First-order quantum phase transition and entanglement in the Jaynes–Cummings model with a squeezed light

We study the quantum phase transition and entanglement in the Jaynes–Cummings model with squeezed light, utilize a special transformation method to obtain the analytical ground state of the model within the near-resonance regime, and numerically verify the validity of the analytical ground state. It is found that the ground state exhibits a first-order quantum phase transition at the critical point linearly induced by squeezed light, and the ground state entanglement reaches its maximum when the qubit-field coupling strength is large enough at the critical point.