Optimization of electron pumping by harmonic mixing

TL;DR

This paper investigates how harmonic mixing in an external ac-field can induce and optimize a non-zero average current in a symmetric quantum bridge, using time- and energy-domain quantum methods.

Contribution

It introduces a combined time- and energy-domain approach to analyze electron pumping with harmonic mixing, revealing how to optimize the pump current by tuning harmonic amplitudes.

Findings

Harmonic mixing breaks parity, enabling a non-zero average current.

Optimal amplitude ratio maximizes the pump current.

Theoretical methods provide insights into quantum electron pumping mechanisms.

Abstract

For a symmetric bridge coupled to infinite leads, in the presence of a dipole-coupled external ac-field with harmonic mixing, we solve the Schr\"odinger equation in the time-domain using open boundary conditions as well as in the energy-domain using Floquet scattering theory. As this potential breaks parity and generalized parity, we find a non-vanishing average current. We then optimize the relative amplitude ratio between the fundamental and the second harmonic leading to a maximum in the pump current.