Symmetry-induced even/odd parity in charge and heat pumping

TL;DR

This paper demonstrates how discrete symmetries in Floquet systems determine the parity of charge and heat pumping with respect to the reservoir's chemical potential, providing a simple criterion for flow direction control.

Contribution

It reveals the relationship between symmetries and the parity of charge and heat pumping, extending to various unitary symmetries and illustrating with models.

Findings

Charge pumping is odd in μ under particle-hole symmetry.

Heat pumping is even in μ under particle-hole symmetry.

Symmetry considerations can reverse or maintain flow direction.

Abstract

It is shown that the presence of discrete symmetries in Floquet systems connected to metallic reservoirs imprints a definite parity on the charge and heat pumping as a function of the reservoir's chemical potential, $\mu$. In particular, when particle-hole symmetry (PHS) holds, the pumping of charge (heat) is an odd (even) function of $\mu$. Whereas, if only the product of PHS and parity symmetry is present, pumping of charge (heat) is even (odd) in $\mu$. Our results also extend to the presence of other unitary symmetries and provide a simple criterion for reversing (or maintaining) the direction of the flow. We illustrate our findings using two variants of the Su-Schrieffer-Heeger model under a time-periodic perturbation.