Low-frequency noise of quantum point contacts in the ballistic and quantum Hall regime

Abstract

The low-frequency resistance noise of quantum point contacts is shown to be dominated by fluctuations in the electrostatic potential. Both in the ballistic and in the quantum Hall regime, the noise is strongly suppressed if the conductance is quantized. The suppression is enhanced by a strong magnetic field due to the absence of backscattering in the point contact. Additional minima are found in the noise as a function of the conductance due to the lifting of the spin degeneracy by the field.