Mukherjee, Victor and Divakaran, Uma and Dutta, Amit and Sen, Diptiman (2008) Quenching dynamics of a quantum XY spin1/2 chain in the presence of transverse field by the application of a generalized Landau Zener formula. In: PRAMANAJOURNAL OF PHYSICS, 71 (2). pp. 403412.

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Abstract
In this paper we review the quenching dynamics of a quantum XY spin1/2 chain in the presence of a transverse field, when the transverse field or the anisotropic interaction is quenched at a slow but uniform rate. We also extend the results to the cases in which the system starts with any arbitrary initial condition as opposed to the initial fully magnetically aligned state which has been extensively studied earlier. The evolution is nonadiabatic in the time interval when the parameters are close to their critical values, and is adiabatic otherwise. The density of defects produced due to nonadiabatic transitions is calculated by mapping the manyparticle system to an equivalent Landau{Zener problem. We show that in one dimension the density of defects in the final state scales as $ \[ \frac {1}{\sqrt{\tau}}\] $ irrespective of the initial condition, where $ \tau $ is the quenching timescale. However, the magnitude of density of defects is found to depend on the initial condition.
Item Type:  Journal Article 

Additional Information:  Copyright of this article belongs to Indian Academy of Sciences. 
Keywords:  Transverse XY model;quantum phase transition;Landau{Zener. 
Department/Centre:  Division of Physical & Mathematical Sciences > Centre for High Energy Physics 
Date Deposited:  15 May 2009 06:23 
Last Modified:  19 Sep 2010 04:50 
URI:  http://eprints.iisc.ernet.in/id/eprint/15978 
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