Condensed Matter Physics, 2009, vol. 12, No. 3, pp. 369-380

Title: The emptiness formation probability correlation in homogeneous and dimerized XX chains
  J. Stolze (Institut für Physik, Technische Universität Dortmund, 44221 Dortmund, Germany) ,
  T. Garske (Institut für Physik, Technische Universität Dortmund, 44221 Dortmund, Germany; MRC Centre for Outbreak Analysis and Modelling, Department of Infectious Disease Epidemiology, Imperial College London, Norfolk Place, London W2 1PG, UK [present address])

We review some known properties of the "emptiness formation probability" correlation which we have calculated numerically for spin-1/2 XX chains with constant (homogeneous) or alternating (dimerized) nearest-neighbor coupling and an external field (in z direction) for arbitrary temperature. The long-distance asymptotic behavior of this correlation is known to be Gaussian at zero temperature and exponential at finite temperature for the homogeneous chain. By simple analytical arguments the exponential behavior at finite temperature extends to the dimerized system. Numerical results for the dimerized chain confirm the exponential decay at finite temperature and show Gaussian decay at zero temperature.

Key words: emptiness formation probability, XX chain, Pfaffian
PACS: 75.10.Jm, 75.10.Pq
Comments: Figs. 10, Refs. 29, Tabs. 0

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