  We examine the dynamics of a qubit stored in the motional degrees of freedom
of an ultra-cold ion in an ion trap which is subject to the decoherence effects
of a finite-temperature bath. We discover an encoding of the qubit, in two of
the motional modes of the ion, which is stable against the occurrence of either
none or one quantum jump. For the case of a zero-temperature bath we describe
how to transfer only the information concerning the occurrence of quantum jumps
and their types to a measuring apparatus, without affecting the ion's motional
state significantly. We then describe how to generate a unitary restoration of
the qubit given the jump information, through Raman processes generated by a
series of laser pulses.
