Photo-assisted shot noise in the fractional quantum Hall regime
The effect of an ac perturbation on the shot noise of a fractional quantum Hall fluid is studied at finite temperature. For a normal metal, it is known that the zero‐frequency noise derivative exhibits steps as a function of bias voltage. In contrast, at Laughlin fractions, the backscattering noise exhibits evenly spaced singularities, which are reminiscent of tunneling density‐of‐states singularities for quasiparticles. The spacing is determined by the quasiparticle charge ve and the ratio of the dc bias with respect to the drive frequency. Photo‐assisted transport can thus be considered as a probe for effective charges of the quantum Hall effect.