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                      DIPARTIMENTO DI MATEMATICA 
 
                   UNIVERSITA' DI ROMA "LA SAPIENZA" 
 
                  Settimana dal 6 al 12 ottobre 2014 
 
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Lunedi' 6 ottobre 2014 
 
Ore 16:30, Aula C 
Seminario di Probabilità e Fisica Statistica 
Marco Ribezzi Crivellari (Universita' di Barcellona) 
Experimental measurements of entropy production at the nano-scale: an 
application for the 'fluctuation theorems' 
 
The study of non-equilibrium systems has led to several mathematically 
rigorous and general results on the statistics of entropy production 
in non-equilibrium systems. These results are generally known under 
the name of 'fluctuation theorems' and include the Gallavotti-Cohen 
theorem or the Jarzynski equality. My research focuses on performing 
experiments in which such results can be tested in real physical 
systems. I am interested in assessing their range of validity but even 
more interested in exploiting them to develop new measurement 
techniques. I will present some recent experiments, in which focused 
laser beams (optical tweezers) are used to perform thermodynamic 
transformations on single DNA molecules. As a first example I will 
show how to use fluctuation theorems to measure the free energy change 
across the transformation. As a second example I will discuss how, in 
specific cases, fluctuation theorems can be used to measure the full 
entropy production in a nano-scale system starting from a partial 
measurement through what we call an 'inference' procedure. This last 
example provides a new and general application of fluctuation theorems 
which we are only beginning to explore.