e/7, as expected. 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 energy.