Formation of Ultracold Molecules by Merging Optical Tweezers.

We demonstrate the formation of a single RbCs molecule during the merging of two optical tweezers, one containing a single Rb atom and the other a single Cs atom. Both atoms are initially predominantly in the motional ground states of their respective tweezers. We confirm molecule formation and establish the state of the molecule formed by measuring its binding energy. We find that the probability of molecule formation can be controlled by tuning the confinement of the traps during the merging process, in good agreement with coupled-channel calculations. We show that the conversion efficiency from atoms to molecules using this technique is comparable to magnetoassociation.

Production of Ultracold 87 Rb133 Cs in the Absolute Ground State: Complete Characterisation of the Stimulated Raman Adiabatic Passage Transfer.

We present the production of ultracold 87 RbCs molecules in the electronic, rovibrational and hyperfine ground state, using stimulated Raman adiabatic passage to transfer the molecules from a weakly bound Feshbach state. We measure one-way transfer efficiencies of 92(1)% and fully characterise the strengths and linewidths of the transitions used. We model the transfer, including a Monte Carlo simulation of the laser noise, and find this matches well with both the transfer efficiency and our previous measurements of the laser linewidth and frequency stability.

Ultracold dense samples of dipolar RbCs molecules in the rovibrational and hyperfine ground state.

We produce ultracold dense trapped samples of ^{87}Rb^{133}Cs molecules in their rovibrational ground state, with full nuclear hyperfine state control, by stimulated Raman adiabatic passage (STIRAP) with efficiencies of 90%. We observe the onset of hyperfine-changing collisions when the magnetic field is ramped so that the molecules are no longer in the hyperfine ground state. A strong quadratic shift of the transition frequencies as a function of applied electric field shows the strongly dipolar character of the RbCs ground-state molecule. Our results open up the prospect of realizing stable bosonic dipolar quantum gases with ultracold molecules.

Creation of ultracold

We report the creation of a sample of over 1000 ultracold ^{87}Rb^{133}Cs molecules in the lowest rovibrational ground state, from an atomic mixture of ^{87}Rb and ^{133}Cs, by magnetoassociation on an interspecies Feshbach resonance followed by stimulated Raman adiabatic passage (STIRAP). We measure the binding energy of the RbCs molecule to be hc×3811.576(1) cm^{-1} and the |v^{''}=0,J^{''}=0⟩ to |v^{''}=0,J^{''}=2⟩ splitting to be h×2940.09(6) MHz. Stark spectroscopy of the rovibrational ground state yields an electric dipole moment of 1.225(3)(8) D, where the values in parentheses are the statistical and systematic uncertainties, respectively. We can access a space-fixed dipole moment of 0.355(2)(4) D, which is substantially higher than in previous work.

Generating mesoscopic Bell states via collisions of distinguishable quantum bright solitons.

We investigate numerically the collisions of two distinguishable quantum matter-wave bright solitons in a one-dimensional harmonic trap. We show that such collisions can be used to generate mesoscopic Bell states that can reliably be distinguished from statistical mixtures. Calculation of the relevant s-wave scattering lengths predicts that such states could potentially be realized in quantum-degenerate mixtures of 85Rb and 133Cs. In addition to fully quantum simulations for two distinguishable two-particle solitons, we use a mean-field description supplemented by a stochastic treatment of quantum fluctuations in the soliton's center of mass: we demonstrate the validity of this approach by comparison to a mathematically rigorous effective potential treatment of the quantum many-particle problem.

TDDFT diagnostic testing and functional assessment for triazene chromophores.

A simple diagnostic test based on orbital overlap [M. J. G. Peach et al., J. Chem. Phys., 2008, 128, 044118] may be used to help judge the reliability of excitation energies in time-dependent density functional theory (TDDFT) when using generalized gradient approximation (GGA) and hybrid functionals. Orbital plots are used to illustrate the test for a model tripeptide and for 4-(N,N-dimethylamino)benzonitrile, which are representative of systems containing low- and high-overlap charge-transfer excitations. The scheme is then applied to a series of triazene chromophores in solvent, highlighting the relationship between overlap and oscillator strength and its implications for theoretical absorption spectra. No low-overlap excitations are observed with a hybrid functional; a single one is identified using a GGA. To assess the diagnostic test and to judge functional performance, gas phase triazene TDDFT excitations are compared with correlated ab initio values. The diagnostic test correctly identifies two low-overlap problematic GGA excitations. However, it does not identify another problematic excitation where the electron is excited to a spatially extended orbital, which necessarily has reasonable overlap with the occupied orbital; an improved diagnostic quantity is required for such cases. The best agreement between TDDFT and correlated ab initio excitations is obtained using a Coulomb-attenuated functional; the errors are significantly smaller than from the GGA and hybrid functionals. The study provides further support for the high quality excitations from Coulomb-attenuated functionals, negating the need for diagnostic tests.

Efficacy of toltrazuril (Baycox 5% suspension) in natural infections with pathogenic Eimeria spp. in housed lambs.

A field study was conducted to evaluate the effect of a single oral treatment with 20 mg/kg body weight (BW) of toltrazuril (Baycox 5% suspension)--TOL--in comparison to a single oral treatment with 1 mg/kg BW of diclazuril (Vecoxan suspension orale, 2.5 mg/ml)--DIC--and an untreated control group (CTRL) on naturally acquired Eimeria infections in lambs. On a French sheep farm with a known history of coccidiosis, 75 housed lambs aged 10-14 days were randomised and allocated to one of three groups. During an observation period of 60 days after treatment, clinical (faecal consistency, BW) and parasitological parameters (oocyst excretion) were evaluated. Excretion in the negative control group started 3 days after treatment and peaked on the 31st day with a prevalence of 80%. Animals were predominantly infected with Eimeria ovinoidalis. Treatment with toltrazuril, but not with diclazuril, resulted in significantly reduced numbers of excreting animals. The number of excretion days and the average oocyst excretion decreased significantly in both the TOL and the DIC groups compared to the CTRL, with the TOL group showing significantly fewer excretion days and excretion intensities than the DIC group. Changes in the faecal consistency were moderate throughout the study and not significantly different between the groups. Daily weight gains were higher in the TOL group compared to the DIC and CTRL groups which did not differ. This study demonstrates the good efficacy of toltrazuril administered orally to lambs in the prepatent period in subclinical natural Eimeria infections in housed lambs.

Comparative study of the photopic spectral sensitivity of domestic ducks (Anas platyrhynchos domesticus), turkeys (Meleagris gallopavo gallopavo) and humans.

1. The photopic spectral sensitivity of domestic ducks and turkeys was determined using an operant psychophysical technique. Spectral sensitivity was determined over a range of specified wavelengths, including UVA, between 326 < lambda < 694 nm and the results were directly compared with human spectral sensitivity measured under similar experimental conditions. 2. Domestic ducks and turkeys had similar spectral sensitivities to each other, and could perceive UVA radiation, although turkeys were more sensitive to UVA than ducks. For both species, peak sensitivity was between 544 < lambda < 577 nm, with reduced sensitivity at lambda = 508 and 600 nm. Both ducks and turkeys had a very different and broader range of spectral sensitivity than the human subjects tested. 3. Spectral sensitivity and UVA perception in these avian species are discussed in relation to their visual ecology and the mechanisms controlling neural processing of colour information.