Complete population transfer in a three-state quantum system by a train of pairs of coincident pulses

TL;DR

This paper introduces a method using a train of resonant, coincident pulse pairs to achieve complete population transfer in a three-state quantum system, effectively bridging $ ext{π}$-pulses and STIRAP.

Contribution

A new analytic approach for population transfer using pulse trains with minimized intermediate state population, connecting $ ext{π}$-pulses and STIRAP techniques.

Findings

Population transfer efficiency increases with the number of pulse pairs.

Maximum transient population of the middle state is minimized by specific pulse amplitude ratios.

The technique works effectively even with a small number of pulse pairs.

Abstract

A technique for complete population transfer between the two end states $\ket{1}$ and $\ket{3}$ of a three-state quantum system with a train of $N$ pairs of resonant and coincident pump and Stokes pulses is introduced. A simple analytic formula is derived for the ratios of the pulse amplitudes in each pair for which the maximum transient population $P_2(t)$ of the middle state $\ket{2}$ is minimized, $P_2^{\max}=\sin^2(\pi/4N)$. It is remarkable that, even though the pulses are on exact resonance, $P_2(t)$ is damped to negligibly small values even for a small number of pulse pairs. The population dynamics resembles generalized $\pi$-pulses for small $N$ and stimulated Raman adiabatic passage for large $N$ and therefore this technique can be viewed as a bridge between these well-known techniques.