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

arXiv:1808.07585 · Review of Scientific Instruments

High-resolution collision energy control through ion position modulation in atom-ion hybrid systems

Prateek Puri, Michael Mills, Elizabeth P. West, Christian Schneider, Eric R. Hudson

Published Aug 1, 2018• 9 citations
arXivHTMLPDF

Abstract

We demonstrate an ion shuttling technique for high-resolution control of atom-ion collision energy by translating an ion held within a radio-frequency trap through a magneto-optical atom trap. The technique is demonstrated both experimentally and through numerical simulations, with the experimental results indicating control of ion kinetic energies from 0.05 to 1 K with a fractional resolution of ∼10 and the simulations demonstrating that kinetic energy control up to 120 K with a maximum predicted resolution of ∼100 is possible, offering order-of-magnitude improvements over most alternative techniques. Finally, we perform a proof-of-principle chemistry experiment using this technique and outline how the method may be refined in the future and applied to the study of molecular ion chemistry.

DOI
10.1063/1.5031145

Related papers

Increased Control over Reaction Conditions in a Hybrid Trap

Pascal Eberle

This thesis presents work towards increased control over reaction conditions in a hybrid trap, which is composed of an ion trap spatially overlapped with a magneto-optical trap (MOT). \nA novel type of hybrid trap is presented with the aim to increase the control over collision energies. As normally on our setup both the neutral and ionic species are continuously cooled, collision energies are low and hard to control. To solve this problem, a dynamic MOT was created, where an atom cloud is shuttled between two off-center positions within the trap. A detailed description of the new hybrid trap setup is presented. The generation of the MOT laser light and its manipulation inside an acousto-optical modulator setup driven by a home-built radio-freequency setup is discussed. The shuttling atom cloud was analysed by time-of-flight experiments, which were compared to results from Monte Carlo trajectory simulations. During reaction measurements, the atoms can be moved at velocities of 3.1 to 4.8 m/s, corresponding to kinetic energies of the rubidium atoms of Ekin = 50 mK to 120 mK. \nFor the ions, work towards implementing vibrationally state-selected molecular oxygen ions is presented. Ions were produced by resonant multiphoton ionisation and spectroscopy was performed on the 3dδ ³Φ Rydberg states. First reactions of molecular oxygen ions in the vibrational ground state with a stationary atom cloud were measured. It was found that the reaction rate did not depend on the excited state fraction of the rubidium atoms. This was rationalised with the crossing of the potential energy surface of a charge-transfer exit channel close to the potential minimum of the ground-state entrance-channel potential energy surface.

•Jan 1, 2020•0 citations

A Dynamic Ion–Atom Hybrid Trap for High‐Resolution Cold‐Collision Studies

Pascal Eberle, Alexander Dörfler, Claudio von Planta +2 more

We present a dynamic ion-atom hybrid trap for studies of cold ion-neutral collisions and reactions with a significantly improved energy resolution compared with previous experiments. Our approach is based on pushing a cloud of laser-cooled Rb atoms through a stationary Coulomb crystal of cold ions by using precisely controlled, tunable radiation pressure forces. We demonstrate the tuning of the atom kinetic energies over an interval ranging from 30 mK up to 350 mK with energy spreads as low as 24 mK, inferred from the comparison of experimental time-of-flight measurements with Monte Carlo trajectory simulations. We also demonstrate the first applications of our method to the investigation of chemical reactions. Our development opens up perspectives for accurate studies of the energy dependence of the reaction rates, the dynamics, and the reaction-product ratios of the ion-neutral processes in the cold regime. It also paves the way for the realization of fully energy- and state-controlled cold-collision experiments.

