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Makarov, O. P.; Côté, Robin; Michels, H. H.; Smith, William Hayden

doi:10.1103/physreva.67.042705

Cited by 94 publications

(129 citation statements)

References 18 publications

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“…We adapt MQDT to the atom-ion realm, utilizing the analytical solutions for the r −4 asymptotic potential [9,11] and applying the frame transformation [10,12] at short distances to reduce the number of quantum defect parameters in the model. We verify the model predictions by comparing to our own numerical close-coupled calculations, taking 40 Ca + − 23 Na [13] as a reference system.…”

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confidence: 98%

“…[13], both elastic and inelastic quantum cross sections appear to be strongly affected by the presence of shape resonances up to mK regime; see Fig. 1.…”

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confidence: 99%

“…1 shows the total rate vσ tr of inelastic A 1 Σ + → X 1 Σ + collisions associated with radiative charge transfer (see [13] for details). The numerical results (first three entries in the legend) have been obtained in the distorted-wave Born approximation by summing contributions from all free-free and free-bound transitions [20].…”

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confidence: 99%

“…We now apply our model to a system of 40 Ca + and 23 Na for which the long-range parameter C 4 = 81.35 a.u. and the short-range ab-initio potential curves are ap-proximately known [13]. The close-coupled Schrödinger equation (1) is solved both within our MQDT approach and exactly using standard numerical methods.…”

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Quantum theory of ultracold atom-ion collisions

et al. 2009

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We study atom-ion scattering in the ultracold regime. To this aim, an analytical model based on the multichannel quantum defect formalism is developed and compared to close-coupled numerical calculations. We investigate the occurrence of magnetic Feshbach resonances focusing on the specific 40 Ca + + Na system. The presence of several resonances at experimentally accessible magnetic fields should allow the atom-ion interaction to be precisely tuned. A fully quantum-mechanical study of charge exchange processes shows that charge-exchange rates should remain small even in the presence of resonance effects. Most of our results can be cast in a system-independent form and are important for the realization of the charge-neutral ultracold systems.Advances in trapping, cooling, manipulation and readout of single atoms and ions have led over recent years to a range of fundamental as well as applied investigations on the quantum properties of such systems. Nowadays, an increasing number of experimental groups worldwide are starting experiments with combined charged-neutral systems in various configurations [1]. While the theory of atom-ion collisions is well established for high collision energies [2,3], a theoretical description in the ultracold domain is still largely missing.This letter presents the first study of magnetic Feshbach resonances and the first fully quantum study of the radiative charge exchange process for ultracold atomion systems that includes effects of Feshbach and shape resonances. Here we consider only two-body collisions in free space, a necessary prelude to further studies incorporating effects of ion micromotion or trap confinement. We develop a reliable yet manageable effective model of atom-ion collisions by applying multichannel quantum defect theory (MQDT) [4,5,6] based on the long range ion-induced-dipole potential that varies as r −4 at large ion-atom distance r [7,8]. This powerful tool has proven effective as a few-parameter approach for describing scattering and bound states in electron-ion core [4], electron-atom [9] and neutral atom systems [10]. Although the literature on the subject is rich, here we discuss some details of MQDT illustrating how it works in the ultracold domain, so we can reveal the new and interesting ultracold ion-atom physics. We adapt MQDT to the atom-ion realm, utilizing the analytical solutions for the r −4 asymptotic potential [9,11] and applying the frame transformation [10,12] at short distances to reduce the number of quantum defect parameters in the model. We verify the model predictions by comparing to our own numerical close-coupled calculations, taking 40 Ca + − 23 Na [13] as a reference system.We describe the S-state atom and S-state ion collisions with the close-coupled radial Schrödinger equationHere, µ = m i m a /(m i + m a ) denotes the reduced mass, W(r) is the interaction matrix, and F(r) is the matrix of radial solutions. The wave function for N scattering channels reads Ψ i (r) = N j=1 A j Y j (r)F ij (r)/r where Y j (r) denotes the angular par...

