Adaptable transmitter for discrete and continuous variable quantum key distribution

Area of Science:

• Quantum Information Science
• Quantum Communication
• Cryptography

Background:

• Quantum Key Distribution (QKD) offers secure communication by leveraging quantum mechanics principles.
• Implementing both discrete variable (DV-QKD) and continuous variable (CV-QKD) protocols typically requires distinct hardware setups.
• The need for flexible and efficient QKD systems is growing, especially for adaptable optical network infrastructures.

Purpose of the Study:

• To present a novel, versatile transmitter capable of executing both DV-QKD and CV-QKD protocols.
• To demonstrate the transmitter's performance in real-world quantum channel scenarios.
• To highlight the transmitter's suitability for re-configurable optical networks.

Main Methods:

• Development of a single, versatile transmitter for quantum key distribution.
• Implementation of a time-bin encoded BB84 DV-QKD protocol over a 47 km optical fiber channel.
• Implementation of a Gaussian-modulated continuous-variable (GG02) CV-QKD protocol with a true local oscillator over a 10.5 km optical fiber channel.

Main Results:

• Achieved a secret key rate of 4.1 kbps for the DV-QKD protocol.
• Achieved a secret key rate of 1 Mbps for the CV-QKD protocol.
• Demonstrated the transmitter's capability to switch between DV- and CV-QKD protocols.

Conclusions:

• The presented versatile transmitter successfully supports both DV-QKD and CV-QKD protocols.
• The system demonstrates practical secret key generation over substantial fiber optic links.
• This versatile transmitter is well-suited for re-configurable optical networks, allowing protocol optimization based on link characteristics.