  We consider a type of Quantum Electro-Mechanical System, known as the shuttle
system, first proposed by Gorelik et al., [Phys. Rev. Lett., 80, 4526, (1998)].
We use a quantum master equation treatment and compare the semi-classical
solution to a full quantum simulation to reveal the dynamics, followed by a
discussion of the current noise of the system. The transition between
tunnelling and shuttling regime can be measured directly in the spectrum of the
noise.
