Production ofNaCa+molecular ions in the ground state from cold atom-ion mixtures by photoassociation via an intermediate state

Abstract

We present a theoretical analysis of optical pathways for formation of cold ground state (NaCa) + molecular ions via an intermediate state. The formation schemes are based on ab initio potential energy curves and transition dipole moments calculated using effective-core-potential methods of quantum chemistry. In the proposed approach, starting from a mixture of cold trapped Ca + ions immersed into an ultracold gas of Na atoms, (NaCa) + molecular ions are photoassociated in the excited E 1 Σ + electronic state and allowed to spontaneously decay either to the ground electronic state or an intermediate state from which the population is transferred to the ground state via an additional optical excitation. By analyzing all possible pathways, we find that the efficiency of a two-photon scheme, via either B 1 Σ + or C 1 Σ + potential, is sufficient to produce significant quantities of ground state (NaCa) + molecular ions. A single-step process results in lower formation rates that would require either a high density sample or a very intense photoassociation laser to be viable.

Cold hybrid ion-atom systems

“…where the expressions in round brackets are 3j symbols, 2S+1 L||Q 2(4) || 2S+1 L is the reduced matrix element of the quadrupole (hexadecapole) moment, and α 0 (iω) and α 2 (iω) are the scalar and tensor components of the dynamic electric dipole polarizability at imaginary frequency of the atom in the 2S+1 L state. The electronic structure data, including the potential energy curves for the ground and excited electronic states, transition electric dipole moments, and matrix elements of the spin-orbit coupling have been calculated for several ion-atom systems relevant for ongoing experimental efforts: (Na+Ca) + (Gacesa et al, 2016;Makarov et al, 2003), (Rb+Ba) + (Knecht et al, 2010;Krych et al, 2011), (Li/Na/K/Rb/Cs+Sr) + , (Rb+Ca) + (Belyaev et al, 2012;Tacconi et al, 2011), (Rb+Yb) + (Lamb et al, 2012;McLaughlin et al, 2014;Sayfutyarova et al, 2013), (Li+Yb) + da Silva Jr et al, 2015;Tomza et al, 2015), (Ca/Sr/Ba/Yb+Cr) + (Tomza, 2015), (Li+Be) + (Ghanmi et al, 2017), (Li+Mg) + (ElOualhazi and , (Li+Ca) + (Saito et al, 2017), (Li+Sr) + (Jellali et al, 2016), (Rb+Ca/Sr/Ba/Yb) + (da Silva Jr et al, 2015), (Na/Ka/Rb+Be) + (Ladjimi et al, 2018), (Li+Li) + (Bouchelaghem and Bouledroua, 2014;Bouzouita et al, 2006;Musia l et al, 2015), (Na+Na) + (Berriche, 2013;Bewicz et al, 2017), (K+K) + (Skupin et al, 2017), (Rb+Rb) + (Jraij et al, 2003;Jyothi et al, 2016), (Cs+Cs) + (Jamieson et al, 2009;Jraij et al, 2005), (Li+Na) + (Li et al, 2015;Musia l et al, 2018), (Li+K) + (Berriche et al, 2005;…”

“…Numerical calculations of Feshbach resonance spectra have been performed by (Gacesa and Côté, 2017;Idziaszek et al, 2011;Tomza, 2015;Tomza et al, 2015) for a number of ion-atom systems including Yb + +Li, which is the most promising in this respect from the experimental point of view due to the smallest reduced mass. Feshbach resonances were also investigated for collisions involving Cr atoms.…”

“…45 because they are governed by the same transition dipole moments. (Gacesa et al, 2016) studied theoretically the optical pathways for the formation of cold ground-state NaCa + molecular ions as schematically presented in Fig. 48.…”

“…48 Schematic representation of the optical pathways to produce NaCa + molecular ions in the electronic ground state. From(Gacesa et al, 2016).…”

Cold chemistry: a few-body perspective on impurity physics of a single ion in an ultracold bath

“…These laser sources are generally assumed to have a little impact on the dynamics of a single ion in a bath of ultracold atoms. However, it has been shown that the trapping lasers of a magneto-optical trap holding ultracold atoms may lead to an enhancement of the rate of charge-transfer reactions [9,20,32,93,94]. Therefore, laser sources may play a relevant role in the study of a charged impurity in a bath of ultracold atoms.…”