Provable Optimality of the Square-Tooth Atomic Frequency Comb Quantum Memory

Fuente: arXiv
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Auteurs principaux: Zang, Allen, Suchara, Martin, Zhong, Tian
Format: Preprint
Publié: 2024
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author Zang, Allen
Suchara, Martin
Zhong, Tian
author_facet Zang, Allen
Suchara, Martin
Zhong, Tian
contents Atomic frequency comb (AFC) quantum memories are a promising technology for quantum repeater networks because they enable multi-mode, long-time, and high-fidelity storage of photons with on-demand retrieval. The optimization of the retrieval efficiency of an AFC memory is important because it strongly impacts the entanglement distribution rate in quantum networks. Despite initial theoretical analyses and recent experimental demonstrations, a rigorous proof of the universally optimal configuration for the highest AFC retrieval efficiency has not been presented. In this paper we present a simple analytical proof which shows that the optimized square tooth offers the highest retrieval efficiency among all tooth shapes, under the physical constraint of finite optical depth of an atomic ensemble. The optimality still holds when the non-zero background absorption and the finite optical linewidth of atoms are considered. We further compare square, Lorentzian and Gaussian tooth shapes to reinforce the practical advantage of the square-tooth AFC in retrieval efficiency. Our proof lays rigorous foundation for the recipe of creating optimal AFC under realistic experimental conditions.
format Preprint
id arxiv_https___arxiv_org_abs_2406_01769
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Provable Optimality of the Square-Tooth Atomic Frequency Comb Quantum Memory
Zang, Allen
Suchara, Martin
Zhong, Tian
Quantum Physics
Atomic frequency comb (AFC) quantum memories are a promising technology for quantum repeater networks because they enable multi-mode, long-time, and high-fidelity storage of photons with on-demand retrieval. The optimization of the retrieval efficiency of an AFC memory is important because it strongly impacts the entanglement distribution rate in quantum networks. Despite initial theoretical analyses and recent experimental demonstrations, a rigorous proof of the universally optimal configuration for the highest AFC retrieval efficiency has not been presented. In this paper we present a simple analytical proof which shows that the optimized square tooth offers the highest retrieval efficiency among all tooth shapes, under the physical constraint of finite optical depth of an atomic ensemble. The optimality still holds when the non-zero background absorption and the finite optical linewidth of atoms are considered. We further compare square, Lorentzian and Gaussian tooth shapes to reinforce the practical advantage of the square-tooth AFC in retrieval efficiency. Our proof lays rigorous foundation for the recipe of creating optimal AFC under realistic experimental conditions.
title Provable Optimality of the Square-Tooth Atomic Frequency Comb Quantum Memory
topic Quantum Physics
url https://arxiv.org/abs/2406.01769