Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Reaction stability and electric-field shielding in ultracold collisions of strongly dipolar NaBr and KBr molecules

Marc E. Segovia, Oscar N. Ventura

Published Jan 1, 2026• 0 citations
Publisher
DOI
10.2139/ssrn.7112174

Related papers

Shielding ultracold dipolar molecular collisions with electric fields

Goulven Quéméner, John L. Bohn

Bulletin of the American Physical Society•May 26, 2016•0 citations

A simple model to describe electric field shielding of two-body ultracold molecular collisions

Lucas Lassablière, Goulven Quéméner

Bulletin of the American Physical Society•Jun 2, 2021•0 citations

Ab Initio Investigation of Chemical Reaction Pathways in Ultracold NaBr and KBr Molecular Collisions: Diatomic Validation, Dissociation Energies, and the NaKBr2 Tetramer Intermediate

Marc E. Segovia, Oscar N. Ventura

Alkali bromides NaBr and KBr possess permanent electric dipole moments of approximately 9.1 and 10.5 D, among the largest of any diatomic molecule, making them exceptional candidates for dipolar quantum science and electric-field-controlled ultracold collisions. We report a systematic ab initio investigation of all two-body reaction channels for NaBr + NaBr, KBr + KBr, and NaBr + KBr collisions using CCSD(T)/aug-cc-pVQZ potential-energy curves validated against experimental spectroscopic constants, supplemented by phaseless auxiliary-field quantum Monte Carlo (ph-AFQMC) benchmarks. All bond-swap channels are endoergic by 38,000–43,000 cm−1 (109–122 kcal mol−1) and all atom-abstraction channels by 21,000–25,000 cm−1 (60–71 kcal mol−1), thermodynamically forbidding reactive product formation at ultracold collision energies. DLPNO-CCSD(T) approach potentials, validated against canonical CCSD(T), are purely attractive for all three collision pairs, with no entrance barriers. The NaBr + KBr system additionally supports a deep alternating NaKBr2 short-range complex (well depth −47.9 kcal mol−1 at the CCSD(T)/aug-cc-pVQZ level, −42.8 counterpoise-corrected; −50.3 ± 0.3 kcal mol−1 at the ph-AFQMC level), a rectangular rock-salt intermediate analogous to the M2X2 minimum characterized for calcium monofluoride (CaF + CaF) collisions. Owing to the large permanent dipoles, the isotropic long-range interaction is dominated by the rotational dispersion term, giving total C6 ≈ 4×107–1.3×108 a.u. and universal s-wave loss rates of ≈6–8 × 10−10 cm3 s−1, at or above the KRb value. Suppressing these losses requires electric-field shielding with the molecules prepared in their first rotationally excited state; the resonant mechanism is predicted to be highly effective, with critical fields of ≈1.6–3.4 kV cm−1, comparable to those for strongly dipolar bialkali molecules such as RbCs and within an order of magnitude of KRb (∼12 kV cm−1). These results establish alkali bromides as thermodynamically stable against exchange chemistry while identifying complex-mediated (“sticky”) loss and resonant electric-field shielding as the dominant processes governing ultracold NaBr and KBr collisions.

•Jun 16, 2026•0 citations

Shielding Σ 2 ultracold dipolar molecular collisions with electric fields

Goulven Quéméner, John L. Bohn

The prospects for shielding ultracold, paramagnetic, dipolar molecules from inelastic and chemical collisions are investigated. Molecules placed in their first rotationally excited states are found to exhibit effective long-range repulsion for applied electric fields above a certain critical value, as previously shown for nonparamagnetic molecules. This repulsion can safely allow the molecules to scatter while reducing the risk of inelastic or chemically reactive collisions. Several molecular species of $^{2}\mathrm{\ensuremath{\Sigma}}$ molecules of experimental interest---RbSr, SrF, BaF, and YO---are considered, and all are shown to exhibit orders of magnitude suppression in quenching rates in a sufficiently strong laboratory electric field. It is further shown that, for these molecules described by Hund's coupling case (b), electronic and nuclear spins play the role of spectator with respect to the shielding.

arXiv:1510.06601•Physical Review A•Jan 11, 2016•65 citations

Optical shielding of destructive chemical reactions between ultracold ground-state NaRb molecules

Andrea Orbán, Ting Xie, Maxence Lepers +3 more

Polar quantum gases represent promising platforms for studying many-body physics and strongly correlated systems with possible applications e.g. in quantum simulation or quantum computation. Due to their large permanent electric dipole moment polar molecules in electric field exhibit strong long-range anisotropic dipole-dipole interactions (DDIs). The creation and trapping of ultracold dipolar diatomic molecules of various species are feasible in many experimental groups nowadays. However long time trapping is still a challenge even in the case of the so called nonreactive molecules which are supposed to be immune against inelastic collisions in their absolute ground state [1] . Various hypothesis have been invoked to explain the possible mechanisms behind the trapping loss, however the check of their pertinence is not trivial since the final products can not be easily detected [2] . To overcome the loss processes we propose the suppression of inelastic collisions between molecules using optical shielding (OS). OS relies on the modification of long-range interactions between ground-state and excited molecules by laser light. The first experimental proof of OS process was demonstrated in case of the collision between identical ultracold alkali-metal atoms [3] .

