Abstract
We present a new generalized Dicke model, an impurity-doped Dicke model (IDDM), by the use of an impurity-doped cavity-Bose-Einstein condensate (BEC). It is shown that the impurity atom can induce Dicke quantum phase transition (QPT) from the normal phase to superradiant phase at a critic value of the impurity population. It is found that the impurity-induced Dicke QPT can happen in an arbitrary field-atom coupling regime while the Dicke QPT in the standard Dicke model occurs only in the strong coupling regime of the cavity field and atoms. This opens the possibility to realize the control of quantum properties of a macroscopic-quantum system (BEC) by using a microscopic quantum system (a single impurity atom).
Highlights
In recent years ultracold atoms in optical cavities have revealed themselves as attractive new systems for studying strongly-interacting quantum many-body theories
We show that the impurity atom can induce the Dicke quantum phase transition (QPT) from the normal phase to the superradiant phase with the impurity population being the QPT parameter
A two-level impurity atom with energy splitting ωQ is doped in an atomic Bose-Einstein condensate (BEC), which is confined in a ultrahigh-finesse optical cavity
Summary
In recent years ultracold atoms in optical cavities have revealed themselves as attractive new systems for studying strongly-interacting quantum many-body theories. One example, which has been extensively studied theoretically and experimentally, is the Dicke quantum phase transition (QPT) from the normal phase to the superradiant phase with a Bose-Einstein condensate (BEC) in an optical cavity[1,2,3,4,5,6,7,8,9,10]. The Dicke model[11] describes a large number of two-level atoms interacting with a single cavity field mode, and predicts the existence of the Dicke QPT10, 12–15 from the normal phase to the superradiant phase. In the Dicke QPT experimental realization[2], the normal phase corresponds to the BEC being in the ground state associated with vacuum cavity field state while both the BEC and cavity field have collective excitations in the super-radiant phase. This opens a possibility to observe the Dicke QPT in the intermediate and even weak coupling regime of the cavity field and atoms
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