Abstract

The fiber-optical Kerr effect produced unique nonclassical correlations through intensity-dependent phase shifts in a variety of squeezing and quantum-nondemolition (QND) experiments [1]. One squeezing mechanism makes use of spectral filtering of fiber-optical pulses. Our novel QND approach applies spectral filtering to two interacting solitons in order to obtain a QND readout. This QND coupling is immune to phase noise, produces directly detectable photon number correlations and is of high energy efficiency, because only two solitons are required. These solitons have different center frequencies and collide in a fiber because of the group-velocity dispersion. Their spectral separation is transiently enhanced during the collision, with the spectral shift of one soliton (probe) depending on the photon number of the other soliton (signal). The frequency shift is maximum at full temporal pulse overlap and using a spectral filter it is directly detectable.

© 2001 EPS