Entanglement entropy in extended quantum systems INTRODUCTION

Pasquale Calabrese, John Cardy, Benjamin Doyon

John Cardy

Jon Spalding, Shan-Wen Tsai

Pasquale Calabrese, John Cardy

We give a pedagogical and non-technical introduction to the quantum field theory approach to entanglement entropy. Particular attention is devoted to the one space dimensional case, with a linear dispersion relation, that, at a quantum critical point, can be effectively described by a two-dimensional conformal field theory.

K. Nakagawa

For the purpose of clarifying a new approach to understanding quantum entanglement using thermofield dynamics (TFD), entanglement entropies of non-equilibrium finite-spin systems are examined for both traditional and extended cases. The extended entanglement entropy, |$\hat {S}$|⁠, is derived, and it is found that the conditions for the maximum entangled state can be obtained through this approach. The capacity of the TFD-based method to distinguish between states in quantum systems is confirmed.

Durrani, Ijaz