Journal of High Energy Physics (Feb 2023)

The reflected entanglement spectrum for free fermions

  • Souvik Dutta,
  • Thomas Faulkner,
  • Simon Lin

DOI
https://doi.org/10.1007/JHEP02(2023)223
Journal volume & issue
Vol. 2023, no. 2
pp. 1 – 28

Abstract

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Abstract We consider the reflected entropy and the associated entanglement spectrum for free fermions reduced to two intervals in 1 + 1 dimensions. Working directly in the continuum theory the reflected entropy can be extracted from the spectrum of a singular integral equation whose kernel is determined by the known free fermion modular evolved correlation function. We find the spectrum numerically and analytically in certain limits. For intervals that almost touch the reflected entanglement spectrum approaches the spectrum of the thermal density matrix. This suggests that the reflected entanglement spectrum is well suited to the task of extracting physical data of the theory directly from the ground state wave function.

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