Qcrypt 2022: Poster25

Описание: MIMO Terahertz Continuous Variable Quantum Key Distribution



Authors
Neel Kanth Kundu (The Hong Kong University of Science and Technology); Soumya P. Dash (Indian Institute of Technology Bhubaneswar); Matthew R. McKay (The Hong Kong University of Science and Technology , University of Melbourne); Ranjan K. Mallik (Indian Institute of Technology Delhi)


Abstract
We propose a multiple-input multiple-output (MIMO) transmission scheme for a continuous-variable quantum key distribution (CVQKD) system operating at terahertz (THz) frequency. Motivated by classical MIMO communications, a transmit-receive beamforming scheme is proposed that converts the rank-r MIMO channel between Alice and Bob into r parallel lossy quantum channels. We also propose a practical channel estimation scheme for the THz MIMO CVQKD system which is necessary to realize transmit-receive beamforming between Alice and Bob. We characterize the input-output relation between Alice and Bob during the key generation phase, by incorporating the effects of additional noise terms arising due to the channel estimation error and detector noise. We also derive new expressions for the secret key rate (SKR) of the MIMO THz CVQKD system and analyze the effects of important system parameters on the SKR. Compared with existing single-antenna CVQKD schemes, we demonstrate that the MIMO QKD scheme leads to performance improvements by increasing the SKR and extending the transmission distance. Our simulation results show that multiple antennas are necessary to overcome the high free-space path loss at THz frequencies. Moreover, our theoretical results reveal that positive SKR can be achieved in the 10-30 THz frequency range at room temperature using the MIMO CVQKD scheme. Therefore, the MIMO THz CVQKD scheme can support both indoor and outdoor QKD applications in 6G wireless networks.


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