  We consider the quantum version of Arnold's generalisation of a rigid body in
classical mechanics. Thus, we quantise the motion on an arbitrary Lie group
manifold of a particle whose classical trajectories correspond to the geodesics
of any one-sided-invariant metric. We show how the derivation of the spectrum
of energy eigenstates can be simplified by making use of automorphisms of the
Lie algebra and (for groups of Type I) by methods of harmonic analysis. We show
how the method can be extended to cosets, generalising the linear rigid rotor.
As examples, we consider all connected and simply-connected Lie groups up to
dimension 3. This includes the universal cover of the archetypical rigid body,
along with a number of new exactly-solvable models. We also discuss a possible
application to the topical problem of quantising a perfect fluid.
