Silicon photonic transceiver circuit for high-speed polarization-based discrete variable quantum key distribution

Area of Science:

• Quantum Information Science
• Integrated Photonics
• Quantum Cryptography

Background:

• Quantum key distribution (QKD) offers secure communication.
• Polarization-based QKD protocols require efficient state generation and detection.
• Integrated photonic circuits can miniaturize and enhance QKD systems.

Purpose of the Study:

• To demonstrate a novel silicon photonic transceiver circuit.
• To enable high-speed discrete variable quantum key distribution (DV-QKD).
• To utilize a common structure for both transmit and receive functions in a single device.

Main Methods:

• Design and fabrication of a silicon photonic transceiver.
• Characterization of the circuit's performance for quantum state generation and detection.
• Testing the device's compatibility with polarization-based quantum cryptographic protocols, specifically BB84.

Main Results:

• The transceiver successfully generates the four BB84 quantum states (TE, TM, 45°, 135° linear polarizations).
• Achieved polarization extinction ratios exceeding 30 dB.
• Demonstrated gigabit per second modulation speed.
• Confirmed capability to decode polarization bases differing by 90° with high extinction ratios.

Conclusions:

• The developed silicon photonic transceiver is suitable for high-speed, polarization-based quantum key distribution.
• The integrated design offers a compact and efficient solution for quantum communication systems.
• This technology advances the practical implementation of quantum cryptography.