Experiments on long wavelength (1550 nm) "plug and play" quantum cryptography systems

Area of Science:

• Quantum Information Science
• Quantum Cryptography
• Photonics

Background:

• Quantum cryptography offers enhanced security through quantum mechanics principles.
• Secure communication systems require robust single-photon detection at specific wavelengths.
• Interferometric setups are crucial for implementing quantum key distribution protocols.

Purpose of the Study:

• To demonstrate a functional interferometric quantum cryptographic system.
• To evaluate the system's performance using specific single-photon receivers.
• To determine the maximum transmission distance for secure quantum communication.

Main Methods:

• An interferometric quantum cryptographic system was designed and implemented.
• Gated Indium Gallium Arsenide (InGaAs) Avalanche Photo Diodes were used as single-photon receivers.
• The system operated at a 1550nm wavelength, suitable for fiber optic transmission.
• System performance was tested for secure data transmission over varying distances.

Main Results:

• The interferometric quantum cryptographic system was successfully demonstrated.
• The system achieved secure quantum communication up to a transmission distance of 40 km.
• The use of gated InGaAs Avalanche Photo Diodes proved effective for single-photon detection at 1550nm.

Conclusions:

• The feasibility of an interferometric quantum cryptographic system using gated InGaAs Avalanche Photo Diodes for long-distance secure communication is confirmed.
• The 1550nm wavelength and specific detectors enable robust quantum key distribution over 40 km.
• This work contributes to the advancement of practical quantum communication networks.