Quenching along a gapless line: A different exponent for defect density

Divakaran, Uma and Dutta, Amit and Sen, Diptiman (2008) Quenching along a gapless line: A different exponent for defect density. In: Physical Review B: Condensed Matter and Materials Physics, 78 (14). pp. 144301-1.

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Abstract

We use a quenching scheme to study the dynamics of a one-dimensional anisotropic XY spin-1/2 chain in the presence of a transverse field which alternates between the values h+delta and h−delta from site to site. In this quenching scheme, the parameter denoting the anisotropy of interaction (gamma) is linearly quenched from −[infinity] to +[infinity] as gamma=t/tau, keeping the total strength of interaction J fixed. The system traverses through a gapless phase when gamma is quenched along the critical surface h2=delta2+J2 in the parameter space spanned by h, delta, and gamma. By mapping to an equivalent two-level Landau-Zener problem, we show that the defect density in the final state scales as 1/tau1/3, a behavior that has not been observed in previous studies of quenching through a gapless phase. We also generalize the model incorporating additional alternations in the anisotropy or in the strength of the interaction and derive an identical result under a similar quenching. Based on the above results, we propose a general scaling of the defect density with the quenching rate tau for quenching along a gapless critical line.

Item Type:	Journal Article
Publication:	Physical Review B: Condensed Matter and Materials Physics
Publisher:	The American Physical Society
Additional Information:	Copyright of this article belongs to The American Physical Society.
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	07 Sep 2009 08:38
Last Modified:	19 Sep 2010 04:57
URI:	http://eprints.iisc.ac.in/id/eprint/17523

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