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.

Sounding Vessel Position From Adjustment by Variation of Parameters

For hydrographic surveys conducted by the U.S. Naval Oceanographic Office, the position of a sounding vessel is determined by applying the method of adjustment by variation of parameters. Three types of navigational aids are used: ranging, azimuthal, and hyperbolic. Given data from any combination of at least two navigational aids, a fix may be obtained using an iterative method, which applies successive adjustments to an approximate location and forces it to converge to the most probable position. The magnitude and direction of each adjustment is determined from a least squares solution that minimizes the residual differences between actual navigational observations and imaginary observations calculated as if the ship were at the approximate location

The influence of different soil types in the pesticide residue analysis method performance

Pesticide residues in soils cause increasing environmental problems. The underlying biological activity of herbicides from one cropping season to another could affect the productivity of the new crops. Agricultural practices also influence the herbicide level and their accumulation in soil. They interact with soil particles through absorption or adsorption by ionic interactions and other forces ruled by physicochemical properties such as Kow, Henry´s law constant, and Koc, as concentration dependent phenomena but soil texture and composition  play a decisive role in their environmental behavior. To understand the general effect, the residues concentrations have to be precisely known.  Although traditional pesticides such as organophosphates, pyerthorids and carbamates can be straightforward analysed in soils through general multirresidue methods, the determination of multiherbicide residues is a difficult task because soil is a complex and variable analytical matrix as different analyte/matrix interactions present. Herbicides are seldom applied alone but there are few methods reported capable of analysing high number of compounds. We studied the influence of 4 characteristics soils from Uruguay in 4 different methods for the residue analysis of 18 herbicides. Loam soils are the most common soils in Uruguay followed by clay ones and combinations of the two, with variable amounts of organic matter. The key step in this type of analysis is the extraction step. Seeking for a method usefull to analyze most of the soils types in Uruguay, we faced a systematic study using four different extraction procedures ( Methanol, Mixtures MeOH-Ethyl Acetate and Methanol-basic water). Nevertheless, in a first approach, we were not able to find a single method with aceptable performance for every soil under study. According to the type of soil, the best extraction solvent varied. The amount of organic matter played a role but also the texture of the soils was determinant for the method success. Finally, a two step extraction method gave the best results. The soil is firstly extracted with MeOH followed by a water extraction. The extracts are combined and analyzeed using LC-MS/MS. Herbicides could be determined at 0,1-1µg/Kg level. The method was succesfully applied to the herbicide residue analysis of more than 80 soil samples during three cropping seasons, where many pesticides were detected (Clomazone, Quinclorac, Benzosulfuron, Propanyl, Atrazine,Ametryn, among others )

Cavity induced modifications to the resonance fluorescence and probe absorption of a laser-dressed V atom

A cavity-modified master equation is derived for a coherently driven, V-type three-level atom coupled to a single-mode cavity in the bad cavity limit. We show that population inversion in both the bare and dressed-state bases may be achieved, originating from the enhancement of the atom-cavity interaction when the cavity is resonant with an atomic dressed-state transition. The atomic populations in the dressed state representation are analysed in terms of the cavity-modified transition rates. The atomic fluorescence spectrum and probe absorption spectrum also investigated, and it is found that the spectral profiles may be controlled by adjusting the cavity frequency. Peak suppression and line narrowing occur under appropriate conditions.Comment: 12 pages, 10 postscript figures, to be appeared in Phys. Rev.

Quantum Logic for Trapped Atoms via Molecular Hyperfine Interactions

We study the deterministic entanglement of a pair of neutral atoms trapped in an optical lattice by coupling to excited-state molecular hyperfine potentials. Information can be encoded in the ground-state hyperfine levels and processed by bringing atoms together pair-wise to perform quantum logical operations through induced electric dipole-dipole interactions. The possibility of executing both diagonal and exchange type entangling gates is demonstrated for two three-level atoms and a figure of merit is derived for the fidelity of entanglement. The fidelity for executing a CPHASE gate is calculated for two 87Rb atoms, including hyperfine structure and finite atomic localization. The main source of decoherence is spontaneous emission, which can be minimized for interaction times fast compared to the scattering rate and for sufficiently separated atomic wavepackets. Additionally, coherent couplings to states outside the logical basis can be constrained by the state dependent trapping potential.Comment: Submitted to Physical Review

The electron electric dipole moment enhancement factors of Rubidium and Caesium atoms

The enhancement factors of the electric dipole moment (EDM) of the ground states of two paramagnetic atoms; rubidium (Rb) and caesium (Cs) which are sensitive to the electron EDM are computed using the relativistic coupled-cluster theory and our results are compared with the available calculations and measurements. The possibility of improving the limit for the electron EDM using the results of our present work is pointed out.Comment: AISAMP7 Conference paper, Accepted in Journal of Physics: Conference Series: 200

Stimulated Raman adiabatic passage from an atomic to a molecular Bose-Einstein condensate

The process of stimulated Raman adiabatic passage (STIRAP) provides a possible route for the generation of a coherent molecular Bose-Einstein condensate (BEC) from an atomic BEC. We analyze this process in a three-dimensional mean-field theory, including atom-atom interactions and non-resonant intermediate levels. We find that the process is feasible, but at larger Rabi frequencies than anticipated from a crude single-mode lossless analysis, due to two-photon dephasing caused by the atomic interactions. We then identify optimal strategies in STIRAP allowing one to maintain high conversion efficiencies with smaller Rabi frequencies and under experimentally less demanding conditions.Comment: Final published versio

Mode structure and ray dynamics of a parabolic dome microcavity

We consider the wave and ray dynamics of the electromagnetic field in a parabolic dome microcavity. The structure of the fundamental s-wave involves a main lobe in which the electromagnetic field is confined around the focal point in an effective volume of the order of a cubic wavelength, while the modes with finite angular momentum have a structure that avoids the focal area and have correspondingly larger effective volume. The ray dynamics indicates that the fundamental s-wave is robust with respect to small geometrical deformations of the cavity, while the higher order modes are associated with ray chaos and short-lived. We discuss the incidence of these results on the modification of the spontaneous emission dynamics of an emitter placed in such a parabolic dome microcavity.Comment: 50 pages, 17 figure

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

Theoretical model for ultracold molecule formation via adaptive feedback control

We investigate pump-dump photoassociation of ultracold molecules with amplitude- and phase-modulated femtosecond laser pulses. For this purpose a perturbative model for the light-matter interaction is developed and combined with a genetic algorithm for adaptive feedback control of the laser pulse shapes. The model is applied to the formation of 85Rb2 molecules in a magneto-optical trap. We find for optimized pulse shapes an improvement for the formation of ground state molecules by more than a factor of 10 compared to unshaped pulses at the same pump-dump delay time, and by 40% compared to unshaped pulses at the respective optimal pump-dump delay time. Since our model yields directly the spectral amplitudes and phases of the optimized pulses, the results are directly applicable in pulse shaping experiments