ChemPhysChem•Aug 24, 2016•17 citations

Buffer gas cooling of ions in radio-frequency traps using ultracold atoms

Eleanor Trimby, Henrik Hirzler, Henning A. Fürst +3 more

Abstract Reaching ultracold temperatures within hybrid atom–ion systems is a major limiting factor for control and exploration of the atom–ion interaction in the quantum regime. In this work, we present results on numerical simulations of trapped ion buffer gas cooling using an ultracold atomic gas in a large number of experimentally realistic scenarios. We explore the suppression of micromotion-induced heating effects through optimization of trap parameters for various radio-frequency (rf) traps and rf driving schemes including linear and octupole traps, digital Paul traps, rotating traps and hybrid optical/rf traps. We find that very similar ion energies can be reached in all of them even when considering experimental imperfections that cause so-called excess micromotion. Moreover we look into a quantum description of the system and show that quantum mechanics cannot save the ion from micromotion-induced heating in an atom–ion collision. The results suggest that buffer gas cooling can be used to reach close to the ion’s groundstate of motion and is even competitive when compared to some sub-Doppler cooling techniques such as Sisyphus cooling. Thus, buffer gas cooling is a viable alternative for ions that are not amenable to laser cooling, a result that may be of interest for studies into cold controlled quantum chemistry and charged impurity physics.

arXiv:2109.15195•New Journal of Physics•Feb 22, 2022•15 citations

Experimental techniques for cold chemistry and molecular spectroscopy in an ion trap

Kevin Sheridan

A range of experimental techniques for application in reaction studies between ionic and neutral atoms/molecules and high resolution spectroscopy experiments with sympathetically cooled molecular ions are presented. A novel ion trap loading scheme using the photo-ionisation of atoms generated by the pulsed laser ablation of a solid calcium target has been characterised. We have identified the range of ablation laser fluences that must be used in order to produce a flux of neutral calcium atoms, which is a prerequisite for isotope selective ion trap loading. Calcium ions are trapped and laser cooled in a linear radio-frequency ion trap. We have developed a spectroscopy scheme that allows the entire fluorescence spectrum of trapped ions to be rapidly collected with high precision while maintaining a low ion temperature and good ion localisation throughout interrogation. The scheme has been demonstrated by measuring the saturation intensity of the calcium ion 4S1/2?4P1/2 transition. We have developed a novel scheme to measure the secular motion of trapped ions and demonstrated the application of the technique to ion-neutral collision reaction experiments. Employing pulsed excitation and Doppler velocimetry, we have measured the centre-of-mass mode frequency of single ions as well as large ion crystals with a frequency precision better than 2x10-3 within an interrogation time on the order of seconds. This method has been used to measure the mass of ions and observe charge exchange collisions between trapped calcium isotopes. In particular, we have measured the 44Ca++40Ca!40Ca++44Ca reaction cross section and demonstrated the single-event resolution of the technique. Finally, we have developed a novel all-optical broadband scheme for exciting, amplifying and measuring the secular motion of ions in the trap. Oscillation induced by optical excitation has been coherently amplified to control and measure the ion's secular motion. Requiring only a single interrogation laser, the ion's oscillation amplitude can be precisely controlled. The application of this technique to non-destructive spectroscopy of trapped molecular ions is discussed.

•Oct 3, 2013•0 citations

Control of Chemical Reactions in Radiofrequency Ion Traps

Prerna Paliwal, Jutta Toscano, Stefan Willitsch

Over the past few decades, radiofrequency ion traps have become an attractive platform for studying chemical reactions as they enable a high degree of control over ion-molecule dynamics. In this review, we summarize techniques for the trapping and cooling of atomic and molecular ions in radiofrequency traps, including Doppler and resolved-sideband laser cooling, sympathetic cooling, and cryogenic buffer-gas methods. We discuss strategies for controlling key reaction parameters: the preparation of specific internal quantum states by internal cooling, optical pumping, state-selective photoionization and quantum logic spectroscopy; the manipulation of collision energies through micromotion control, dynamic trapping, and combination with molecular beams; and the selection of molecular structure via isotopic substitution, conformational separation, and isomer-specific ion generation. We illustrate applications of these approaches by discussing studies on quantum-state-dependent kinetics, quantum resonance effects, and structure-sensitive reactivity in ion-neutral collisions. We conclude by outlining future challenges, including full state-to-state reaction mapping, reaching the ultracold quantum regime free of micromotion, and the exploration of complex and chiral systems.

