Observation of Neutral Modes In The Fractional Quantum Hall Effect Regime.

We report on the first experimental observation of neutral modes in particle-hole conjugate fractional quantum Hall states using shot noise measurements. The presence of the neutral modes, in addition to producing excess noise in a quantum point contact (QPC), was seen to affect strongly the charge of the tunneling quasiparticles of the charge mode in the QPC and to increase their apparent temperature. The observation of an upstream neutral mode in the 5/2 state may constitute an added indication of its non-abelian nature. [ABSTRACT FROM AUTHOR]