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

APS

Observation of Cold Collisions between Trapped Ions and Trapped Atoms

Fedja Oručević, Marko Cetina, Vladan Vuletić, Andrew T. Grier

Published Jun 1, 2009• 0 citations
OpenAlex

Abstract

We study cold collisions between trapped ions and trapped atoms in the semiclassical (Langevin) regime. Using Yb(+) ions confined in a Paul trap and Yb atoms in a magneto-optical trap, we investigate charge-exchange collisions of several isotopes over three decades of collision energies down to 3 μeV (k[subscript B]×35 mK). The minimum measured rate coefficient of 6×10(-10) cm(3) s(-1) is in good agreement with that derived from a Langevin model for an atomic polarizability of 143 a.u.

Related papers

Observation of Cold Collisions between Trapped Ions and Trapped Atoms

Andrew T. Grier, Marko Cetina, Fedja Oručević +1 more

We study cold collisions between trapped ions and trapped atoms in the semiclassical (Langevin) regime. Using ${\mathrm{Yb}}^{+}$ ions confined in a Paul trap and Yb atoms in a magneto-optical trap, we investigate charge-exchange collisions of several isotopes over three decades of collision energies down to $3\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$ (${k}_{B}\ifmmode\times\else\texttimes\fi{}35\text{ }\text{ }\mathrm{mK}$). The minimum measured rate coefficient of $6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\text{ }\text{ }{\mathrm{cm}}^{3}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$ is in good agreement with that derived from a Langevin model for an atomic polarizability of 143 a.u.

arXiv:0808.3620•Physical Review Letters•Jun 4, 2009•262 citations

Measurement of collisions between laser-cooled cesium atoms and trapped cesium ions

Sourav Dutta, S. A. Rangwala

We report the measurement of collision rate coefficient for collisions between ultracold Cs atoms and low-energy $\mathrm{C}{\mathrm{s}}^{+}$ ions. The experiments are performed in a hybrid trap consisting of a magneto-optical trap (MOT) for Cs atoms and a Paul trap for $\mathrm{C}{\mathrm{s}}^{+}$ ions. The ion-atom collisions impart kinetic energy to the ultracold Cs atoms, resulting in their escape from the shallow MOT and, therefore, in a reduction in the number of Cs atoms in the MOT. By monitoring, using fluorescence measurements, the Cs atom number, and the MOT loading dynamics and then fitting the data to a rate equation model, the ion-atom collision rate is derived. The $\mathrm{Cs}\ensuremath{-}\mathrm{C}{\mathrm{s}}^{+}$ collision rate coefficient $9.3(\ifmmode\pm\else\textpm\fi{}0.4)(\ifmmode\pm\else\textpm\fi{}1.2)(\ifmmode\pm\else\textpm\fi{}3.5)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}\phantom{\rule{0.16em}{0ex}}{\mathrm{m}}^{3}\phantom{\rule{0.28em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}$, measured for an ion distribution with most probable collision energy of 95 meV $(\ensuremath{\approx}{\mathrm{k}}_{\mathrm{B}}\phantom{\rule{4pt}{0ex}}1100\phantom{\rule{4pt}{0ex}}\mathrm{K})$, is in fair agreement with theoretical calculations. As an intermediate step, we also determine the photoionization cross section of Cs $6{P}_{3/2}$ atoms at 473 nm wavelength to be $2.28(\ifmmode\pm\else\textpm\fi{}0.33)\phantom{\rule{4pt}{0ex}}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}21}\phantom{\rule{0.16em}{0ex}}{\mathrm{m}}^{2}$.

arXiv:2008.08396•Physical Review A•Sep 8, 2020•4 citations

Ultracold, radiative charge transfer in hybrid Yb ion–Rb atom traps

B. M. McLaughlin, H D L Lamb, I C Lane +1 more

Ultracold hybrid ion–atom traps offer the possibility of microscopic manipulation of quantum coherences in the gas using the ion as a probe. However, inelastic processes, particularly charge transfer can be a significant process of ion loss and has been measured experimentally for the ion immersed in a Rb vapour. We use first-principles quantum chemistry codes to obtain the potential energy curves and dipole moments for the lowest-lying energy states of this complex. Calculations for the radiative decay processes cross sections and rate coefficients are presented for the total decay processes; and . Comparing the semi-classical Langevin approximation with the quantum approach, we find it provides a very good estimate of the background at higher energies. The results demonstrate that radiative decay mechanisms are important over the energy and temperature region considered. In fact, the Langevin process of ion–atom collisions dominates cold ion–atom collisions. For spin-dependent processes [ 1 ] the anisotropic magnetic dipole–dipole interaction and the second-order spin–orbit coupling can play important roles, inducing coupling between the spin and the orbital motion. They measured the spin-relaxing collision rate to be approximately five orders of magnitude higher than the charge-exchange collision rate [ 1 ]. Regarding the measured radiative charge transfer collision rate, we find that our calculation is in very good agreement with experiment and with previous calculations. Nonetheless, we find no broad resonances features that might underly a strong isotope effect. In conclusion, we find, in agreement with previous theory that the isotope anomaly observed in experiment remains an open question.

