Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The unlikely Carnot efficiency   The efficiency of an heat engine is traditionally defined as the ratio of its
average output work over its average input heat. Its highest possible value was
discovered by Carnot in 1824 and is a cornerstone concept in thermodynamics. It
led to the discovery of the second law and to the definition of the Kelvin
temperature scale. Small-scale engines operate in the presence of highly
fluctuating input and output energy fluxes. They are therefore much better
characterized by fluctuating efficiencies. In this study, using the fluctuation
theorem, we identify universal features of efficiency fluctuations. While the
standard thermodynamic efficiency is, as expected, the most likely value, we
find that the Carnot efficiency is, surprisingly, the least likely in the long
time limit. Furthermore the probability distribution for the efficiency assumes
a universal scaling form when operating close-to-equilibrium. We illustrate our
results analytically and numerically on two model systems.

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The categories of this paper are: mtrl-th
7
The categories of this paper are: hep-th
21
The categories of this paper are: adap-org
34
The categories of this paper are: chem-ph
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The categories of this paper are: comp-gas
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The categories of this paper are: patt-sol
9
The categories of this paper are: nlin
6
The categories of this paper are: astro-ph
8
The categories of this paper are: hep-ex
20
The categories of this paper are: acc-phys
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The categories of this paper are: eess
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The categories of this paper are: math-ph
15
The categories of this paper are: nucl-ex
3
The categories of this paper are: physics
12
The categories of this paper are: nucl-th
2
The categories of this paper are: math