Dynamically broken symmetry in periodically gated quantum dots: Charge accumulation and dc-current

TL;DR

This paper investigates how periodic modulations affect charge transport and current in quantum dot systems, revealing the role of symmetry breaking and sideband effects in quantum pumping.

Contribution

It provides analytical relations for dc-current and charge accumulation in periodically driven quantum dots, highlighting the impact of symmetry breaking on quantum pumping.

Findings

Sideband peaks relate to combination frequencies of modulations

Charge pumping occurs due to broken symmetry without bias voltages

Analytical expressions for current and charge in zero-temperature limit

Abstract

Time-dependent electron transport through a quantum dot and double quantum dot systems in the presence of polychromatic external periodic quantum dot energy-level modulations is studied within the time evolution operator method for a tight-binding Hamiltonian. Analytical relations for the dc-current flowing through the system and the charge accumulated on a quantum dot are obtained for the zero-temperature limit. It is shown that in the presence of periodic perturbations the sideband peaks of the transmission are related to combination frequencies of the applied modulations. For a double quantum dot system under the influence of polychromatic perturbations the quantum pump effect is studied in the absence of source-drain and static bias voltages. In the presence of spatial symmetry the charge is pumped through the system due to broken generalized parity symmetry.