NIST photon number resolving detectors contribute to quantum key distribution.

In collaboration with a team of researchers at Los Alamos National Labs (LANL), researchers at NIST have, for the first time, combined the fiber-based quantum key distribution system demonstrated by the LANL team with the photon number resolving detectors developed by NIST. The fiber-based system used light from a weak coherent laser pulse at 1310 nm to transmit key material and attenuators between the transmitter and receiver to simulate fiber losses over long distances.

As part of the Defense Advanced Research Projects Agency's Quantum Information Science and Technology program, NIST researchers have designed and built a prototype single photon detection system that has demonstrated the ability to count the number of photons in a short pulse of light with no dark counts. The detectors are superconducting transition-edge sensors (TES), optimized for the detection of optical and telecommunication wavelength photons. Each photon or group of photons absorbed by the TES devices produces a signal that is a short current pulse with a relatively fast rise time, <1 [micro]s, and a decay time of 20 [micro]s.

With conventional detectors, the dark count rate is responsible for an increased error rate and, consequently, a loss of security over long distances. Because of the extremely low dark count rate with a TES detector, it should be possible to securely transmit key material over longer distances ([approximately equal to]100 km).

CONTACT: Sae Woo Nam, [phone]; [e-mail].