Optimal storage of a single photon by a single intra-cavity atom

TL;DR

This paper provides a theoretical analysis of optimizing single-photon storage efficiency in a cavity-atom system, including pulse shaping and loss mitigation, supported by numerical simulations aligned with experimental parameters.

Contribution

It introduces a numerical approach to determine maximal storage efficiency and optimal laser pulse shapes, extending beyond input-output theory limitations.

Findings

Maximal storage efficiency considering decay and losses

Optimal laser pulse shapes for efficiency

Shortest storable photon pulse length

Abstract

We theoretically analyse the efficiency of a quantum memory for single photons. The photons propagate along a transmission line and impinge on one of the mirrors of a high-finesse cavity. The quantum memory is constituted by a single atom within the optical resonator. Photon storage is realised by the controlled transfer of the photonic excitation into a metastable state of the atom and occurs via a Raman transition with a suitably tailored laser pulse, which drives the atom. Our study is supported by numerical simulations, in which we include the modes of the transmission line and we use the experimental parameters of existing experimental setups. It reproduces the results derived using input-output theory in the corresponding regime and can be extended to compute dynamics where the input-output formalism cannot be straightforwardly applied. Our analysis determines the maximal storage efficiency, namely, the maximal probability to store the photon in a stable atomic excitation, in the presence of spontaneous decay and cavity parasitic losses. It further delivers the form of the laser pulse that achieves the maximal efficiency by partially compensating parasitic losses. We numerically assess the conditions under which storage based on adiabatic dynamics is preferable to non-adiabatic pulses. Moreover, we systematically determine the shortest photon pulse that can be efficiently stored as a function of the system parameters.