arXiv:2510.09298•Annual Review of Physical Chemistry•Apr 20, 2026•0 citations

Ion-Atom and Ion-Molecule Hybrid Systems: Ion-Neutral Chemistry at Ultralow Energies

Pascal Eberle, Alexander Dörfler, Claudio von Planta +5 more

The study of chemical reactions between ions and neutral species at very low energies reveals precise informations about the dynamics of collisions and fine details of intermolecular interactions. Here, we report progress towards the development of next- generation experiments for the investigation of cold ion-neutral reactions. First, we present a new ''dynamic" hybrid ion-atom trap which enables the study of collisions with a superior energy resolution accessing a regime in which quantum scattering resonances may become observable. Second, we discuss and numerically characterize the concept and properties of a hybrid trap for cold neutral molecules and molecular ions which paves the way for the study of ion-molecule reactions in the millikelvin regime.

Journal of Physics Conference Series•Sep 7, 2015•15 citations
We demonstrate an ion shuttling technique for high-resolution control of atom-ion collision energy by translating an ion held within a radio-frequency trap through a magneto-optical atom trap. The technique is demonstrated both experimentally and through numerical simulations, with the experimental results indicating control of ion kinetic energies from 0.05 to 1 K with a fractional resolution of ∼10 and the simulations demonstrating that kinetic energy control up to 120 K with a maximum predicted resolution of ∼100 is possible, offering order-of-magnitude improvements over most alternative techniques. Finally, we perform a proof-of-principle chemistry experiment using this technique and outline how the method may be refined in the future and applied to the study of molecular ion chemistry.
This thesis presents work towards increased control over reaction conditions in a hybrid trap, which is composed of an ion trap spatially overlapped with a magneto-optical trap (MOT). \nA novel type of hybrid trap is presented with the aim to increase the control over collision energies. As normally on our setup both the neutral and ionic species are continuously cooled, collision energies are low and hard to control. To solve this problem, a dynamic MOT was created, where an atom cloud is shuttled between two off-center positions within the trap. A detailed description of the new hybrid trap setup is presented. The generation of the MOT laser light and its manipulation inside an acousto-optical modulator setup driven by a home-built radio-freequency setup is discussed. The shuttling atom cloud was analysed by time-of-flight experiments, which were compared to results from Monte Carlo trajectory simulations. During reaction measurements, the atoms can be moved at velocities of 3.1 to 4.8 m/s, corresponding to kinetic energies of the rubidium atoms of Ekin = 50 mK to 120 mK. \nFor the ions, work towards implementing vibrationally state-selected molecular oxygen ions is presented. Ions were produced by resonant multiphoton ionisation and spectroscopy was performed on the 3dδ ³Φ Rydberg states. First reactions of molecular oxygen ions in the vibrational ground state with a stationary atom cloud were measured. It was found that the reaction rate did not depend on the excited state fraction of the rubidium atoms. This was rationalised with the crossing of the potential energy surface of a charge-transfer exit channel close to the potential minimum of the ground-state entrance-channel potential energy surface.
We present a dynamic ion-atom hybrid trap for studies of cold ion-neutral collisions and reactions with a significantly improved energy resolution compared with previous experiments. Our approach is based on pushing a cloud of laser-cooled Rb atoms through a stationary Coulomb crystal of cold ions by using precisely controlled, tunable radiation pressure forces. We demonstrate the tuning of the atom kinetic energies over an interval ranging from 30 mK up to 350 mK with energy spreads as low as 24 mK, inferred from the comparison of experimental time-of-flight measurements with Monte Carlo trajectory simulations. We also demonstrate the first applications of our method to the investigation of chemical reactions. Our development opens up perspectives for accurate studies of the energy dependence of the reaction rates, the dynamics, and the reaction-product ratios of the ion-neutral processes in the cold regime. It also paves the way for the realization of fully energy- and state-controlled cold-collision experiments.
