Quantum lubrication: Suppression of friction in a first-principles four-stroke heat engine

Abstract

A quantum model of a heat engine resembling the Otto cycle is employed to explore strategies to suppress frictional losses. These losses are caused by the inability of the engine's working medium to follow adiabatically the change in the Hamiltonian during the expansion and compression stages.By adding external noise to the engine frictional losses can be suppressed.

Irreversibility in a unitary finite-rate protocol: the concept of internal friction

“…Therefore, the role of internal friction in quantum thermal devices has been devoted a considerable attention, recently [1,2,3,4,5,6,7,8,9,10,11,12,13,14]. As expected, the quantum friction is found to limit the performance of the quantum heat/refrigerator devices.…”

“…In the present contribution, we investigate the concept of internal friction, which is the irreversibility in closed quantum systems and arises when a quantum system undergoes nonideal, finite-time parametric adiabatic transformation [4,5,6,7,8]. Consider a parametrically driven quantum system with a time-dependent Hamiltonian, H(t).…”

“…If we are to use these quantum systems for useful purposes, such as heat to work conversion (i.e, as a quantum heat engine), we have to deal with the limitations imposed by quantum mechanics, such as quantum friction, on the thermodynamical transformations and cycles [1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18]. Quantum friction is the hallmark of finite-time thermodynamical transformations.…”

Speed and efficiency limits of multilevel incoherent heat engines

“…In the Otto cycle, attempts to allow for strokes of finite duration have been primarily confined, for both classical and quantum-mechanical HEs, to slow operation, as in the Curzon-Ahlborn analysis, which shows that efficiency drops as the speed (cycle rate) increases [4][5][6]. Likewise, for a driven three-level working fluid (WF) the speed of continuous-cycle operation has been shown to be detrimental, leading to friction, i.e., loss of work at the expense of wasted heat production [3][4][5][6][7][8][9][10][11][12][13][14][15].…”

“…Such operation avoids possible friction [3,7,[12][13][14][15]. These HEs are comprised of a frequency-modulated N -level WF described by, e.g., molecular angular-momentum giant spin or harmonicoscillator models, i.e.…”