Editing Reciprocating engine (section)

==Reciprocating quantum heat engine==
[[Quantum heat engines]] are devices that generate power from heat that flows from a hot to a cold reservoir.
The mechanism of operation of the engine can be described by the laws of [[quantum mechanics]]. 
[[Quantum refrigerators]] are devices that consume power with the purpose to pump heat from a cold to a hot reservoir.

In a reciprocating quantum heat engine, the working medium is a quantum system such as spin systems or a harmonic oscillator.
The [[Carnot cycle]] and [[Otto cycle]] are the ones most studied.<ref>[http://iopscience.iop.org/1367-2630/8/5/083/fulltext/] Irreversible performance of a quantum harmonic heat engine, Rezek and Kosloff, New J. Phys. 8 (2006) 83</ref>
The quantum versions obey the laws of [[thermodynamics]]. In addition, these models can justify the assumptions of
[[endoreversible thermodynamics]].
A theoretical study has shown that it is possible and practical to build a reciprocating engine that is composed of a single oscillating atom. This is an area for future research and could have applications in [[nanotechnology]].<ref>[http://phys.org/news/2012-11-car-built-particle.html Can a car engine be built out of a single particle?] Physorg,  November 30, 2012 by Lisa Zyga. Accessed 01-12-12</ref>