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1.5-µm Narrow-band Two-photon Source for Long-distance Quantum Communication

Kazuya Niizeki, Kohei Ikeda, Mingyang Zheng, Xiu-Ping Xie, Kotaro Okamura, Nobuyuki Takei, Naoto Namekata, Shuichiro Inoue, Hideo Kosaka, Tomoyuki Horikiri

Published Jan 1, 2018• 0 citations
Publisher

Abstract

We demonstrate a narrow-band telecom two-photon source for long-distance quantum communication. The second-order cross-correlation function reveals narrow linewidth of 2.4 MHz and the highest spectral brightness of3.94 × 105 pairs/(s.MHz.mW).
DOI
10.1364/cleopr.2018.th4j.6

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We demonstrate two-photon sources for long-distance quantum communication. The highest spectral brightness 3.94×105pairs/(sMHzmW)3.94\times 10^{5}\mathrm{pairs}/(\mathrm{s} \mathrm{ MHz} \mathrm{mW})3.94×105pairs/(sMHzmW) , the narrowest linewidth in telecom of 1.06 MHz and entanglement fidelity of91.8% are shown. © 2019 The Author(s)
Quantum computing and quantum communication, have been greatly developed in recent years and expected to contribute to quantum internet technologies, including cloud quantum computing and unconditionally secure communication. However, long-distance quantum communication is challenging mainly because of optical fiber losses; quantum repeaters are indispensable for fiber-based transmission because unknown quantum states cannot be amplified with certainty. In this study, we demonstrate a versatile entanglement source in the telecom band for fiber-based quantum internet, which has a narrow linewidth of sub-MHz range, entanglement fidelity of more than 95%, and Bell-state generation even with frequency multimode. Furthermore, after a total distribution length of 20-km in fiber, two-photon correlation is observed with an easily identifiable normalized correlation coefficient, despite the limited bandwidth of the wavelength converter. The presented implementation promises an efficient method for entanglement distribution that is compatible with quantum memory and frequency-multiplexed long-distance quantum communication applications. Quantum technologies have seen a remarkable development in recent years and are expected to contribute to quantum internet technologies. The authors present an experimental implementation over commercial telecom fibres of a two-photon comb source for quantum communications with long coherence times and narrow bandwidth, which is used in a 20 km distribution experiment to show the presence of remote two-photon correlations.
This paper reports a novel single mode source of narrow-band entangled photon pairs at telecom wavelengths under continuous wave excitation, based on parametric down conversion. For only 7 mW of pump power it has a created spectral radiance of 0.08 pairs per coherence length and a bandwidth of 10 pm (1.2 GHz). The effectively emitted spectral brightness reaches 3.9*10^5 pairs /(s pm). Furthermore, when combined with low jitter single photon detectors, such sources allow for the implementation of quantum communication protocols without any active synchronization or path length stabilization. A HOM-Dip with photons from two autonomous CW sources has been realized demonstrating the setup's stability and performance.
This paper reports a novel single mode source of narrow-band entangled photon pairs at telecom wavelengths under continuous wave (CW) excitation, based on parametric down conversion. For only 7 mW of pump power it has a created spectral radiance of 0.08 pairs per coherence length and a bandwidth of 10 pm (1.2 GHz). The effectively emitted spectral brightness reaches 3.9 × 10 5 pairs s −1 pm −1 . Furthermore, when combined with low jitter single photon detectors, such sources allow for the implementation of quantum communication protocols without any active synchronization or path length stabilization. A Hong–Ou–Mandel (HOM)-dip with photons from two autonomous CW sources has been realized demonstrating the setup's stability and performance.