Quantum thermodynamic cooling cycle - art. no. 056130

The quantum-mechanical and thermodynamic properties of a three-level molecu lar cooling cycle are derived. An inadequacy of earlier models is rectified in accounting for the spontaneous emission and absorption associated with the coupling to the coherent driving field via an environmental reservoir. This additional coupling need not be dissipative, and can provide a thermal driving force-the quantum analog of classical absorption chillers. The dep endence of the maximum attainable cooling rate on temperature, at ultralow temperatures. is determined and shown to respect the recently established f undamental bound based on the second and third laws of thermodynamics.