1. Robust entanglement distribution via telecom fibre assisted by an asynchronous counter-propagating laser light
- Author
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Masato Koashi, Rikizo Ikuta, Masahiro Yabuno, Koichiro Miyanishi, Hirotaka Terai, Shigehito Miki, Nobuyuki Imoto, Yoshiaki Tsujimoto, Taro Yamashita, and Takashi Yamamoto
- Subjects
Photon ,Optical fiber ,Computer Networks and Communications ,Phase (waves) ,FOS: Physical sciences ,Physics::Optics ,Quantum entanglement ,Interference (wave propagation) ,01 natural sciences ,Noise (electronics) ,lcsh:QA75.5-76.95 ,law.invention ,010309 optics ,Spontaneous parametric down-conversion ,law ,0103 physical sciences ,Computer Science (miscellaneous) ,Quantum information ,010306 general physics ,Physics ,Quantum Physics ,business.industry ,Statistical and Nonlinear Physics ,lcsh:QC1-999 ,Computational Theory and Mathematics ,lcsh:Electronic computers. Computer science ,Quantum Physics (quant-ph) ,Telecommunications ,business ,lcsh:Physics - 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., 8 pages, 5 figures
- Published
- 2020