B.-Q. Jin and V. E. Korepin
Entanglement, Toeplitz Determinants 
 and Fisher-Hartwig Conjecture
(277K, PostScript)

ABSTRACT.  We consider one-dimensional quantum spin chain, which is called 
XX model (sometimes it is called XX0 model or isotropic XY model) in 
a transverse magnetic field. 
 We are interested in the case of zero temperature and infinite volume. 
 We study the entanglement of a block L of neighboring spins with the 
 rest of the system. We represent the entanglement in terms of a 
Toeplitz determinant and calculate the asymptotic analytically . 
 We derive first two terms of asymptotic decomposition.