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arXiv:2510.12556

Optimization of the time-multiplexed SPDC source at 900-950 nm range

V. O. Gotovtsev, I. V. Dyakonov, O. V. Borzenkova, K. V. Taratorin, T. B. Dugarnimaev, Alexander A. Korneev, S. P. Kulik, S. S. Straupe

Published Oct 14, 2025• 0 citations
arXivHTMLPDF

Abstract

In the field of quantum technology, single photons have emerged as a pivotal resource, prompting the development of heralded single photon sources (HSPS) with enhanced generation probability. The majority of such sources are based on spontaneous parametric down-conversion (SPDC), but they exhibit a low single photon generation probability. The multiplexing principle (arXiv:quant-ph/0205103) has been proposed as a solution to this problem. This paper presents a demonstration of a time-multiplexed HSPS based on the SPDC process, including accurate calculations and modeling of key source characteristics, specifically purity and heralding efficiency. Furthermore, the paper provides an analysis and approximation of the probability of a single photon post-application of time multiplexing.

DOI
10.48550/arxiv.2510.12556

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•Dec 7, 2016•0 citations
In the field of quantum technology, single photons have emerged as a pivotal resource, prompting the development of heralded single photon sources (HSPS) with enhanced generation probability. The majority of such sources are based on spontaneous parametric down-conversion (SPDC), but they exhibit a low single photon generation probability. The multiplexing principle (arXiv:quant-ph/0205103) has been proposed as a solution to this problem. This paper presents a demonstration of a time-multiplexed HSPS based on the SPDC process, including accurate calculations and modeling of key source characteristics, specifically purity and heralding efficiency. Furthermore, the paper provides an analysis and approximation of the probability of a single photon post-application of time multiplexing.
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High-rate entanglement generation is essential for the realization of practical quantum repeaters. To this end, frequency multiplexing of the photons employed is an effective approach. In particular, schemes using cavity-enhanced spontaneous parametric down-conversion (cSPDC) as a photon-pair source have been proposed. In this study, toward a theoretical performance evaluation of frequency-multiplexed quantum repeaters based on cSPDC, we derive an approximate expression for the quantum state of the frequency-multiplexed photons, where each frequency mode is treated as an independent two-mode squeezed vacuum (TMSV) state. Using this expression, we calculate the heralding probability and fidelity of entanglement generation for several cases in a single-photon interference scheme using frequency multiplexing with cSPDC. Our results demonstrate that by multiplexing approximately 100 modes, the heralding probability improves to approximately 98% for an elementary link distance LEL=25kmL_\mathrm{EL}=25 \mathrm{km}LEL​=25km, even in scenarios where the fidelity exceeds 0.9 across all modes. Furthermore, for LEL=100kmL_\mathrm{EL}=100 \mathrm{km}LEL​=100km, we show that the heralding probability, which was approximately 0.7% in the single-mode case, increases to about 38% under the condition that the fidelity remains 0.9 or higher. These analytical results demonstrate the effectiveness of employing cSPDC as a photon-pair source for quantum repeaters.
Heralded single photon sources (HSPS) using spontaneous parametric down conversion (SPDC) are widely used in photonic quantum information. However, the excess-photon pair generation in SPDC process is a problem, which results in the events where more than two photons exist in a pulse. Such excess photons degrade the visibility (V) of two-photon Hong-Ou-Mandel interference, and are one of the main error causes in the advanced linear optics photonic circuits. Recently, we have developed a novel HSPS which combines two methods to suppress such excess photon numbers. The first method (A) is to use multiple SPDC sources in one HSPS, where upon the detection of the idler photon from one of the source, the corresponding signal photon is output. The second method (B) is to use cascaded detectors to monitor the photon-pair number generated from the source, where the detector distinguish the single-pair generation from multi-pair generation and thus the excess-photon generation can be suppressed. In this presentation, we report the theoretical calculations how such a source can improve the visibility for a two photon interference. For example, when the average number of pairs from SPDC in a pulse is 0.1, and the detection efficiency is 70%, V= 83.2% for a conventional HSPS. V is improved to 90.3%, 87.1% and 92.7% by using method A, B and our hybrid approach, respectively.