High-dimensional intracity quantum cryptography with structured photons

Quantum key distribution (QKD) promises information-theoretically secure communication and is already on the verge of commercialization. The next step will be to implement high-dimensional protocols in order to improve noise resistance and increase the data rate. Hitherto, no experimental verification of high-dimensional QKD in the singlephoton regime has been conducted outside of the laboratory. Here, we report the realization of such a single-photon QKD system in a turbulent free-space link of 0.3 km over the city of Ottawa, taking advantage of both the spin and orbital angular momentum photonic degrees of freedom. This combination of optical angular momenta allows us to create a 4-dimensional quantum state;…

• JH
  Johns Hopkins University
• UO
  University of Ottawa
• GO
  Government of Canada
• CF
  Canada Foundation for Innovation
• CR
  Canada Research Chairs
• CE
  Canada Excellence Research Chairs, Government of Canada
• CF
  Canada First Research Excellence Fund
• NS
  Natural Sciences and Engineering Research Council of Canada