Differential-phase-shift quantum key distribution experiment with a planar light-wave circuit Mach-Zehnder interferometer

Opt Lett. 2004 Dec 1;29(23):2797-9. doi: 10.1364/ol.29.002797.


A differential-phase-shift quantum key distribution experiment was carried out with a planar light-wave circuit (PLC) Mach-Zehnder interferometer. This scheme has two advantages: it requires no polarization control and has a high repetition frequency, provided that a stable interferometer is available. Stable polarization-insensitive operation was achieved with an interferometer fabricated by PLC technology. Raw key creation at a rate of 3076 bits/s with a 5.0% quantum bit-error rate was achieved over 20 km of fiber. The stability of the PLC interferometer was examined.