Non-Hermitian shortcut to stimulated Raman adiabatic passage

TL;DR

This paper introduces a non-Hermitian approach to STIRAP that enhances speed and fidelity by canceling nonadiabatic couplings with balanced gain/loss terms, and suggests a practical optical waveguide implementation.

Contribution

It presents a novel non-Hermitian generalization of STIRAP that acts as a shortcut to adiabaticity, improving performance and providing a feasible physical realization.

Findings

Imaginary terms are time independent in Gaussian-shaped pulse schemes

Enhanced speed and fidelity in adiabatic passage achieved

Proposed implementation in optical waveguides

Abstract

We propose a non-Hermitian generalization of stimulated Raman adiabatic passage (STIRAP), which allows one to increase speed and fidelity of the adiabatic passage. This is done by adding balanced imaginary (gain/loss) terms in the diagonal (bare energy) terms of the Hamiltonian and choosing them such that they cancel exactly the nonadiabatic couplings, providing in this way an effective shortcut to adiabaticity. Remarkably, for a STIRAP using delayed Gaussian-shaped pulses in the counter-intuitive scheme the imaginary terms of the Hamiltonian turn out to be time independent. A possible physical realization of non-Hermitian STIRAP, based on light transfer in three evanescently-coupled optical waveguides, is proposed.