Multiplexed processing of quantum information across an ultrawide optical bandwidth.

Area of Science:

• Quantum Information Science
• Optical Physics
• Quantum Communication

Background:

• Current quantum information protocols are limited by the narrow electronic bandwidth of measurement devices.
• This bandwidth limitation vastly underutilizes the broad optical bandwidth of quantum light sources.
• There is a need for methods to efficiently process quantum information across wider spectral ranges.

Purpose of the Study:

• To introduce a general framework for frequency-multiplexing of quantum channels.
• To develop methods for efficient quantum information processing across the full optical bandwidth.
• To demonstrate the application of these techniques in quantum key distribution and teleportation.

Main Methods:

• Utilized a broadband squeezed-light source.
• Employed spectral manipulation techniques.
• Implemented parametric homodyne detection for parallel processing and measurement.
• Developed frequency-multiplexing framework for quantum channels.

Main Results:

• Demonstrated multiplexed protocols for continuous-variable quantum key distribution (CV-QKD) and quantum teleportation.
• Experimentally realized multiplexed CV-QKD over 23 independent spectral channels.
• Successfully implemented eavesdropping detection in each spectral channel.
• Showcased parallel generation, processing, and measurement of quantum information.

Conclusions:

• The developed frequency-multiplexing techniques enable efficient, parallel quantum information processing across broad optical bandwidths.
• These methods significantly increase the potential throughput of quantum protocols by orders of magnitude.
• This work paves the way for massively parallel quantum processing and advanced quantum communication systems.