An N-qubit master equation and two-qubit entanglement dynamics in spin-chain and Bosonic environments

Abstract

The master equation for an N-qubit system immersed in an environment consisting of a reservoir of infinitely many modes of harmonic oscillators was derived. The master equation was then used to simulate the entanglement dynamics of two neighboring qubits by tracing out the other N-2 qubits. It was shown that if there are more than two qubits in the system, the concurrence between two qubits will not decay and will approach a steady state and that this steady state value increases with increasing number of qubits. The increase of steady state entangle- ment with increasing number of qubits can also be obtained with only a three-qubit system if the third qubit is strongly coupled to the environment.