Seminário de Computação e Informação Quântica   RSS

12/03/2018, 16:00 — 17:00 — Sala de seminários (2.8.3), Pavilhão de Física
, Weizmann Institute of Science

Quantum and classical thermodynamic machines: work, power, cooling

Heat engine efficiency is limited by the Carnot bound. However, Scully et al. [Science 299, 862(2003)] bypassed this bound by allowing for extra heat input, and hence a higher hot-bath temperature, via coherence in the working fluid. In recent years, squeezed thermal baths have been claimed to yield extra heat input and hence surpass the Carnot bound [Rossnagel et al., PRL 112, 030602 (2014)]. However, the latter claim is unfounded, since squeezed baths transfer not just heat but also work to the working fluid, as shown by us [Gelbwaser-Klimovsky et al., NJP 18, 083012 (2016)]. Consequently, such engines are no longer heat engines but more like mechanical engines, and hence the Carnot bound is irrelevant to them. We have recently formulated a universal theory of any quantum or classical machines, fueled by arbitrary heat and work reservoirs [W. Niedenzu et al., Nature Commun. (2017)], which shows that what counts for maximal efficiency is the minimal loss of energy to the cold bath, which may be completely different from a Carnot bound if the baths are non-thermal. The crucial feature that allows for maximal work and power is maximized non-passivity (ergotropy) of the working fluid and/or the piston, as shown by us lately for a heat engine whose piston is squeezed by a pump [A. Ghosh et al., PNAS 2017]. Analogous considerations apply to cooling / refrigeration performance.

Apoiado por: Phys-Info (IT), SQIG (IT), CeFEMA e CAMGSD, com financiamento de FCT, FEDER and EU FP7, especificamente via o Doctoral Programme in the Physics and Mathematics of Information (DP-PMI), os projectos estratégicos FCT PEst-OE/EEI/LA0008/2013 e UID/EEA/50008/2013, o projecto IT QuSim, o projecto CRUP-CPU CQVibes, a Acção de Coordenação FP7 QUTE-EUROPE (600788) e os projectos FP7 Landauer (GA 318287) e PAPETS (323901).

Instituto de TelecomunicaçõesCAMGSDFCT7th Framework Programme