Multiple-input multiple-output CV-MDI-QKD system for terahertz channels based on orthogonal time frequency space

Area of Science:

• Quantum Information Science
• Wireless Communication
• Terahertz Technology

Background:

• Continuous-variable measurement-device-independent quantum key distribution (CV-MDI-QKD) provides security against detector attacks by using untrusted devices.
• Terahertz (THz) communication faces challenges like time-varying and frequency-selective fading.

Purpose of the Study:

• To propose a novel multiple-input multiple-output (MIMO) CV-MDI-QKD system for THz channels.
• To enhance security and extend transmission distances in quantum key distribution.

Main Methods:

• Utilizing orthogonal time frequency space (OTFS) modulation for mapping information bits in the delay-Doppler domain.
• Employing MIMO beamforming to counteract free-space path loss in THz frequencies.
• Calculating the secret key rate under strict composable security, considering finite-size effects.

Main Results:

• The proposed system demonstrates increased secret key rates and longer secure transmission distances.
• Integration of OTFS and MIMO beamforming effectively mitigates multi-path and Doppler effects.
• The system maintains strong security against optimal collective Gaussian attacks.

Conclusions:

• The developed MIMO CV-MDI-QKD system offers a significant advancement for secure wireless communication in 5G and beyond.
• This technology enhances the robustness and range of quantum key distribution in challenging THz environments.
• The findings pave the way for more secure and efficient future wireless networks.