  A trapped atom interferometer involving state-selective adiabatic potentials
with two microwave frequencies on a chip is proposed. We show that this
configuration provides a way to achieve a high degree of symmetry between the
two arms of the interferometer, which is necessary for coherent splitting and
recombination of thermal (i.e. non-condensed) atoms. The resulting
interferometer holds promise to achieve high contrast and long coherence time,
while avoiding the mean-field interaction issues of interferometers based on
trapped Bose-Einstein condenstates.
