Retrieval of single photons from solid-state quantum transducers

TL;DR

This paper provides a theoretical analysis of the spectral properties and efficiency of solid-state quantum transducers used for converting photons across different frequencies, crucial for quantum network nodes.

Contribution

It derives an explicit expression linking stored and retrieved excitations, accounting for mode and phase mismatch, applicable across a wide frequency range.

Findings

Retrieval probability depends on optical depth.

Efficiency is maximized when retrieval is the time-reversal of storage.

The analysis applies to optical and microwave-to-optical transduction.

Abstract

Quantum networks using photonic channels require control of the interactions between the photons, carrying the information, and the elements comprising the nodes. In this work we theoretically analyse the spectral properties of an optical photon emitted by a solid-state quantum memory, which acts as a converter of a photon absorbed in another frequency range. We determine explicitly the expression connecting the stored and retrieved excitation taking into account possible mode and phase mismatch of the experimental setup. The expression we obtain describes the output field as a function of the input field for a transducer working over a wide range of frequencies, from optical-to-optical to microwave-to-optical. We apply this result to analyse the photon spectrum and the retrieval probability as a function of the optical depth for microwave-to-optical transduction. In the absence of losses, the efficiency of the solid-state quantum transducer is intrinsically determined by the capability of designing the retrieval process as the time-reversal of the storage dynamics.