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

► Superconducting qubit interacting with a resonator cavity coupled to its reservoir considered. ► The entanglement death and purity loss are investigated with different values for the detuning. ► The dephasing leads to persistent purity loss and entanglement death of the SC qubit. ► Entanglement death and purity loss can be enhanced when the SC qubit is kept off resonant.