QUANTUM COHERENCE IN AN EXACTLY SOLVABLE ONE-DIMENSIONAL MODEL WITH DEFECTS - COMMENTS

In a recent paper by Schmitteckert et al., an exactly solvable XXZ cha in with defects was studied. We here point out that, for this type of model, the critical exponents for the asymptotic correlation functions are insensitive to the presence of defects. Also, the defects do not enhance the persistent current of the equivalent fermionic model, cont rary to a claim by Schmitteckert et al.