Photocurrent, Rectification, and Magnetic Field Symmetry of Induced Current Through Quantum Dots

TL;DR

This study investigates mesoscopic current generation in chaotic quantum dots under high-frequency ac excitation, revealing magnetic field asymmetry at GHz frequencies and symmetry at MHz, highlighting different underlying mechanisms.

Contribution

It demonstrates the frequency-dependent symmetry properties of induced currents in quantum dots, confirming theoretical predictions at high frequencies and identifying rectification effects at low frequencies.

Findings

Induced current fluctuations are asymmetric in magnetic field at GHz frequencies.

Conductance remains symmetric in magnetic field across frequencies.

At MHz frequencies, induced current is symmetric, indicating rectification.

Abstract

We report mesoscopic dc current generation in an open chaotic quantum dot with ac excitation applied to one of the shape-defining gates. For excitation frequencies large compared to the inverse dwell time of electrons in the dot (i.e., GHz), we find mesoscopic fluctuations of induced current that are fully asymmetric in the applied perpendicular magnetic field, as predicted by recent theory. Conductance, measured simultaneously, is found to be symmetric in field. In the adiabatic (i.e., MHz) regime, in contrast, the induced current is always symmetric in field, suggesting its origin is mesoscopic rectification.