Limits of single-photon storage in a single $\Lambda$-type atom

TL;DR

This paper explores the fundamental limits of single-photon storage in a single Λ-type atom, analyzing how control fields and waveguide properties affect efficiency and speed, with implications for quantum information processing.

Contribution

It provides a theoretical analysis of the trade-offs and limits in single-photon storage, including the effects of waveguide type and quantum statistics, advancing understanding of quantum memory constraints.

Findings

Storage efficiency upper limit of 50% in regular waveguides

Control fields can accelerate storage without significant efficiency loss

Perfect storage possible with chiral waveguides or Sagnac interferometry

Abstract

We theoretically investigate the limits of single-photon storage in a single $\Lambda$-type atom, specifically the trade-off between storage efficiency and storage speed. We show that a control field can accelerate the storage process without degrading efficiency too much. However, the storage speed is ultimately limited by the total decay rate of the involved excited state. For a single-photon pulse propagating in a regular one-dimensional waveguide, the storage efficiency has an upper limit of $50 \%$. Perfect single-photon storage can be achieved by using a chiral waveguide or the Sagnac interferometry. By comparing the storage efficiencies of Fock-state and coherent-state pulses, we reveal the influence of quantum statistics of light on photon storage at the single-photon level.