Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: The scaling of the decoherence factor of a qubit coupled to a spin chain
  driven across quantum critical points   We study the scaling of the decoherence factor of a qubit (spin-1/2) using
the central spin model in which the central spin (qubit) is globally coupled to
a transverse XY spin chain. The aim here is to study the non-equilibrium
generation of decoherence when the spin chain is driven across (along) quantum
critical points (lines) and derive the scaling of the decoherence factor in
terms of the driving rate and some of the exponents associated with the quantum
critical points. Our studies show that the scaling of logarithm of decoherence
factor is identical to that of the defect density in the final state of the
spin chain following a quench across isolated quantum critical points for both
linear and non-linear variations of a parameter even if the defect density may
not satisfy the standard Kibble-Zurek scaling. However, one finds an
interesting deviation when the spin chain is driven along a critical line. Our
analytical predictions are in complete agreement with numerical results. Our
study, though limited to integrable two-level systems, points to the existence
of a universality in the scaling of the decoherence factor which is not
necessarily identical to the scaling of the defect density.

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The categories of this paper are: hep-th
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The categories of this paper are: math-ph
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The categories of this paper are: econ
31
The categories of this paper are: ao-sci
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The categories of this paper are: alg-geom
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The categories of this paper are: eess
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The categories of this paper are: acc-phys
0
The categories of this paper are: hep-ph
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The categories of this paper are: hep-ex
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The categories of this paper are: dg-ga
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The categories of this paper are: q-bio
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The categories of this paper are: q-fin
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The categories of this paper are: patt-sol
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The categories of this paper are: math
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The categories of this paper are: cs
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The categories of this paper are: chem-ph