Quantum phase transition of nonlinear light in the finite size Dicke Hamiltonian
B. M. Rodríguez-Lara, Ray‐Kuang Lee
We study the quantum phase transition of an N two-level system ensemble interacting with an optical degenerate parametric process, which can be described by the finite size Dicke Hamiltonian plus counter-rotating and quadratic field terms. Analytical closed forms of the critical coupling value and their corresponding separable ground states are derived in the weak and strong coupling regimes. The existence of bipartite entanglement between the two-level system ensemble and photon field as well as between ensemble components for moderate coupling is shown through numerical analysis. Given a finite size, our results also indicate the co-existence of squeezed fields and squeezed atomic ensembles.
arXiv:1005.3884•Journal of the Optical Society of America B•Oct 29, 2010•18 citations