Thermo-field dynamics of higher-derivative oscillators

The higher-derivative oscillator proposed by Pais and Uhlenbeck has a well-defined Hamiltonian formulation in terms of a system of harmonic oscillators, which allows consistent quantum treatment. In this report we consider a system of interacting Pais-Uhlenbeck oscillators and calculate their entanglement entropy using the framework of thermo-field dynamics. We also make connection with information theory via the Fisher information metric and with the AdS/CFT correspondence via the supergravity solution of Pilch and Warner.