arXiv:1404.6579•Journal of Physics B Atomic Molecular and Optical Physics•Jul 4, 2014•20 citations

Three-body reaction dynamics in cold atom-ion experiments

Artjom Krükow

Over the recent years a new research field emerged that combines technologies for cooling and trapping of neutral atoms and charged ions in one experimental apparatus. These atom-ion hybrid traps enable the investigation of atom-ion interactions at unprecedentedly low collision energies targeting the ultracold s-wave regime. In this thesis I report on experiments performed in an hybrid atom-ion apparatus combining single Ba^+ or Rb^+ ions with ultracold neutral Rb atoms. The main focus of this work is studying the emerging three-body reaction dynamics in a cold charged gas. First, I will present measurements investigating cold reactions in the hetero-nuclear Ba^+ - Rb system. So far, most theoretical and experimental studies have been dealing with reactions between two particles. However, we find that three-body reactions already dominate over two-body ones at atomic densities down to 10^{−11} cm^{−3} once collision energies are in the low mK regime. We then investigate the energy scaling of inelastic ternary collisions between an ion and two atoms. A power-law scaling of the three-body rate coefficient is predicted by theory. We find agreement with the experiment if we include the ion’s kinetic energy distribution that we access numerically. The next study elaborates on the very first observation of ternary reactions in a hybrid cold atom-ion setup. For this we immerse a single Rb^+ ion into ultracold Rb atoms with sufficiently reduced excess micromotion. Occurring reactions are signaled by the creation of highly energetic Rb^+ ions. I will also showcase novel techniques to investigate the atom and the ion system by using the respective other one which were developed by us over the course of the last years. In order to reduce the total ion kinetic energy in a Paul trap one has to compensate the ion’s excess micromotion. This is routinely being done by analyzing the ion’s fluorescence. By observing collision energy dependent elastic atom-ion collisions in an ultracold atom cloud we directly infer the ion’s micromotion energy. This way we can perform atom-ion experiments with optically dark Rb^+ ions and good excess micromotion. Without the need of visible laser light for micromotion compensation we are able to investigate the evolution of quasi-static stray electric fields in a Paul trap over a period of several months. The last study I will present is targeted at neutral Rb only. There, we spectroscopically access the molecular state distribution of Rb_2 molecules formed in neutral three-body recombination by state-selective ionization of these molecules. Trapping and subsequent detection of these ions is being done with our Paul trap, which has the role of a very sensitive single ion detector in these measurements.

•Jan 1, 2016•0 citations

Charge transfer in cold Yb + +Rb collisions

Elvira R. Sayfutyarova, Alexei A. Buchachenko, Svetlana A. Yakovleva +1 more

Charge-transfer cold Yb${}^{+}$$+$ Rb collision dynamics is investigated theoretically using high-level ab initio potential energy curves, dipole moment functions, and nonadiabatic coupling matrix elements. Within the scalar-relativistic approximation, the radiative transitions from the entrance $A{\phantom{\rule{0.16em}{0ex}}}^{1}{\ensuremath{\Sigma}}^{+}$ to the ground $X{\phantom{\rule{0.16em}{0ex}}}^{1}{\ensuremath{\Sigma}}^{+}$ state are found to be the only efficient charge-transfer pathway. The spin-orbit coupling does not open other efficient pathways, but alters the potential energy curves and the transition dipole moment for the $A\ensuremath{-}X$ pair of states. The radiative, as well as the nonradiative, charge-transfer cross sections calculated within the ${10}^{\ensuremath{-}3}--10$ cm${}^{\ensuremath{-}1}$ collision energy range exhibit all features of the Langevin ion-atom collision regime, including a rich structure associated with centrifugal barrier tunneling (orbiting) resonances. Theoretical rate coefficients for two Yb isotopes agree well with those measured by immersing Yb${}^{+}$ ions in an ultracold Rb ensemble in a hybrid trap. Possible origins of discrepancy in the product distributions and relations to previously studied similar processes are discussed.

