cfaed Seminar Series

cfaed Seminar Series

Prof. Alessio Gagliardi , Technische Universität München

Information theory and thermodynamics: a way to formalize systems out of thermodynamic equilibrium

03.06.2016 (Friday) , 13:00 - 14:00
Seminar Room 115 (HAL) , Hallwachsstr. 3 , 01169 Dresden

The idea of developing a thermodynamic theory of systems under an external feedback
dates back to the origin of statistical physics when Maxwell made his famous gedanken
experiment concerning the effect of a Demon with some information about the system and
the effect on the thermodynamics of the system itself. Recently this branch of
thermodynamics has got a rapid boost thank to fluctuation theorems. An interesting
complementary perspective comes from a branch of information theory named Large
deviation theory (LDT). LDT is the mathematical framework which copes with the probability
of large fluctuations departing from the average ensemble values of statistical quantities. In
particular LDT demonstrates that for a large class of probability density functions (PDF),
defined on the phase space, the probability of having a fluctuation respect to the average
value drops exponentially. The exponent is related to the Legendre-Fenchel transform of the
scaled cumulant generating function. It has been demonstrated that the LDT provides a very
elegant way to derive the thermodynamic principles of maximum entropy and minimal free
energy for the microcanonical and canonical ensemble respectively in thermodynamic
equilibrium. Extension to non equilibrium conditions have been investigated.
We present here an extension of the formalism that allows to use LDT also for systems under
an external feedback, in particular we show how it is possible to define a direct connection
between the measurement performed by the feedback and its accuracy and the maximum
entropy reduction that can be achieved with that feedback. Moreover it will be shown how the
formalism can actually be generalized in order to tackle also problems related to non
equilibrium thermodynamics such as molecular junctions under an external bias.

Alessio Gagliardi received his doctorate in physics from the University of
Paderborn in 2007 under the supervision of Professor Thomas
Frauenheim. He then worked as a postdoctoral researcher at the Bremen
Center for Computational Material Science.
In 2008 he moved back to Rome where he worked as a postdoctoral
researcher in the group of Prof. Aldo Di Carlo. In January 2014 he was
appointed Assistant Tenure Track Professor for the Simulation of
Nanosystems for Energy Conversion group at the Technische Universit¨at
M¨unchen (TUM). The research of Prof. Gagliardi focuses on
nanostructured devices for energy harvesting. A major focus of his
research is on simulating third generation photovoltaic devices, such as
dye sensitized solar cells and organic photovoltaic cells using
driftdiffusion approximation. He is a developer of the TiberCAD and
GDFTB software tools.

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