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arXiv · 2608.18666

Experimental zero-added-loss multiplexing Bell-pair source for long-haul quantum networks

Yoshiaki Tsujimoto·Daiki Ichii·Rikizo Ikuta·Mikio Fujiwara·Masahiro Takeoka·Go Kato·Kentaro Wakui
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Abstract

Boosting the communication rate of quantum networks is a central challenge in quantum information science. Recently, an efficient entanglement distribution scheme employing quasi-deterministic Bell-pair sources based on time-frequency multiplexing, referred to as zero-added-loss multiplexing~(ZALM), has been proposed. Its implementation, however, requires high-fidelity entanglement swapping across densely multiplexed time-frequency modes, which has remained an experimental challenge. Here we demonstrate entanglement swapping across 16 parallel frequency modes with a high average fidelity of 93.9$\pm$\SI{1.4}{\%}. Notably, polarization-entangled photon pairs in each frequency mode are spectrally single-mode using only off-the-shelf 50-GHz dense wavelength-division multiplexing~(DWDM) filters, eliminating the need for additional narrowband filtering. Furthermore, in order to fully exploit the temporal degree of freedom, the pump pulse is operated with a repetition frequency of \SI{3.0}{GHz}. By combining the frequency and time multiplexing, the total swapping rate reaches 5.38$\pm$0.17\,\si{pairs\,s^{-1}}, which corresponds to the ZALM Bell-pair rate of \SI{8.2e2}{pairs\,s^{-1}}. Our results establish the key experimental capabilities required for ZALM and demonstrate a scalable route toward practical high-rate quantum repeaters and long-haul quantum networks.

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Yoshiaki Tsujimoto, Daiki Ichii, Rikizo Ikuta, Mikio Fujiwara, Masahiro Takeoka, Go Kato, Kentaro Wakui. 2026-08-19. Experimental zero-added-loss multiplexing Bell-pair source for long-haul quantum networks. https://arxiv.org/abs/2608.18666

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