A colliding-soliton switch that takes advantage of the conservation pr
operties of interacting solitons is demonstrated experimentally. We sh
ow that the switch, which can operate as an optical demultiplexer or a
s a logic gate, responds to incoming signal solitons without altering
them. This is a consequence of its quantum nondemolition measurement c
apabilities, and allows multiple operations to be performed with the s
ame soliton. Operation at rates exceeding 250 Gbit/s should be possibl
e.