Abstract Reaching ultracold temperatures within hybrid atom–ion systems is a major limiting factor for control and exploration of the atom–ion interaction in the quantum regime. In this work, we present results on numerical simulations of trapped ion buffer gas cooling using an ultracold atomic gas in a large number of experimentally realistic scenarios. We explore the suppression of micromotion-induced heating effects through optimization of trap parameters for various radio-frequency (rf) traps and rf driving schemes including linear and octupole traps, digital Paul traps, rotating traps and hybrid optical/rf traps. We find that very similar ion energies can be reached in all of them even when considering experimental imperfections that cause so-called excess micromotion. Moreover we look into a quantum description of the system and show that quantum mechanics cannot save the ion from micromotion-induced heating in an atom–ion collision. The results suggest that buffer gas cooling can be used to reach close to the ion’s groundstate of motion and is even competitive when compared to some sub-Doppler cooling techniques such as Sisyphus cooling. Thus, buffer gas cooling is a viable alternative for ions that are not amenable to laser cooling, a result that may be of interest for studies into cold controlled quantum chemistry and charged impurity physics.
A range of experimental techniques for application in reaction studies between ionic and neutral atoms/molecules and high resolution spectroscopy experiments with sympathetically cooled molecular ions are presented. A novel ion trap loading scheme using the photo-ionisation of atoms generated by the pulsed laser ablation of a solid calcium target has been characterised. We have identified the range of ablation laser fluences that must be used in order to produce a flux of neutral calcium atoms, which is a prerequisite for isotope selective ion trap loading. Calcium ions are trapped and laser cooled in a linear radio-frequency ion trap. We have developed a spectroscopy scheme that allows the entire fluorescence spectrum of trapped ions to be rapidly collected with high precision while maintaining a low ion temperature and good ion localisation throughout interrogation. The scheme has been demonstrated by measuring the saturation intensity of the calcium ion 4S1/2?4P1/2 transition. We have developed a novel scheme to measure the secular motion of trapped ions and demonstrated the application of the technique to ion-neutral collision reaction experiments. Employing pulsed excitation and Doppler velocimetry, we have measured the centre-of-mass mode frequency of single ions as well as large ion crystals with a frequency precision better than 2x10-3 within an interrogation time on the order of seconds. This method has been used to measure the mass of ions and observe charge exchange collisions between trapped calcium isotopes. In particular, we have measured the 44Ca++40Ca!40Ca++44Ca reaction cross section and demonstrated the single-event resolution of the technique. Finally, we have developed a novel all-optical broadband scheme for exciting, amplifying and measuring the secular motion of ions in the trap. Oscillation induced by optical excitation has been coherently amplified to control and measure the ion's secular motion. Requiring only a single interrogation laser, the ion's oscillation amplitude can be precisely controlled. The application of this technique to non-destructive spectroscopy of trapped molecular ions is discussed.
Over the past few decades, radiofrequency ion traps have become an attractive platform for studying chemical reactions as they enable a high degree of control over ion-molecule dynamics. In this review, we summarize techniques for the trapping and cooling of atomic and molecular ions in radiofrequency traps, including Doppler and resolved-sideband laser cooling, sympathetic cooling, and cryogenic buffer-gas methods. We discuss strategies for controlling key reaction parameters: the preparation of specific internal quantum states by internal cooling, optical pumping, state-selective photoionization and quantum logic spectroscopy; the manipulation of collision energies through micromotion control, dynamic trapping, and combination with molecular beams; and the selection of molecular structure via isotopic substitution, conformational separation, and isomer-specific ion generation. We illustrate applications of these approaches by discussing studies on quantum-state-dependent kinetics, quantum resonance effects, and structure-sensitive reactivity in ion-neutral collisions. We conclude by outlining future challenges, including full state-to-state reaction mapping, reaching the ultracold quantum regime free of micromotion, and the exploration of complex and chiral systems.
The study of chemical reactions between ions and neutral species at very low energies reveals precise informations about the dynamics of collisions and fine details of intermolecular interactions. Here, we report progress towards the development of next- generation experiments for the investigation of cold ion-neutral reactions. First, we present a new ''dynamic" hybrid ion-atom trap which enables the study of collisions with a superior energy resolution accessing a regime in which quantum scattering resonances may become observable. Second, we discuss and numerically characterize the concept and properties of a hybrid trap for cold neutral molecules and molecular ions which paves the way for the study of ion-molecule reactions in the millikelvin regime.