Highly Efficient and Broadband Optical Delay Line towards a Quantum Memory

Fuente: arXiv
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Main Authors: Guo, Yu, Banerji, Anindya, Chin, Jia Boon, Chowdhury, Arya, Ling, Alexander
Format: Preprint
Published: 2025
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author Guo, Yu
Banerji, Anindya
Chin, Jia Boon
Chowdhury, Arya
Ling, Alexander
author_facet Guo, Yu
Banerji, Anindya
Chin, Jia Boon
Chowdhury, Arya
Ling, Alexander
contents We demonstrate a high-efficiency, free space optical delay line utilizing a nested multipass cell architecture. This design supports extended optical paths with low loss, aided by custom broadband dielectric coating that provides high reflectivity across a wide spectral bandwidth. The cell is characterized using polarization-entangled photon pairs, with signal photons routed through the delay line and idler photons used as timing reference. Quantum state tomography performed on the entangled pair reveals entanglement preservation with a fidelity of $99.6(9)\%$ following a single-transit delay of up to $687$~ns, accompanied by a photon retrieval efficiency of $95.390(5)%$. The delay is controllable and can be set between $1.8$~ns to $687$~ns in $\sim12.6$~ns increments. The longest delay and wide spectral bandwidth result in a time-bandwidth product of $3.87\times 10^7$. These results position this delay line as a strong candidate for all-optical quantum memories and synchronization modules for scalable quantum networks.
format Preprint
id arxiv_https___arxiv_org_abs_2509_02096
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Highly Efficient and Broadband Optical Delay Line towards a Quantum Memory
Guo, Yu
Banerji, Anindya
Chin, Jia Boon
Chowdhury, Arya
Ling, Alexander
Quantum Physics
Optics
We demonstrate a high-efficiency, free space optical delay line utilizing a nested multipass cell architecture. This design supports extended optical paths with low loss, aided by custom broadband dielectric coating that provides high reflectivity across a wide spectral bandwidth. The cell is characterized using polarization-entangled photon pairs, with signal photons routed through the delay line and idler photons used as timing reference. Quantum state tomography performed on the entangled pair reveals entanglement preservation with a fidelity of $99.6(9)\%$ following a single-transit delay of up to $687$~ns, accompanied by a photon retrieval efficiency of $95.390(5)%$. The delay is controllable and can be set between $1.8$~ns to $687$~ns in $\sim12.6$~ns increments. The longest delay and wide spectral bandwidth result in a time-bandwidth product of $3.87\times 10^7$. These results position this delay line as a strong candidate for all-optical quantum memories and synchronization modules for scalable quantum networks.
title Highly Efficient and Broadband Optical Delay Line towards a Quantum Memory
topic Quantum Physics
Optics
url https://arxiv.org/abs/2509.02096