On the way to achieving long-lived mesoscopic superpositions through atom-driven field interaction

Carlos, PO Box 676, São Carlos, 13565-905, SP, Brazil. We present a proposal for the production of longer-lived mesoscopic superpositions which relies on two requirements: parametric amplification and squeezed vacuum reservoir for cavity-field states. Our proposal involves the interaction of a two-level atom with a cavity field which is simultaneously subjected to amplification processes. PACS numbers: 32.80.-t, 42.50.Ct, 42.50.Dv The mastery of techniques for preparing cavity-field states through atom-field interaction in cavity quantum electrodynamics (QED) is crucial to many useful applications in quantum optics. As high-Q cavities have permitted the preparation of cavity-field superpositions of the form |Ψ〉 = ∣∣α eiφ 〉 + ∣∣α e−iφ 〉) / √ 2, with mean number of oscillator quanta |α| ≈ 10, mesoscopic quantum coherence in cavity QED has been investigated: the progressive decoherence of the superposition |Ψ〉, involving radiation fields with classically distinct phases, was observed through atom-field interaction [1] and the reversible decoherence of such a cavity-field state has been conjectured [2]. In this letter we present a proposal for the achievement of long-lived mesoscopic superposition states in cavity QED which relies on two basic requirements: parametric amplification and an engineered squeezed-vacuum reservoir for cavity-field states. Our proposal considers the dispersive interaction of a two-level atom with a cavity field which is simultaneously under amplification processes. The parametric amplification is employed to achieve the required high degrees of squeezing and excitation