Digitizing ultrafast adiabatic passage with a pulse train

TL;DR

This paper introduces a method to digitize rapid adiabatic passage using a train of ultrafast pulses, enabling high-fidelity population control with fewer pulses and exploiting frequency comb sidebands for advanced state preparation.

Contribution

It develops analytic conditions for pulse train parameters to replicate continuous adiabatic dynamics and demonstrates applications in resonant excitation and superposition state preparation.

Findings

High fidelity reproduction with few subpulses within perturbative regime

Complex dynamics require more subpulses for accuracy

Frequency comb sidebands enable resonant excitation and superposition states

Abstract

We present a digitized implementation of rapid adiabatic passage based on a train of weak, frequency-varying ultrafast pulses. Analytic conditions on the subpulse Rabi frequencies and detunings are derived to reproduce the continuous-time population dynamics of a conventional long-pulse excitation. We find that the reproduced dynamics achieves high fidelity even for pulse trains with a small number of subpulses, provided that each subpulse remains within the perturbative regime. The subpulses act as discrete samples of the underlying continuous evolution; consequently, more complex population dynamics, characterized by multiple oscillations prior to the onset of adiabaticity, require a larger number of subpulses for accurate reproduction. In addition, we demonstrate how the sidebands of a frequency comb can be exploited for resonant excitation at large carrier detuning and for the precise preparation of superposition states.