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)•Jun 21, 2021•1 citation

Ultracold dipolar collisions of KRb molecules in a 2D confined geometry

Goulven Quéméner, John L. Bohn

Bulletin of the American Physical Society•May 28, 2010•0 citations
Alkali bromides NaBr and KBr possess permanent electric dipole moments of approximately 9.1 and 10.5 D, among the largest of any diatomic molecule, making them exceptional candidates for dipolar quantum science and electric-field-controlled ultracold collisions. We report a systematic ab initio investigation of all two-body reaction channels for NaBr + NaBr, KBr + KBr, and NaBr + KBr collisions using CCSD(T)/aug-cc-pVQZ potential-energy curves validated against experimental spectroscopic constants, supplemented by phaseless auxiliary-field quantum Monte Carlo (ph-AFQMC) benchmarks. All bond-swap channels are endoergic by 38,000–43,000 cm−1 (109–122 kcal mol−1) and all atom-abstraction channels by 21,000–25,000 cm−1 (60–71 kcal mol−1), thermodynamically forbidding reactive product formation at ultracold collision energies. DLPNO-CCSD(T) approach potentials, validated against canonical CCSD(T), are purely attractive for all three collision pairs, with no entrance barriers. The NaBr + KBr system additionally supports a deep alternating NaKBr2 short-range complex (well depth −47.9 kcal mol−1 at the CCSD(T)/aug-cc-pVQZ level, −42.8 counterpoise-corrected; −50.3 ± 0.3 kcal mol−1 at the ph-AFQMC level), a rectangular rock-salt intermediate analogous to the M2X2 minimum characterized for calcium monofluoride (CaF + CaF) collisions. Owing to the large permanent dipoles, the isotropic long-range interaction is dominated by the rotational dispersion term, giving total C6 ≈ 4×107–1.3×108 a.u. and universal s-wave loss rates of ≈6–8 × 10−10 cm3 s−1, at or above the KRb value. Suppressing these losses requires electric-field shielding with the molecules prepared in their first rotationally excited state; the resonant mechanism is predicted to be highly effective, with critical fields of ≈1.6–3.4 kV cm−1, comparable to those for strongly dipolar bialkali molecules such as RbCs and within an order of magnitude of KRb (∼12 kV cm−1). These results establish alkali bromides as thermodynamically stable against exchange chemistry while identifying complex-mediated (“sticky”) loss and resonant electric-field shielding as the dominant processes governing ultracold NaBr and KBr collisions.
The prospects for shielding ultracold, paramagnetic, dipolar molecules from inelastic and chemical collisions are investigated. Molecules placed in their first rotationally excited states are found to exhibit effective long-range repulsion for applied electric fields above a certain critical value, as previously shown for nonparamagnetic molecules. This repulsion can safely allow the molecules to scatter while reducing the risk of inelastic or chemically reactive collisions. Several molecular species of $^{2}\mathrm{\ensuremath{\Sigma}}$ molecules of experimental interest---RbSr, SrF, BaF, and YO---are considered, and all are shown to exhibit orders of magnitude suppression in quenching rates in a sufficiently strong laboratory electric field. It is further shown that, for these molecules described by Hund's coupling case (b), electronic and nuclear spins play the role of spectator with respect to the shielding.
Polar quantum gases represent promising platforms for studying many-body physics and strongly correlated systems with possible applications e.g. in quantum simulation or quantum computation. Due to their large permanent electric dipole moment polar molecules in electric field exhibit strong long-range anisotropic dipole-dipole interactions (DDIs). The creation and trapping of ultracold dipolar diatomic molecules of various species are feasible in many experimental groups nowadays. However long time trapping is still a challenge even in the case of the so called nonreactive molecules which are supposed to be immune against inelastic collisions in their absolute ground state [1] . Various hypothesis have been invoked to explain the possible mechanisms behind the trapping loss, however the check of their pertinence is not trivial since the final products can not be easily detected [2] . To overcome the loss processes we propose the suppression of inelastic collisions between molecules using optical shielding (OS). OS relies on the modification of long-range interactions between ground-state and excited molecules by laser light. The first experimental proof of OS process was demonstrated in case of the collision between identical ultracold alkali-metal atoms [3] .