Configuration-space quantum-soliton model including loss and gain

We examine the effects of loss and gain on a quantum soliton using a config uration-space approach. A simple microscopic model of local photon-matter i nteraction is applied to solitons with arbitrary quantum superpositions of momentum. Such a theory is needed in the analysis and design of systems tha t manipulate the wave function of soliton center-of-mass coordinates. The f ormalism is tested by calculating the momentum noise induced by loss and ga in, and by comparison with the well-known Gordon-Haus calculation [J. P. Go rdon and H. A. Haus, Opt. Lett. 11, 665 (1986)]. The comparison provides ph ysical insight and reproduces the old result as a special case. [S1050-2947 (99)03909-8].