Rank dependence of entanglement sudden death of a two-qubit system in a thermal reservoir

Abstract

Entanglement sudden death and revival of entanglement are generic features of the evolution of entangled quantum systems interacting with a thermal reservoir. We investigated the evolution of mixed entangled states of different ranks of two spatially separated qubits interacting through dipole forces and in contact with a common finite temperature photon bath. For a fixed initial concurrence, lower rank initial states exhibit ESD at later times. ESD time increases with increase in initial concurrence for a given mean number of photons, N in a bath. Further, ESD time decreases with increase in N. The choice of low rank mixed state with higher entanglement and low N of the bath can delay or even avoid ESD.