Ground state correlation functions of the XY spin chain in a random transverse field
The single-body and anomalous (pair) correlation functions of Jordan-Wigner fermions in the ground state of a disordered XY chain are calculated. Disorder is introduced into this system as a site-dependent transverse field taken from a uniform distribution of fixed width and within the ferromagnetic phase. Results show that increasing the disorder strength by increasing the distribution width leads to a more rapid decay of correlations within the bulk. The average local transverse magnetization of the spin chain decreases with increasing disorder strength, having greater fluctuations in the middle bulk of the chain.