Entanglement death and purity loss in a superconducting qubit coupled to a dephasing cavity

Analytical description of the dynamics of a superconducting qubit interacting with a resonator cavity coupled to its reservoir is presented. When the detuning between the junction energy and resonator frequency takes different values, the entanglement death and purity loss are investigated. It is found that the dephasing of the resonator cavity leads to persistent purity loss and entanglement death of the SC-qubit, they remain nearly invariant regardless of the increase of time. Entanglement death and purity loss can be enhanced when the SC-qubit is kept off-resonant with the resonator.