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confidence: 98%

“…[13], both elastic and inelastic quantum cross sections appear to be strongly affected by the presence of shape resonances up to mK regime; see Fig. 1.…”

mentioning

confidence: 99%

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confidence: 99%

mentioning

confidence: 99%

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Quantum theory of ultracold atom-ion collisions

et al. 2009

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“…In a recent paper Makarov et al [13] performed ab initio and dynamical calculations on the (CaNa) + molecular ion. The results of these calculations suggest that the milliKelvin regime of collisional cooling of calcium ions by sodium atoms is very favorable, with the rate coefficient for charge transfer from the Na atom to the Ca + ion several orders of magnitude smaller than the rate for elastic and spin-exchange collisions.…”

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Sympathetic cooling of the Ba+ion by collisions with ultracold Rb atoms: Theoretical prospects

et al. 2011

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State-of-the-art ab initio techniques have been applied to compute the potential energy curves of the (BaRb) + molecular ion in the Born-Oppenheimer approximation for the singlet and triplet states dissociating into the ground state 1 S Rb + ion and the Ba atom in the ground 1 S state, the lowest singlet or triplet D excited states, and for the singlet and triplet states dissociating into the ground state 2 S Rb atom and the ground state 2 S Ba + ion. The ground state potential energy was obtained with the coupled cluster method restricted to single, double, and nonperturbative triple excitations. The first triplet states in the Σ, Π, and ∆ symmetries were computed with the restricted open-shell coupled cluster method restricted to single, double, and nonperturbative triple excitations. All other excited state potential energy curves were computed using the equation of motion approach within the coupled-cluster singles, doubles, and linear triples framework.The long-range coefficients describing the electrostatic, induction, and dispersion interactions at large interatomic distances are also reported. The electric transition dipole moments governing the X 1 Σ → 1 Σ, 1 Π have been obtained as the first residue of the polarization propagator computed with the linear response coupled-cluster method restricted to single and double excitations. Nonadiabatic radial and angular coupling matrix elements, as well as the spin-orbit coupling matrix elements have been evaluated using the multireference configuration interaction method restricted to single and double excitations with a large active space. With these couplings, the spin-orbit coupled (relativistic) potential energy curves for the 0 + and 1 states relevant for the running experiments have been obtained. Finally, relativistic transition moments and nonadiabatic coupling matrix elements were obtained from the nonrelativistic results and spin-orbit eigenvectors. The electronic structure input has been employed in the single channel scattering calculations of the collisional cross sections between the Ba + ion and Rb atom. Both nonrelativistic and relativistic potentials were used in these calculations. Our results show that the inelastic cross section corresponding to the charge transfer from the Rb atom to the Ba + ion is much smaller than the elastic one over a wide range of energies up to 1 mK. This suggests that sympathetic cooling of the Ba + ion by collisions with ultracold Rb atoms should be possible.2

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Operation of a Microfabricated Planar Ion‐Trap for Studies of a Yb⁺–Rb Hybrid Quantum System

Bahrami

Müller

Drechsler

et al. 2019

Physica Status Solidi (b)

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In order to study interactions of atomic ions with ultracold neutral atoms, it is important to have sub‐µm control over positioning ion crystals. Serving for this purpose, a microfabricated planar ion trap featuring 21 DC electrodes is introduced. The ion trap is controlled by a home‐made FPGA voltage source providing independently variable voltages to each of the DC electrodes. To assure stable positioning of ion crystals with respect to trapped neutral atoms, the authors integrate into the overall design a compact mirror magneto optical chip trap (mMOT) for cooling and confining neutral 87Rb atoms. The trapped atoms will be transferred into an also integrated chip‐based Ioffe‐Pritchard trap potential formed by a Z‐shaped wire and an external bias magnetic field. The authors introduce the hybrid atom–ion chip, the microfabricated planar ion trap, and use trapped ion crystals to determine ion lifetimes, trap frequencies, positioning ions, and the accuracy of the compensation of micromotion.

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Radiative charge-transfer lifetime of the excited state of(NaCa)+

Cited by 94 publications

References 18 publications

Quantum theory of ultracold atom-ion collisions

Quantum theory of ultracold atom-ion collisions

Sympathetic cooling of the Ba+ion by collisions with ultracold Rb atoms: Theoretical prospects

Operation of a Microfabricated Planar Ion‐Trap for Studies of a Yb⁺–Rb Hybrid Quantum System

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Radiative charge-transfer lifetime of the excited state of(NaCa)+

Cited by 94 publications

References 18 publications

Quantum theory of ultracold atom-ion collisions

Quantum theory of ultracold atom-ion collisions

Sympathetic cooling of the Ba+ion by collisions with ultracold Rb atoms: Theoretical prospects

Operation of a Microfabricated Planar Ion‐Trap for Studies of a Yb+–Rb Hybrid Quantum System

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Operation of a Microfabricated Planar Ion‐Trap for Studies of a Yb⁺–Rb Hybrid Quantum System