arXiv:1303.3093•Physical Review A•May 29, 2013•35 citations

Thermal atom-ion collisions in a K- Yb+ hybrid system

Thai M. Hoang, Peter D. D. Schwindt, Yuan‐Yu Jau

We present experimental studies of atom-ion collisions using buffer-gas cooled, trapped ytterbium (${\mathrm{Yb}}^{+}$) ions immersed in potassium (K) vapor. The range of the collisional temperature is on the order of several hundred kelvin (thermal regime). We have determined various collisional rate coefficients of the ${\mathrm{Yb}}^{+}$ ion per K-atom number density. We find the upper bounds of charge-exchange rate coefficients ${\ensuremath{\kappa}}_{\mathrm{ce}}$ to be $(12.7\ifmmode\pm\else\textpm\fi{}1.6)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{3}{\mathrm{s}}^{\ensuremath{-}1}$ for K-$^{171}\mathrm{Yb}^{+}$ and $(5.3\ifmmode\pm\else\textpm\fi{}0.7)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{3}{\mathrm{s}}^{\ensuremath{-}1}$ for K-$^{172}\mathrm{Yb}^{+}$. For both isotopes, the spin-destruction rate coefficient ${\ensuremath{\kappa}}_{\mathrm{sd}}$ has an upper bound at $(1.46\ifmmode\pm\else\textpm\fi{}0.77)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{3}{\mathrm{s}}^{\ensuremath{-}1}$. The spin-exchange rate coefficient ${\ensuremath{\kappa}}_{\mathrm{se}}$ is measured to be $(1.64\ifmmode\pm\else\textpm\fi{}0.51)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{3}{\mathrm{s}}^{\ensuremath{-}1}$. The relatively low charge-exchange rate reported here demonstrates the advantage of using K atoms to sympathetically cool ${\mathrm{Yb}}^{+}$ ions and the relatively high spin-exchange rate may benefit research work in quantum metrology and quantum information processing on an atom-ion platform using K atoms and ${\mathrm{Yb}}^{+}$ ions.

