Quantum key distribution at 1550 nm using a pulse heralded single photon source

Area of Science:

• Quantum Information Science
• Quantum Cryptography
• Photonics

Background:

• Quantum key distribution (QKD) offers secure communication based on quantum mechanics principles.
• Previous QKD experiments faced limitations in distance and source technology.
• Heralded single photon sources are crucial for practical QKD implementations.

Purpose of the Study:

• To demonstrate the feasibility of QKD over extended fiber optic links using a pulsed heralded single photon source.
• To evaluate the performance and security of the implemented QKD system.
• To establish a new distance record for QKD with this specific source type.

Main Methods:

• Utilized a pulsed heralded single photon source for quantum key generation.
• Transmitted quantum signals over 40 km of standard optical fiber.
• Measured the Quantum Bit Error Rate (QBER) to assess system performance and security.

Main Results:

• Successfully performed quantum key distribution over 40 km of fiber, a first for this source type.
• Achieved a QBER of 4.23%, indicating a high level of security.
• Demonstrated the robustness of the heralded single photon source in a real-world fiber environment.

Conclusions:

• Pulsed heralded single photon sources are viable for long-distance quantum key distribution.
• The achieved QBER confirms the system's security against unconditional attacks.
• This work paves the way for secure quantum communication networks over significant distances.