Floquet-Landau-Zener interferometry: Usefulness of the Floquet theory in pulse-laser-driven systems

TL;DR

This paper develops a Floquet-Landau-Zener interferometry approach to analyze pulse-laser-driven quantum systems, demonstrating its effectiveness in predicting excitation probabilities even with very short pulses.

Contribution

It introduces a Landau-Zener transfer matrix theory for Floquet states in pulse-driven quantum systems, showing its applicability to few-cycle pulses and quantum interference phenomena.

Findings

Good quantitative agreement with few-cycle pulse excitation probabilities

Floquet-state interpretation explains quantum path interference

Effective for pulses as short as 2 cycles

Abstract

We develop the Landau-Zener transfer matrix theory for the instantaneous Floquet states (IFSs) for quantum systems driven by strong pulse lasers. Applying this theory to the pulse excitation probability in two-level quantum systems, we show unexpectedly good quantitative agreements for few-cycle pulses. This approach enables us to qualitatively understand the probability's peculiar behaviors as quantum path interference between IFSs. We also study the pulse-width dependence, finding that this Floquet-state interpretation remains useful for shorter pulses down to 2-cycle ones in the present model. These results imply that the Floquet theory is meaningful in experimental few-cycle lasers if applied appropriately in the sense of IFSs.