  We examine here a hitherto unchartered Ericsson motor, operating in the
quantum domain. The engine is a nanoscopic system of an electron trapped in a
two-dimensional parabolic well and further subjected to an external magnetic
field in the third direction. The quantum-coherent cyclotron motion of the
electron is de-cohered due to strong interaction with a dissipative quantum
heat bath.The calculation employs two different approaches - exact functional
integral representation of the partition function and quantum Langevin
equations for the operators of the system. Though in equilibrium, both the
approaches yield equivalent expressions for the efficiency, the Langevin method
opens up further avenues for investigating time dependent properties of the
nano motor.
