Directed electron transport through ballistic quantum dot under microwave radiation

TL;DR

This study demonstrates microwave-induced directed electron transport in a ballistic quantum dot, revealing magnetic field effects and proposing a ballistic model to explain the nonlinear rectification phenomena.

Contribution

It provides experimental evidence of microwave rectification in ballistic quantum dots and introduces a ballistic model to explain the observed nonlinear directed transport.

Findings

Rectification observed at 1-40 GHz and 0.3K-6K.

Magnetic fields suppress rectification when Larmor radius is smaller than dot size.

Behavior varies with microwave frequency and magnetic field.

Abstract

Rectification of microwave radiation by asymmetric, ballistic quantum dot is observed. The directed transport is studied at different frequency (1-40 GHz) temperatures (0.3K-6K)and magnetic field. Dramatic reduction of the rectification is found in magnetic fields at which the cyclotron (Larmor) radius of the electron orbits at Fermi level is smaller than the size of the quantum dot. It strongly suggests the ballistic nature of the observed nonlinear phenomena. Both symmetric and anti-symmetric with respect to the magnetic field contributions to the directed transport are presented. We have found that the behavior of the symmetric part of the rectified voltage with the magnetic field is different significantly for microwaves with different frequencies. A ballistic model of the directed transport is proposed.