# Stimulated Raman adiabatic passage-like protocols for amplitude transfer generalize to many bipartite graphs

## TL;DR

This paper generalizes adiabatic quantum amplitude transfer protocols, like STIRAP and CTAP, to a broad class of bipartite graphs, demonstrating their effectiveness and stability for quantum communication in complex networks.

## Contribution

It proves that adiabatic transfer protocols work on many bipartite graphs with perfect matchings, extending previous results beyond simple structures.

## Key findings

- Adiabatic transfer is possible on graphs with perfect matchings after removing sender or receiver.
- Protocols inherit stability properties of STIRAP/CTAP, applicable to multiple senders and receivers.
- Numerical tests show accurate transfer on tree leaves, especially with straddling.

## Abstract

Adiabatic passage techniques, used to drive a system from one quantum state into another, find widespread application in physics and chemistry. We focus on techniques to spatially transport a quantum amplitude over a strongly coupled system, such as STImulated Raman Adiabatic Passage (STIRAP) and Coherent Tunnelling by Adiabatic Passage (CTAP). Previous results were shown to work on certain graphs, such as linear chains, square and triangular lattices, and branched chains. We prove that similar protocols work much more generally, in a large class of (semi-)bipartite graphs. In particular, under random couplings, adiabatic transfer is possible on graphs that admit a perfect matching both when the sender is removed and when the receiver is removed. Many of the favorable stability properties of STIRAP/CTAP are inherited, and our results readily apply to transfer between multiple potential senders and receivers. We numerically test transfer between the leaves of a tree, and find surprisingly accurate transfer, especially when straddling is used. Our results may find applications in short-distance communication between multiple quantum computers, and open up a new question in graph theory about the spectral gap around the value 0.