Tunable two-axis spin model and spin squeezing in two cavities
Yu Lixian1, Li Caifeng2, 3, Fan Jingtao2, Chen Gang2, 5, Zhang Tian-Cai4, 5, Jia Suotang2, 5
       

(a) Proposed experimentally-feasible setup that an ensemble of ultracold six-level atoms interacts with two quantized cavity fields and two pairs of Raman lasers. A couple of orthogonally placed cavities Ca and Cb are arranged in a specific plane, and a guided magnetic field B is applied along one of the two cavities (see, for example, Ca) to fix a quantized axis and split the Zeeman sublevels of the atomic ensemble. Both the cavity modes and Raman lasers propagated in Ca (Cb) are assumed to be right-handed circularly polarized (linearly polarized along the guided magnetic field B). (b) Energy-level structure and their transitions induced by two photon modes and two pairs of Raman lasers. For 87Rb atom, the detailed levels can be chosen as |0⟩ → 5S1/2 |F = 1,mF = 0⟩, |1⟩ → 5S1/2 |F = 2,mF = 0⟩, |r1⟩ → 5P1/2 |F = 1,mF = 0⟩, |s1⟩ → 5P3/2 |F = 1,mF = 0⟩, |r2⟩ → 5P1/2 |F = 1,mF = −1⟩, and |s2⟩ → 5P3/2 |F = 1,mF = −1⟩. In such an arrangement, the transitions labeled by the red lines (blue lines) are thus π transitions (σ transitions).