Chip-scale transmitter module for real-time continuous-variable QKD.

Area of Science:

• Quantum Information Science
• Optical Engineering
• Secure Communications

Background:

• Continuous-variable quantum key distribution (CV-QKD) offers secure communication channels.
• Current CV-QKD systems are hindered by large, discrete optical hardware, limiting scalability.
• Advancements are needed to integrate CV-QKD into existing telecom infrastructure.

Purpose of the Study:

• To demonstrate a real-time CV-QKD system using a chip-scale hybrid transmitter.
• To overcome the scaling bottleneck caused by bulky optical hardware.
• To enable cost-effective quantum networks through miniaturization and real-time operation.

Main Methods:

• Developed a chip-scale hybrid transmitter integrating a micro-optic external-cavity laser and a monolithic photonic integrated IQ modulator.
• Implemented a real-time operational framework for CV-QKD.
• Utilized commercial telecom components for transmitter construction.

Main Results:

• Achieved secure secret-key generation over 102 km of optical fiber.
• Reduced the optical hardware volume by 95% compared to discrete-component systems.
• Demonstrated real-time CV-QKD operation, eliminating offline post-processing delays.

Conclusions:

• The chip-scale hybrid transmitter significantly advances CV-QKD technology.
• This miniaturized, real-time system addresses key scaling limitations for practical quantum networks.
• The work paves the way for field-deployable and cost-effective quantum communication solutions.