Universal Thermal Corrections to Single Interval Entanglement Entropy for Conformal Field Theories

Understand

We consider single interval R\'enyi and entanglement entropies for a two dimensional conformal field theory on a circle at nonzero temperature.

• Assuming that the finite size of the system introduces a unique ground state with a nonzero mass gap, we calculate the leading corrections to the R\'enyi and entanglement entropy in a low temperature expansion.
• These corrections have a universal form for any two dimensional conformal field theory that depends only on the size of the mass gap and its degeneracy.
• We analyze the limits where the size of the interval becomes small and where it becomes close to the size of the spatial circle.