Researchers at NIST have developed a new quantum key distribution (QKD) system that can transmit secure keys at over half a million bits per second over 10 km of optical fiber. The system uses a new detector system based on a silicon avalanche photo diode (Si-APD) that achieves dramatically lower noise levels than similar systems. This allows the system to perform a theoretically unbreakable “one-time pad” encryption, transmission and decryption of a video signal in real-time.
The new system is compatible with existing fiber-optic telecom networks that transmit at wavelengths of either 1550 or 1310 nanometers. The NIST group designed a subsystem to “up-convert” single photons from a transmission wavelength of 1310 nm to 710 nm for high-efficiency detection. The QKD system incorporates this up-conversion technique, which allows for high speed, high efficiency, low noise and convenient operation.
The system’s advantages include high speed, high efficiency, low noise and convenience of operation. The fact that it uses a 1310 nm transmission wavelength somewhat limits the propagation distance but adds the advantage that the parallel “classical-quantum” communication, which is needed for a full QKD system, can be realized in a single fiber without significant interference.
Source: https://www.nist.gov/news-events/news/2007/06/new-quantum-key-system-combines-speed-distance
Keywords: Key distribution, Quantum key distribution, Photon detector, Avalanche photo diode, Up-conversion technique
