Power Law Corrections to BTZ Black Hole Entropy
  We study the quantum scalar field in the background of BTZ black hole and evaluate the entanglement entropy of the non-vacuum states. The entropy is proportional to the area of event horizon for the ground state, but the area law is violated in the case of non-vacuum states (first excited state and mixed states) and the corrections scale as power law. 
Dharm Veer Singh
hep-th gr-qc