Interband Coherence Induced Correction to Adiabatic Pumping in Periodically Driven Systems

TL;DR

This paper investigates how interband coherence affects adiabatic pumping in periodically driven systems, revealing a correction term beyond traditional adiabatic theory, with implications for understanding topological phases and coherence effects.

Contribution

It introduces a correction to adiabatic pumping due to interband coherence in Floquet systems, extending the quantum adiabatic theorem for driven topological phases.

Findings

Interband coherence induces a correction to adiabatic displacement.

The correction persists in the adiabatic limit due to coherence.

The theory is validated using a topological superlattice model.

Abstract

Periodic driving can create topological phases of matter absent in static systems. In terms of the displacement of the position expectation value of a time-evolving wavepacket in a closed system, a type of adiabatic dynamics in periodically driven systems is studied for general initial states possessing coherence between different Floquet bands. Under one symmetry assumption, the displacement of the wavepacket center over one adiabatic cycle is found to be comprised by two components independent of the time scale of the adiabatic cycle: a weighted integral of the Berry curvature summed over all Floquet bands, plus an interband coherence induced correction. The found correction is beyond a naive application of the quantum adiabatic theorem but survives in the adiabatic limit due to interband coherence. Our theoretical results are hence of general interest towards an improved understanding of the quantum adiabatic theorem. Our theory is checked using a periodically driven superlattice model with nontrivial topological phases. In addition to probing topological phase transitions, the adiabatic dynamics studied in this work is now also anticipated to be useful in manifesting coherence and decoherence effects in the representation of Floquet bands.