Rigorous calibration of homodyne detection efficiency for continuous-variable quantum key distribution.

Area of Science:

• Quantum Information Science
• Quantum Optics
• Secure Communication Technologies

Background:

• Accurate calibration of detection efficiency is crucial for secure continuous-variable quantum key distribution (CV-QKD).
• Existing methods may overlook factors contributing to detection inefficiency, potentially compromising security.
• Homodyne detection is a key component in CV-QKD systems.

Purpose of the Study:

• To propose and validate a rigorous calibration method for homodyne detection efficiency in CV-QKD.
• To establish a trusted, detection noise-free model for CV-QKD systems.
• To identify and mitigate security loopholes arising from inaccurate efficiency calibration.

Main Methods:

• Developed a calibration method integrating all factors affecting homodyne detection efficiency.
• Utilized actual homodyne detection measurements for calibration.
• Demonstrated the method using a balanced detector with a transimpedance amplifier.

Main Results:

• The proposed method correctly attributes transmittance from electronic noise to detection inefficiency.
• Overlooking the detector's integration factor leads to overestimated detection efficiency.
• Overestimated detection efficiency results in underestimated modulation variance and excess noise, creating security vulnerabilities.

Conclusions:

• The novel calibration method simplifies shot noise calibration while maintaining performance.
• Accurate calibration of detection efficiency is essential for robust CV-QKD security.
• This method provides a necessary approach for reliable detection efficiency calibration in CV-QKD.