J. Ro nagel,1 O. Abah,2 F. Schmidt-Kaler,1 K. Singer,1 and E. Lutz2
1Quantum, Institut fur Physik, Universitat Mainz, D-55128 Mainz, Germany
2 Institute for Theoretical Physics, University of Erlangen-Nurnberg, D-91058 Erlangen, Germany
(Dated: January 9, 2014)
We consider a quantum Otto cycle for a time-dependent harmonic oscillator coupled to a squeezed thermal reservoir. We show that the e ciency at maximum power increases with the degree of squeezing, surpassing the standard Carnot limit and approaching unity exponentially for large squeezing parameters. We further propose an experimental scheme to implement such a model system by using a single trapped ion in a linear Paul trap with special geometry. Our analytical investigations are supported by Monte Carlo simulations that demonstrate the feasibility of our proposal. For realistic trap parameters, an increase of the e ciency at maximum power of up to a factor of four is reached, largely exceeding the Carnot bound.
1Quantum, Institut fur Physik, Universitat Mainz, D-55128 Mainz, Germany
2 Institute for Theoretical Physics, University of Erlangen-Nurnberg, D-91058 Erlangen, Germany
(Dated: January 9, 2014)
We consider a quantum Otto cycle for a time-dependent harmonic oscillator coupled to a squeezed thermal reservoir. We show that the e ciency at maximum power increases with the degree of squeezing, surpassing the standard Carnot limit and approaching unity exponentially for large squeezing parameters. We further propose an experimental scheme to implement such a model system by using a single trapped ion in a linear Paul trap with special geometry. Our analytical investigations are supported by Monte Carlo simulations that demonstrate the feasibility of our proposal. For realistic trap parameters, an increase of the e ciency at maximum power of up to a factor of four is reached, largely exceeding the Carnot bound.
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| Nanoscale heat engine |
Heat engines are important devices that convert heat into useful mechanical work. Standard heat engines run
cyclically between two thermal (equilibrium) reservoirs at diff erent temperatures T1 and T2. The second law of thermodynamics restricts their e ciencies to the Carnot limit, n1= 1 - T1/T2 (T1
Triggered by the pioneering study of Scovil and Schulz-DuBois on maser heat engines [2] and boosted by the advances in nanofabrication, an intense theoretical e ort has been devoted to the investigation of their properties in the quantum regime, see e.g. Refs. [3{11]. In particular, theoretical studies have indicated that the effi ciency of an engine may be increased beyond the standard Carnot bound by coupling it to an engineered (nonequilibrium) quantum coherent [12] or quantum correlated [13] reservoir (see also the related Refs. [14{17] for photocell heat engines). These stationary nonthermal reservoirs are characterized by a temperature as well as additional parameters that quantify the degree of quantum coherence or quantum correlations. The maximum e ciency that can be reached in this nonequilibrium setting is limited by a
generalized Carnot e ciency that can surpass the standard Carnot value [18]. Quantum reservoir engineering
techniques are powerful tools that enable the realization of arbitrary thermal and nonthermal environments [19]. Those techniques have rst been experimentally demonstrated in ion traps [20]. Recently, they have been used to produce nonclassical states, such as entangled states, in superconducting qubits [21] and atomic ensembles [22], as well as in circuit QED [23] and ion trap systems [24].
DOI:
10.1103/PhysRevLett.112.030602
PACS:
05.70.-a, 37.10.Ty, 37.10.Vz
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