Collège Doctoral - Doktorandenkollegien

Statistical Physics of Complex Systems

Coventry - Leipzig - Lviv - Nancy

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Seminar

Out of equilibrium process in quantum spin chains
Thierry Platini
platini AT lpm DOT u-nancy DOT fr
Laboratoire de Physique des Matériaux (Nancy 1)
le Thursday 15 November 2007 à 16h00
Seminar room ITP Leipzig
We present the results obtained on the magnetisation relaxation properties of the XX and Ising quantum chains in a transverse magnetic field. We first consider an initial thermal kink-like state where half of the chain is initially thermalized at a very high temperature $T_b$ while the remaining half, called the system, is put at a lower temperature $T_s$. In this case the front dynamic is studied. We derive analytically the Green function associated to the dynamical behaviour of the transverse magnetisation. Depending on the strength of the magnetic field and on the temperature of the system, different regimes are obtained for the magnetic relaxation. In particular, with an initial cold subsystem of finite size in contact at both ends with an infinite temperature environnement, we derive analytically the behaviour of the time-dependent system magnetisation.


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