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arXiv · 1903.06954

Genuine time-bin-encoded quantum key distribution over a turbulent depolarizing free-space channel

Jeongwan Jin·Jean-Philippe Bourgoin·Ramy Tannous·Sascha Agne·Christopher J. Pugh·Katanya B. Kuntz·Brendon L. Higgins·Thomas Jennewein
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Abstract

Despite its widespread use in fiber optics, encoding quantum information in photonic time-bin states is usually considered impractical for free-space quantum communication as turbulence-induced spatial distortion impedes the analysis of time-bin states at the receiver. Here, we demonstrate quantum key distribution using time-bin photonic states distorted by turbulence and depolarization during free-space transmission. Utilizing a novel analyzer apparatus, we observe stable quantum bit error ratios of 5.32 %, suitable for generating secure keys, despite significant wavefront distortions and polarization fluctuations across a 1.2 km channel. This shows the viability of time-bin quantum communication over long-distance free-space channels, which will simplify direct fiber/free-space interfaces and enable new approaches for practical free-space quantum communication over multi-mode, turbulent, or depolarizing channels.

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Jeongwan Jin, Jean-Philippe Bourgoin, Ramy Tannous, Sascha Agne, Christopher J. Pugh, Katanya B. Kuntz, Brendon L. Higgins, Thomas Jennewein. 2019-03-16. Genuine time-bin-encoded quantum key distribution over a turbulent depolarizing free-space channel. https://doi.org/10.1364/oe.27.037214

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