Abstract
We describe the implementation of a quantum key distribution (QKD) system using a single-photon source, operating at night in open air. The single-photon source at the heart of the functional and reliable set-up relies on the pulsed excitation of a single nitrogen-vacancy colour centre in a diamond nanocrystal. We tested the effect of attenuation on the polarized encoded photons for inferring the longer distance performance of our system. For strong attenuation, the use of pure single-photon states gives measurable advantage over systems relying on weak attenuated laser pulses. The results are in good agreement with theoretical models developed to assess QKD security.
Highlights
Key distribution remains a central problem in cryptography, as encryption system security cannot exceed key security
We will show that in a realistic regime corresponding to high losses in the quantum transmission channel, our single photon quantum key distribution (QKD) setup has a measurable advantage over similar systems using weak coherent pulses (WCP)
Considering the ratio of the 60 ns detection timeslots compared to the 35 ns radiative lifetime of the nitrogen vacancy (NV) color center, 82% of the single photon source (SPS) photons are falling within the detection gate while only 32% of the dark counts are introduced in the key exchange process
Summary
Key distribution remains a central problem in cryptography, as encryption system security cannot exceed key security. If the error rate remains within acceptable bounds Alice and Bob can distill a secure secret key, perfectly unknown by Eve, using key reconciliation procedures This perfectly secure key can be used for data encryption. The use of true single photon source (SPS) presents an intrinsic advantage over WCPs’ schemes since it potentially permits greater per-bit extraction of secure information This advantage becomes significant for systems with high losses on the quantum transmission channel like envisioned satellite QKD [9]. We will show that in a realistic regime corresponding to high losses in the quantum transmission channel, our single photon QKD setup has a measurable advantage over similar systems using WCP
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