Coherently opening a high-Q cavity

TL;DR

This paper introduces a framework for coherently opening and closing high-Q cavities using a mediating mode, enabling controlled release or feeding of quantum states with potential implementations in cavity QED systems.

Contribution

It presents a general theoretical model for effectively opening high-Q resonators via a mediating mode, with practical implementation strategies using atomic ensembles and three-level atoms.

Findings

Identifies the optimal traveling mode for quantum information retention.

Provides analytical figures of merit for system parameters.

Proposes feasible implementations with atomic ensembles and cavity QED.

Abstract

We propose a general framework to effectively `open' a high-Q resonator, that is, to release the quantum state initially prepared in it in the form of a traveling electromagnetic wave. This is achieved by employing a mediating mode that scatters coherently the radiation from the resonator into a one-dimensional continuum of modes such as a waveguide. The same mechanism may be used to `feed' a desired quantum field to an initially empty cavity. Switching between an `open' and `closed' resonator may then be obtained by controlling either the detuning of the scatterer or the amount of time it spends in the resonator. First, we introduce the model in its general form, identifying (i) the traveling mode that optimally retains the full quantum information of the resonator field and (ii) a suitable figure of merit that we study analytically in terms of the system parameters. Then, we discuss two feasible implementations based on ensembles of two-level atoms interacting with cavity fields. In addition, we discuss how to integrate traditional cavity QED in our proposal using three-level atoms.