Reply to "Comment on 'Stimulated Raman adiabatic passage from an atomic to a molecular Bose-Einstein condensate'"

In the Comment by M. Mackie \textit{et al.} [arXiv: physics/0212111 v.4], the authors suggest that the molecular conversion efficiency in atom-molecule STIRAP can be improved by lowering the initial atomic density, which in turn requires longer pulse durations to maintain adiabaticity. Apart from the fact that the mean-field approximation becomes questionable at low densities, we point out that a low-density strategy with longer pulses has several problems. It generally requires higher pulse energies, and increases radiative losses. We also show that even within the approximations used in the Comment, their example leads to no efficiency improvement compared to our high-density case. In a more careful analysis including radiative losses neglected in the Comment, the proposed strategy gives almost no conversion owing to the longer pulse durations required.Comment: Accepted for publication in Phys. Rev.

Polyatomic Molecules Formed with a Rydberg Atom in an Ultracold Environment

We investigate properties of ultralong-range polyatomic molecules formed with a Rb Rydberg atom and several ground-state atoms whose distance from the Rydberg atom is of the order of n^2a_0, where n is the principle quantum number of the Rydberg electron. In particular, we put emphasis on the splitting of the energy levels, and elucidate the nature of the splitting via the construction of symmetry-adapted orbitals.Comment: 2 columns, 7 pages, 7 figures. Final verso

Quantum instabilities in the system of identical bosons

The quantum instability of the mean-field theory for identical bosons is shown to be described by an appropriate Bogoliubov transformation. A connection between the quantum and classical linear stability theories is indicated. It is argued that the instability rate in a system of identical bosons must be strongly affected by the nonlinear terms (interactions). In the case of the repulsive interactions or strong attractive interactions the instability rate is suppressed. On the other hand, a weak attraction significantly enhances the instability rate. The results can have applications in the field of Bose-Einstein condensates of dilute quantum gases.Comment: 12 pages. 2 figures. To appear in Physics Letters

Михайло Грушевський в історії України (Mikhailo Hrushevs’kyi in history of Ukraine)

У статті характеризується роль Михайла Грушевського у розвитку історичної науки та політичному житті України. Наголошується на внеску вченого у розбудову українських наукових інституцій: Наукового товариства ім. Шевченка, Академії наук тощо (The article characterized the role of Mykhailo Hrushevsky in the development of historical scholarship and political life of Ukraine. Emphasis is on scientific contributions to the development of Ukrainian research institutions: Shevchenko Scientific Society , Academy of Sciences of others

Quantum computations with atoms in optical lattices: marker qubits and molecular interactions

We develop a scheme for quantum computation with neutral atoms, based on the concept of "marker" atoms, i.e., auxiliary atoms that can be efficiently transported in state-independent periodic external traps to operate quantum gates between physically distant qubits. This allows for relaxing a number of experimental constraints for quantum computation with neutral atoms in microscopic potential, including single-atom laser addressability. We discuss the advantages of this approach in a concrete physical scenario involving molecular interactions.Comment: 15 pages, 14 figure

Quantum Dynamics of Atom-molecule BECs in a Double-Well Potential

We investigate the dynamics of two-component Bose-Josephson junction composed of atom-molecule BECs. Within the semiclassical approximation, the multi-degree of freedom of this system permits chaotic dynamics, which does not occur in single-component Bose-Josephson junctions. By investigating the level statistics of the energy spectra using the exact diagonalization method, we evaluate whether the dynamics of the system is periodic or non-periodic within the semiclassical approximation. Additionally, we compare the semiclassical and full-quantum dynamics.Comment: to appear in JLTP - QFS 200

Boson-like quantum dynamics of association in ultracold Fermi gases

We study the collective association dynamics of a cold Fermi gas of $2N$ atoms in $M$ atomic modes into a single molecular bosonic mode. The many-body fermionic problem for $2^M$ amplitudes is effectively reduced to a dynamical system of $\min\{N,M\}+1$ amplitudes, making the solution no more complex than the solution of a two-mode Bose-Einstein condensate and allowing realistic calculations with up to $10^4$ particles. The many-body dynamics is shown to be formally similar to the dynamics of the bosonic system under the mapping of boson particles to fermion holes, producing collective enhancement effects due to many-particle constructive interference. Dissociation rates are shown to enhance as the number of particles whereas association rates are enhanced as the number of holes, leading to boson-like collective behavior.Comment: 5 pages, 2 figures, critical typo in Eq. (13) correcte

Controlling two-species Mott-insulator phses in an optical lattice to form an array of dipolar molecules

We consider the transfer of a two-species Bose-Einstein condensate into an optical lattice with a density such that that a Mott-insulator state with one atom per species per lattice site is obtained in the deep lattice regime. Depending on collision parameters the result could be either a `mixed' or a `separated' Mott-insulator phase. Such a `mixed' two-species insulator could then be photo-associated into an array of dipolar molecules suitable for quantum computation or the formation of a dipolar molecular condensate. For the case of a $^{87}$Rb-$^{41}$K two-species BEC, however, the large inter-species scattering length makes obtaining the desired `mixed' Mott insulator phase difficult. To overcome this difficulty we investigate the effect of varying the lattice frequency on the mean-field interaction and find a favorable parameter regime under which a lattice of dipolar molecules could be generated