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arXiv · 1910.11520

Robust entanglement distribution via telecom fibre assisted by an asynchronous counter-propagating laser light

Koichiro Miyanishi·Yoshiaki Tsujimoto·Rikizo Ikuta·Shigehito Miki·Masahiro Yabuno·Taro Yamashita·Hirotaka Terai·Takashi Yamamoto·Masato Koashi·Nobuyuki Imoto
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Abstract

Distributing entangled photon pairs over noisy channels is an important task for various quantum information protocols. Encoding an entangled state in a decoherence-free subspace (DFS) formed by multiple photons is a promising way to circumvent the phase fluctuations and polarization rotations in optical fibres. Recently, it has been shown that the use of a counter-propagating coherent light as an ancillary photon enables us to faithfully distribute entangled photon with success probability proportional to the transmittance of the optical fibres. Several proof-of-principle experiments have been demonstrated, in which entangled photon pairs from a sender side and the ancillary photon from a receiver side originate from the same laser source. In addition, bulk optics have been used to mimic the noises in optical fibres. Here, we demonstrate a DFS-based entanglement distribution over 1km-optical fibre using DFS formed by using fully independent light sources at the telecom band. In the experiment, we utilize an interference between asynchronous photons from cw-pumped spontaneous parametric down conversion (SPDC) and mode-locked coherent light pulse. After performing spectral and temporal filtering, the SPDC photons and light pulse are spectrally indistinguishable. This property allows us to observe high-visibility interference without performing active synchronization between fully independent sources.

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Koichiro Miyanishi, Yoshiaki Tsujimoto, Rikizo Ikuta, Shigehito Miki, Masahiro Yabuno, Taro Yamashita, Hirotaka Terai, Takashi Yamamoto, Masato Koashi, Nobuyuki Imoto. 2019-10-25. Robust entanglement distribution via telecom fibre assisted by an asynchronous counter-propagating laser light. https://arxiv.org/abs/1910.11520

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