Controlling entanglement dynamics of two qubits coupled to a common reservoir via a coherent field

Abstract

We investigate the time evolution of entanglement between two two-level atoms which are coupled to a common multimode electromagnetic reservoir and simultaneously driven by a coherent field. We find that the entanglement can always be created and maintained with a moderate intensity of the driving field during the track of approaching steady entangled states when both atoms are initially in their ground states and the reservoir is in the vacuum state or the squeezed vacuum state. We also show that the steady-state entanglement between the atoms can be enhanced by use of the coherent field when the reservoir is in the weakly squeezed vacuum state. More interestingly, in the squeezed reservoir case, the sudden death period in the time evolution of the entanglement can be removed by use of the coherent driving field.

Keywords:

• entanglement
• electromagnetical reservoir
• dipole–dipole interaction
• coherent field

Acknowledgements

This work was supported by the National Natural Science Foundation of China under Grant Nos. 60778021 and 10674106, and the National Key Project of Basic Research Development under Grant No. 2010CB923102.