Photonics Research, Volume. 9, Issue 12, 2351(2021)
Frequency-multiplexed entanglement for continuous-variable quantum key distribution
Fig. 1. Bright colors show a sketch of a CV QKD testbed for the study of the multimode entangled source at the side of the sender, Alice, with cross-talk coupling between the frequency modes in both of the two beams, leaving the source. The entangled source is based on eight pairs of modes, where only four of them are shown for clarity. We consider a scenario where half of the modes (below the central frequency) are locally measured by Alice and another half (above the central frequency) transmitted to a remote trusted party Bob (trusted devices are given in dashed blocks). Both multimode beams are detected by homodyne detectors and processed to optimally eliminate the cross talk and improve the secret key rate. The data processing corresponds to a local physical multimode symplectic transformation and was optimized to achieve higher key rate between the trusted parties. The trusted parties then can use authenticated classical channel to perform post-processing by correcting their errors and amplifying the data privacy in order to obtain quantum-secure key as the result (this part of the protocol was modeled numerically so is illustrated in pale colors).
Fig. 2. Experimental setup for generation of frequency-multiplexed multimode entangled light and its measurement with mode-discriminating homodyne detection. The generated multimode light
Fig. 3. Left panel: estimated key rate (in terms of bits per multimode channel use) of CV QKD based on the frequency-multiplexed entangled source in Fig.
Fig. 4. Key rate of CV QKD versus channel transmittance
Fig. 5. Visualization of covariance matrices in
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Olena Kovalenko, Young-Sik Ra, Yin Cai, Vladyslav C. Usenko, Claude Fabre, Nicolas Treps, Radim Filip, "Frequency-multiplexed entanglement for continuous-variable quantum key distribution," Photonics Res. 9, 2351 (2021)
Category: Quantum Optics
Received: Jun. 24, 2021
Accepted: Oct. 5, 2021
Published Online: Nov. 5, 2021
The Author Email: Olena Kovalenko (kovalenko@optics.upol.cz)