Ticijana Ban

Predictions for the observation of KRb spectra under cold conditions

Quantum-mechanical simulations of the excitation spectra of KRb from the lowest vibrational level of the lowest triplet and singlet electronic states have been performed using recently calculated interaction potential curves and corresponding transition dipole moments. The obtained spectra can be used for a comparison with experimental absorption spectra of KRb molecules produced in their vibronic ground state or attached to cold helium droplets. In addition, we compare the semiclassically simulated spectra with absorption measurements in dense K–Rb vapour at high temperatures, which helped us to identify three diffuse bands as 1 3 � + –3 3 � ,1 3 � + –4 3 � and 1 1 � + –4 1 � + transitions. The first may be observable in an excitation spectrum of KRb dimer formed on cold helium droplets.

Photoassociation of cesium atoms into the double minimum Cs231Σu+ state

Abstract We have observed the transition from the free colliding pair of cesium atoms into the outer well of the double minimum Cs 2 3 1 Σ u + state. This photoassociation process takes place in a cesium vapor consisting predominantly of atoms, in which dimers have been about 85% thermally dissociated. Excellent agreement with quasiclassical simulations was found. We discuss the possibility of using a double minimum Cs 2 3 1 Σ u + state for the formation of ultracold Cs 2 X 1 Σ g + molecules.

Pure long-range ion-pair Cs2 molecules

Abstract We performed absorption measurements in dense cesium vapor, around the Cs second principal series lines (6s→7p). Three satellite bands peaking at 454.3, 459.1 and 471.6 nm are found. New ab initio Cs2 potential curves calculated with the inclusion of the spin–orbit interaction are used for the identification and simulation of the observed satellite bands. The 454.3 and 459.1 nm satellite bands stem from avoided crossings of long-range ion-pair potential curves with long-range covalent potential curves associated with various asymptotes. Semiclassical spectral simulations of these ion-pair satellite bands show satisfactory agreement with measured spectra.

Mapping of the Optical Frequency Comb to the Atom Velocity Comb

We present the experimental and theoretical study of the resonant excitation of rubidium and cesium atoms with fs pulse train in the conditions when the pulse repetition period is shorter than the atomic relaxation time. Velocity selective optical pumping of the ground state hyperfine levels and velocity comb‐like excited state hyperfine level populations is demonstrated. Both effects are a direct consequence of the fs pulse train excitation considered in the frequency domain. A simple experimental apparatus was employed to develop a modified direct frequency comb spectroscopy which uses a fixed frequency comb for the 85,87Rb 5s 2S1/2 → 5s 2P1/2,3/2 and 133Cs 6s 2S1/2 → 6p 2P1/2,3/2 excitation, and a weak cw scanning probe laser at 780 and 852 nm for Rb and Cs ground levels population monitoring.

Synthetic Lorentz force in classical atomic gases via Doppler effect and radiation pressure

We theoretically predict synthetic Lorentz force for classical (cold) atomic gases, which is based on the Doppler effect and radiation pressure. A fai

Cancellation of the coherent accumulation in rubidium atoms excited by a train of femtosecond pulses

We investigated the coherence accumulation in Rb atoms excited by a train of femtosecond pulses. The coherence accumulation results in the velocity selective optical pumping of Rb hyperfine levels, observed by a cw probe laser. The effects of the pulse train excitation on the cw probe laser transmission were investigated, depending on the probe laser power. We observed the probe laser absorption increase in the strong probe case, followed by the reduction of the modulations in the probe laser absorption. Results show that accumulation of population and coherence can be effectively reduced and eventually destroyed by increasing the cw laser intensity. A strong cw laser can therefore serve as a switch from the pulse-train to pulse-by-pulse type of interaction of Rb atoms with the fs laser. We developed a density-matrix based theoretical model of the eight-level Rb atoms interacting with the fs and cw laser fields, and present agreement with the experimental results.

Absorption spectrum of Na–K–He mixture: experiment and theory

We present experimental and theoretical studies of the absorption spectrum of Na–K–He mixture. Semiclassical spectral simulations in the 400–850 nm wavelength range were performed, on the basis of available interaction potential curves for Na2, K2, NaK, NaHe and KHe molecules. Calculated absorption spectra were analysed and compared to the experimental absorption spectrum of Na–K–He mixture generated in a gravitational heat pipe oven.

LiH emission spectrum from the glow discharge in a heat-pipe oven

We investigated emission spectrum of LiH molecules from an electric discharge in a heat-pipe oven. The optimal conditions for the most intense LiH emission regarding the vapour pressures of helium, hydrogen and lithium were found to be 2.5 Torr, 8.5 Torr and 0.9 mTorr, respectively. The important role of helium gas in increasing the LiH emission intensity is described. The number density of the lithium atoms in the first excited state, Li(2p) and the LiH emission, was measured for different hydrogen pressures and currents through the discharge. We found that one part of the LiH molecules formed in the discharge is created in chemical quenching of excited lithium atoms by H2 . We performed the theoretical simulations for observed LiH A 1 + -X 1 + emission band. The rotational temperature and the population distribution of vibrational levels in the LiH A 1 + state were determined. We also describe the search for emission from the LiH C 1 + electronic state in the spectrum, which at present is unsuccessful.

Constriction in lithium glow discharges in a heat-pipe oven

Abstract The electric discharge was established in a modified crossed heat-pipe oven filled with lithium. The discharge was spectroscopically studied for different lithium vapor pressures. Constriction of the positive column in the lithium vapor discharge was observed and the discharge diameter was measured as a function of lithium vapor pressure. The rich bound–bound emission molecular spectra of A 1 Σ + u →X 1 Σ + g and B 1 Π u →X 1 Σ + g systems of the lithium dimer were observed in lithium-rare gas discharges and correlated with the onset of the discharge constriction.

Experimental Demonstration of a Synthetic Lorentz Force by Using Radiation Pressure

Synthetic magnetism in cold atomic gases opened the doors to many exciting novel physical systems and phenomena. Ubiquitous are the methods used for the creation of synthetic magnetic fields. They include rapidly rotating Bose-Einstein condensates employing the analogy between the Coriolis and the Lorentz force, and laser-atom interactions employing the analogy between the Berry phase and the Aharonov-Bohm phase. Interestingly, radiation pressure - being one of the most common forces induced by light - has not yet been used for synthetic magnetism. We experimentally demonstrate a synthetic Lorentz force, based on the radiation pressure and the Doppler effect, by observing the centre-of-mass motion of a cold atomic cloud. The force is perpendicular to the velocity of the cold atomic cloud, and zero for the cloud at rest. Our novel concept is straightforward to implement in a large volume, for a broad range of velocities, and can be extended to different geometries.