Showing papers by "Robin Côté published in 2017"

Synthesis of mixed hypermetallic oxide BaOCa+ from laser-cooled reagents in an atom-ion hybrid trap

Abstract: Hypermetallic alkaline earth (M) oxides of formula MOM have been studied under plasma conditions that preclude insight into their formation mechanism. We present here the application of emerging techniques in ultracold physics to the synthesis of a mixed hypermetallic oxide, BaOCa+. These methods, augmented by high-level electronic structure calculations, permit detailed investigation of the bonding and structure as well as the mechanism of its formation via the barrierless reaction of Ca (3PJ) with BaOCH3+. Further investigations of the reaction kinetics as a function of collision energy over the range 0.005 kelvin (K) to 30 K and of individual Ca fine-structure levels compare favorably with calculations based on long-range capture theory.

Charge transfer in ultracold gases via Feshbach resonances

Abstract: We investigate the prospects of using magnetic Feshbach resonance to control charge exchange in ultracold collisions of heteroisotopic combinations of atoms and ions of the same element. The proposed treatment, readily applicable to alkali or alkaline-earth metals, is illustrated on cold collisions of $^{9}\mathrm{Be}^{+}$ and $^{10}\mathrm{Be}$. Feshbach resonances are characterized by quantum scattering calculations in a coupled-channel formalism that includes non-Born-Oppenheimer terms originating from the nuclear kinetic operator. Near a resonance predicted at 322 G, we find the charge exchange rate coefficient to rise from practically zero to values greater than ${10}^{\ensuremath{-}12}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{3}$/s. Our results suggest controllable charge exchange processes between different isotopes of suitable atom-ion pairs, with potential applications to quantum systems engineered to study charge diffusion in trapped cold atom-ion mixtures and emulate many-body physics.

Synthesis of mixed hypermetallic oxide BaOCa$^+$ from laser-cooled reagents in an atom-ion hybrid trap

Abstract: Hypermetallic alkaline earth (M) oxides of formula MOM have been studied under plasma conditions that preclude insight into their formation mechanism. We present here the application of emerging techniques in ultracold physics to the synthesis of a mixed hypermetallic oxide, BaOCa$^+$. These methods, augmented by high-level electronic structure calculations, permit detailed investigation of the bonding and structure, as well as the mechanism of its formation via the barrierless reaction of Ca $(^3P_J)$ with BaOCH$_{3}^+$. Further investigations of the reaction kinetics as a function of collision energy over the range 0.005 K to 30 K and of individual Ca fine-structure levels compare favorably with calculations based on long-range capture theory.

Molecular hydrogen: a benchmark system for near threshold resonances in high partial waves

Abstract: Benchmark reactions involving molecular hydrogen, such as H2 + D or H2 + Cl, provide the ideal platforms to investigate the effect of near threshold resonances (NTR) on scattering processes. Due to the small reduced mass of such systems, shape resonances in certain partial waves can provide features at scattering energies up to a few kelvin, achievable in current experiments. We explore the effects of NTRs on elastic and inelastic scattering for various partial waves l (in the case of H2 + Cl for s-wave and H2 + D for p-wave scattering) and find that NTRs lead to a different energy scaling of the cross sections as compared to the well known Wigner threshold regime. We give a theoretical analysis based on Jost functions, and we explore the NTR effects for higher partial waves using a simple model that incorporates the key ingredients of coupled-channel scattering problems. The effect of long-range interactions is also discussed, with special attention paid to the appearance of an effective Wigner regime for elastic scattering in certain partial waves.

Heteroisotopic Feshbach resonances in collisions of cold Ca and Ca

Abstract: Synopsis We investigate ultracold collisions of heteroisotopic pairs of Ca with Ca+ mediated by an external magnetic field. Based on the nuclear spin of Ca, namely I = 7/2 for 43Ca and I = 0 for other isotopes, we identify different scattering dynamics and characterize magnetic Feshbach resonances in 43Ca+43Ca+ and 43Ca+(40,42)Ca+ collisions. Our results suggest that interisotopic Feshbach resonances could be used to control charge-exchange in ultracold atom-ion mixtures of Ca and its ion.