Fiber Optics Upgrades Cryptography

An autocompensating quantum cryptography technique based upon manipulating a pulse of light split into equal orthogonally polarized components has received a significant upgrade with the integration of fiber optics into the coding/decoding process.

Designed by IBM's Almaden Research Center in San Jose, Calif., the technique previously used bulk optics to generate coded information at approximately 200 b/s with a 5 percent bit error rate. As reported in the March 20 issue of Applied Optics, the replacement of these optics with fiber technology produced a speed of 1.5 kb/s with a 1.5 percent bit error rate -- attributed largely to a reduction in noise from backscattering and signal attenuation.