  We study the effect of a noisy environment on spin and charge transport in
ballistic quantum wires with spin-orbit coupling (Rashba coupling). We find
that the wire then acts as a ``dephasing diode'', inducing very different
dephasing of the spins of right and left movers. We also show how Berry phase
(geometric phase) in a curved wire can induce such asymmetric dephasing, in
addition to purely geometric dephasing. We propose ways to measure these
effects through spin detectors, spin-echo techniques, and Aharanov-Bohm
interferometry.
