# Coherent trapping in small quantum networks

## TL;DR

This paper investigates coherent population trapping in a three-node quantum network, exploring its control, robustness, and implications for quantum transport and protocols.

## Contribution

It generalizes known trapping phenomena to a three-node network, analyzes environmental effects, and proposes control protocols for quantum transport.

## Key findings

- Coherent trapping occurs in a three-node network, extending Lambda network results.
- Transport signatures reveal detrapping mechanisms controllable externally.
- Adiabatic modulation enables robust population transfer, resistant to non-adiabatic effects.

## Abstract

We consider a three-node fully connected network (Delta network) showing that a coherent population trapping phenomenon occurs, generalizing results for the Lambda network known to support a dark state. Transport in such structures provides signatures of detrapping, which can be triggered by external controls. In the presence of an environment it turns out to be sensitive to its Markovianity. Adiabatic modulation of the system's parameters may yield coherent population transfer, analogous to the stimulated Raman adiabatic passage phenomenon. Robustness of this protocol against non-adiabatic transitions is studied. Coherent nanostructures where these phenomena are relevant for quantum transport and quantum protocols are suggested.