CMSP Section announces 3 seminars soon

Cond.Matt. & Stat.Mech.Section cm at
Mon Nov 26 12:13:14 CET 2012


Tuesday, 27 November   -   11:30 hrs.

Luigi Stasi Seminar Room -  ICTP Leonardo Building - 1st floor

Alejandro B. KOLTON    ( Centro Atomico Bariloche ) 

"Infinite family of second-law-like inequalities"


The probability distribution function for an out of equilibrium system may sometimes be approximated by a physically motivated "trial" distribution. A particularly interesting case is when a driven system (e.g., active matter) is approximated by a thermodynamic one. We show here that every set of trial distributions yields an inequality playing the role of a generalization of the second law. This suggests a variational procedure that may be implemented numerically and even experimentally to approximate the distribution function in terms of effective interactions. The fluctuation relation behind this inequality, -a natural and practical extension of the Hatano-Sasa theorem-, does not rely on the a priori knowledge of the stationary probability distribution.



Wednesday, 28 November   -   11:00 a.m.

SISSA, Santorio Building,  Room 138 (1st Floor)

R. TATEO   (University of Torino)

" An alternative road to  Bethe Ansatz equations"


In the last few years, a link between Bethe Ansatz equations for conformal field theories and spectral functions of simple ordinary differential operators has emerged.  Assuming no prior knowledge of this topic, this talk will review the key facts about this surprising link and discuss recent important findings concerning its off-critical generalisation.


SEMINAR  on  Disorder and strong electron correlations

Thursday, 29 November-  11:30 a.m. 

Luigi Stasi Seminar Room,  Leonardo Building - first floor

Chiara D'ERRICO  (LENS & University of Florence & INO-CNR)

"The phase diagram of one-dimensional  disordered bosons at ultralow temperature"


The interplay of disorder and interactions can have a large impact on the properties of quantum systems.  It is well known that, whereas non-interacting particles can be localized by the destructive interference in a disordered potential, a weak repulsive interaction tends to establish coherence between single-particle localized states, thus weakening or destroying such localization.  The interplay of disorder and strong interactions is instead still a challenging problem.  One paradigmatic problem is that of low-temperature bosonic particles confined to a one-dimensional disordered environment, which, in addition to the standard superfluid and Mott phases, has been predicted to show a peculiar gapless insulating phase, the Bose glass [1,2], that is still proving to be elusive in experiments.  We investigate the behavior of a bosonic quantum gas close to T=0 confined in a one-dimensional quasi-periodic lattice, where interactions and disorder can be independently tuned.  By studying its momentum distribution, mobility and excitation spectrum features, we trace out a phase diagram showing a coherent phase surrounded by a gapless insulator.  The latter has a bosonic character at low interactions, and a fermionic one at large interactions, consistently with the expectations for the presence of a Bose glass phase.  Our results confirm long-standing theoretical predictions and indicate the way to study still open questions in 1D bosons and analogous disordered problems in higher dimensions and/or with fermions.

[1] D. S. Fisher, Phys.Rev. B 40, 546 (1989).
[2] T. Giamarchi, Phys. Rev. A 78, 023628 (2008).

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