A quantum beat of quantum discord induced by the number of qubits in non-Markovian environments

Abstract

Abstract We investigate the protection of the quantum discord of two qubits, individually originated by two generalized amplitude-damping models. Here, each generalized amplitude-damping model consists of N non-interacting qubits interacting with a common zero-temperature reservoir. First, for initial states with extended Werner-like states, we find that the robust quantum discord of two qubits against decoherence can be obtained by controlling the number of qubits in the reservoir. More interestingly, we find that a quantum beat for quantum discord can occur when both the number of qubits in each reservoir is large and when the number of qubits have a tiny difference, even in the resonant case. Our results shed new light on the protection of quantum discord by means of a quantum-reservoir engineering approach in quantum-information processing.