Atom-molecule Dark State Research Articles

Adiabatic conversion of ultracold atoms to A3B-type tetrameric molecules

We investigate the conversion of ultracold bosonic atoms to heteronuclear tetramer A3B by an Efimov resonance-assisted stimulated Raman adiabatic passage scheme. In view of recent experiments involving heteronuclear Efimov trimers KKRb and KRbRb [Phys. Rev. Lett. 103, 043201 (2009)], the intermediate state populated by heteronuclear trimer A2B in the conversion process is considered. The atom-molecule dark state solution for a system with a population imbalance is derived analytically, and the role played by the imbalance in the conversion is studied. In addition, the effects of the external field parameters (including photoassociated pulse intensity, width, magnetic coupling strength and its detuning) on the conversion are discussed via the concept of adiabatic fidelity.

Slow-light probe of Fermi pairing through an atom-molecule dark state

We consider the two-color photooassociation of a quantum degenerate atomic gas into ground-state diatomic molecules via a molecular dark state. This process can be described in terms of a lambda level scheme that is formally analogous to the situation in electromagnetically-induced transparency (EIT) in atomic systems, and therefore can result in slow light propagation. We show that the group velocity of the light field depends explicitly on whether the atoms are bosons or fermions, as well as on the existence or absence of a pairing gap in the case of fermions, so that the measurement of the group velocity realizes a non-destructive diagnosis of the atomic state and the pairing gap.

Formation of a heteronuclear tetramerA3Bvia Efimov-resonance-assisted stimulated Raman adiabatic passage

We investigate the formation of a heteronuclear tetramer ${A}_{3}B$ by an Efimov-resonance-assisted stimulated Raman adiabatic passage scheme, which is considered a viable means of creating the homonuclear tetramer ${A}_{4}$ [H. Jing and Y. Jiang, Phys. Rev. A 77, 065601 (2008)]. The atom-molecule dark-state solution for the system is derived, and the adiabatic conversion from atoms to heteronuclear tetramers is studied via the concept of adiabatic fidelity. In addition, the effects of external field parameters (including Rabi pulse strength, width, and single photon detuning) on the conversion are discussed.

Quantum control of light through an atom-molecule dark state

We propose to use a quantized version of coherent two-color photoassociation to realize a hybrid device for quantum control of light. The dynamical features of this system are exhibited, including the slowing down or storage of light and the molecular matter-wave solitons. This may indicate a hybrid atom-molecule quantum device for storage and retrieve of optical information.

Creation of three-species 87Rb–40K–6Li molecules: interfering for the best

An ultracold three-species Bose–Fermi–Fermi degenerate atomic mixture 87Rb–40K–6Li was realized very recently (Tagliber M et al 2008 Phys. Rev. Lett. 100 010401). Here, we study the creation of heteronuclear triatomic molecules in this mixture, and show that a constructive triple-path interference can lead to an almost ideal conversion rate, in comparison with the single- or double-path cases. The important effect of the initial population imbalance on the atom–molecule dark state is also investigated.

Atom-Molecule Dark State: The Exact Quantum Solution

Developments in ultracold atomic physics have enabled the generation of an atom-molecule dark state in dilute quantum gases. Previous studies of this dark state were all carried out in the mean-field regime. Here we present an exact quantum many-body wave function for the atom-molecule dark state for an ideal system (in the absence of losses and two-body collisions). Using this exact quantum wave function, we are able to validate the mean-field solution to be a good approximation when the particle number N is large. For small N, unique quantum features will become important.

Coherent generation of triatomic molecules from ultracold atoms

We show that the use of a generalized atom-molecule dark state permits the enhanced coherent creation of triatomic molecules in a repulsive atomic Bose-Einstein condensate, with further enhancement being possible in the case of heteronuclear trimers via the constructive interference between two chemical reaction channels. The creation of fermionic trimers is also briefly discussed.

Nonlinear dynamical instabilities of a condensate system in an atom-molecule dark state

We study dynamics of a nonlinear three-level $\ensuremath{\Lambda}$ system describing Bose-Einstein condensates of atoms and diatomic molecules coupled by a two-color laser field. The system has a nonlinear dark state which is a generalization of the usual atomic dark state. In the recent paper [A. P. Itin and S. Watanabe, Phys. Rev. Lett. 99, 223903 (2007)], nonlinear instabilities of the dark state due to 1:1 and 1:2 resonances were discussed in the model without mean-field collisional interactions. Here we investigate the dark state of a model with collisional interactions. We show that nonlinear instabilities can be used, in particular, for precise determination of the scattering lengths.

Efimov Superchemistry: Quantum Dynamical Theory for Coherent Atom–Trimer Conversion in a Repulsive Atomic Bose–Einstein Condensate

We show that by making a generalized atom–molecule dark state, coherent creation of triatomic molecules can be enhanced in a repulsive atomic Bose–Einstein condensate. The dynamics of heteronuclear trimer creation is significantly different from the homonuclear case and further enhancement can be realized by controlling its chemical reaction channels. The possibility of manipulating atom–trimer conversion provides an appealing research area for current coherent matter–wave optics.

Generation of Coherent Trimers from Bose-Condensed Atoms via a Generalized Stimulated Raman Adiabatic Passage

We propose to use a generalized technique of stimulated Raman adiabatic passage to create an atom–molecule dark state that permits the enhanced coherent creation of triatomic molecules in a repulsive atomic Bose–Einstein condensate. As an interesting comparison, the similar cases of creating heteronuclear (bosonic or fermionic) trimers are also briefly discussed.

Macroscopic Atom-Molecule Dark State and Its Collective Excitations in Fermionic Systems

We show that a robust macroscopic atom-molecule dark state can exist in fermionic systems, which represents a coherent superposition between the ground molecular Bose-Einstein condensates and the atomic BCS paired state. We take advantage of the tunability offered by external laser fields, and explore this superposition for demonstrating coherent oscillations between ground molecules and atom pairs. We interpret the oscillation frequencies in terms of the collective excitations of the dark state.

Coherent Atom-Trimer Conversion in a Repulsive Bose-Einstein Condensate

We show that the use of a generalized atom-molecule dark state permits the enhanced coherent creation of triatomic molecules in a repulsive atomic Bose-Einstein condensate, with further enhancement being possible in the case of heteronuclear trimers via the constructive interference between two chemical reaction channels.

Adiabatic theorem for a condensate system in an atom-molecule dark state

We consider the adiabatic evolution of an atom-molecule dark state in a collisional two-color Raman photoassociation condensate system. By linking nonadiabaticity with the population growth in the collective excitations of the dark state, we develop an adiabatic theorem where we have consistently addressed the issues related to the Goldstone mode and the biorthonormality of the collective modes. We apply this theorem to specific examples to demonstrate its use in designing pulses that can optimize the yield of ground molecule production in the stimulated Raman adiabatic passage process.