Entanglement entropy of the Silbey-Harris polaron ansatz for a spin-boson model


Proceedings of the 33rd Samahang Pisika ng Pilipinas Physics Congress, University of Northern Philippines, Vigan City, 3–6 Jun 2015, SPP-2015-PB-47.


We obtained the entanglement entropy between a qubit and a harmonic oscillator bath using a Silbey-Harris polaron ansatz. With the assumption that a single mode frequency is dominant, we calculated the exact dependence of the von Neumann entropy on the displacement parameter. The entanglement entropy increases and saturates exponentially fast to its maximum value of ln2 as the magnitude of the displacement increases. We also showed that the entanglement entropy depends on the sum of complex squares of each displacement when the bath is a multi-mode coherent state.