arXiv:1901.00905•Physical Review A•Aug 1, 2019•2 citations
We study cold collisions between trapped ions and trapped atoms in the semiclassical (Langevin) regime. Using Yb(+) ions confined in a Paul trap and Yb atoms in a magneto-optical trap, we investigate charge-exchange collisions of several isotopes over three decades of collision energies down to 3 μeV (k[subscript B]×35 mK). The minimum measured rate coefficient of 6×10(-10) cm(3) s(-1) is in good agreement with that derived from a Langevin model for an atomic polarizability of 143 a.u.
We study cold collisions between trapped ions and trapped atoms in the semiclassical (Langevin) regime. Using Yb+{\mathrm{Yb}}^{+}Yb+ ions confined in a Paul trap and Yb atoms in a magneto-optical trap, we investigate charge-exchange collisions of several isotopes over three decades of collision energies down to $3\text{ }\text{ }\ensuremath{\mu}\mathrm{eV}$ (${k}_{B}\ifmmode\times\else\texttimes\fi{}35\text{ }\text{ }\mathrm{mK}$). The minimum measured rate coefficient of $6\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}10}\text{ }\text{ }{\mathrm{cm}}^{3}\text{ }{\mathrm{s}}^{\ensuremath{-}1}$ is in good agreement with that derived from a Langevin model for an atomic polarizability of 143 a.u.
We report the measurement of collision rate coefficient for collisions between ultracold Cs atoms and low-energy Cs+\mathrm{C}{\mathrm{s}}^{+}Cs+ ions. The experiments are performed in a hybrid trap consisting of a magneto-optical trap (MOT) for Cs atoms and a Paul trap for Cs+\mathrm{C}{\mathrm{s}}^{+}Cs+ ions. The ion-atom collisions impart kinetic energy to the ultracold Cs atoms, resulting in their escape from the shallow MOT and, therefore, in a reduction in the number of Cs atoms in the MOT. By monitoring, using fluorescence measurements, the Cs atom number, and the MOT loading dynamics and then fitting the data to a rate equation model, the ion-atom collision rate is derived. The $\mathrm{Cs}\ensuremath{-}\mathrm{C}{\mathrm{s}}^{+}$ collision rate coefficient $9.3(\ifmmode\pm\else\textpm\fi{}0.4)(\ifmmode\pm\else\textpm\fi{}1.2)(\ifmmode\pm\else\textpm\fi{}3.5)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}\phantom{\rule{0.16em}{0ex}}{\mathrm{m}}^{3}\phantom{\rule{0.28em}{0ex}}{\mathrm{s}}^{\ensuremath{-}1}$, measured for an ion distribution with most probable collision energy of 95 meV $(\ensuremath{\approx}{\mathrm{k}}_{\mathrm{B}}\phantom{\rule{4pt}{0ex}}1100\phantom{\rule{4pt}{0ex}}\mathrm{K})$, is in fair agreement with theoretical calculations. As an intermediate step, we also determine the photoionization cross section of Cs 6P3/26{P}_{3/2}6P3/2​ atoms at 473 nm wavelength to be $2.28(\ifmmode\pm\else\textpm\fi{}0.33)\phantom{\rule{4pt}{0ex}}\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}21}\phantom{\rule{0.16em}{0ex}}{\mathrm{m}}^{2}$.
Ultracold hybrid ion–atom traps offer the possibility of microscopic manipulation of quantum coherences in the gas using the ion as a probe. However, inelastic processes, particularly charge transfer can be a significant process of ion loss and has been measured experimentally for the ion immersed in a Rb vapour. We use first-principles quantum chemistry codes to obtain the potential energy curves and dipole moments for the lowest-lying energy states of this complex. Calculations for the radiative decay processes cross sections and rate coefficients are presented for the total decay processes; and . Comparing the semi-classical Langevin approximation with the quantum approach, we find it provides a very good estimate of the background at higher energies. The results demonstrate that radiative decay mechanisms are important over the energy and temperature region considered. In fact, the Langevin process of ion–atom collisions dominates cold ion–atom collisions. For spin-dependent processes [ 1 ] the anisotropic magnetic dipole–dipole interaction and the second-order spin–orbit coupling can play important roles, inducing coupling between the spin and the orbital motion. They measured the spin-relaxing collision rate to be approximately five orders of magnitude higher than the charge-exchange collision rate [ 1 ]. Regarding the measured radiative charge transfer collision rate, we find that our calculation is in very good agreement with experiment and with previous calculations. Nonetheless, we find no broad resonances features that might underly a strong isotope effect. In conclusion, we find, in agreement with previous theory that the isotope anomaly observed in experiment remains an open question.
Over the recent years a new research field emerged that combines technologies for cooling and trapping of neutral atoms and charged ions in one experimental apparatus. These atom-ion hybrid traps enable the investigation of atom-ion interactions at unprecedentedly low collision energies targeting the ultracold s-wave regime. In this thesis I report on experiments performed in an hybrid atom-ion apparatus combining single Ba^+ or Rb^+ ions with ultracold neutral Rb atoms. The main focus of this work is studying the emerging three-body reaction dynamics in a cold charged gas. First, I will present measurements investigating cold reactions in the hetero-nuclear Ba^+ - Rb system. So far, most theoretical and experimental studies have been dealing with reactions between two particles. However, we find that three-body reactions already dominate over two-body ones at atomic densities down to 10^{−11} cm^{−3} once collision energies are in the low mK regime. We then investigate the energy scaling of inelastic ternary collisions between an ion and two atoms. A power-law scaling of the three-body rate coefficient is predicted by theory. We find agreement with the experiment if we include the ion’s kinetic energy distribution that we access numerically. The next study elaborates on the very first observation of ternary reactions in a hybrid cold atom-ion setup. For this we immerse a single Rb^+ ion into ultracold Rb atoms with sufficiently reduced excess micromotion. Occurring reactions are signaled by the creation of highly energetic Rb^+ ions. I will also showcase novel techniques to investigate the atom and the ion system by using the respective other one which were developed by us over the course of the last years. In order to reduce the total ion kinetic energy in a Paul trap one has to compensate the ion’s excess micromotion. This is routinely being done by analyzing the ion’s fluorescence. By observing collision energy dependent elastic atom-ion collisions in an ultracold atom cloud we directly infer the ion’s micromotion energy. This way we can perform atom-ion experiments with optically dark Rb^+ ions and good excess micromotion. Without the need of visible laser light for micromotion compensation we are able to investigate the evolution of quasi-static stray electric fields in a Paul trap over a period of several months. The last study I will present is targeted at neutral Rb only. There, we spectroscopically access the molecular state distribution of Rb_2 molecules formed in neutral three-body recombination by state-selective ionization of these molecules. Trapping and subsequent detection of these ions is being done with our Paul trap, which has the role of a very sensitive single ion detector in these measurements.
Charge-transfer cold Yb+{}^{+}++++ Rb collision dynamics is investigated theoretically using high-level ab initio potential energy curves, dipole moment functions, and nonadiabatic coupling matrix elements. Within the scalar-relativistic approximation, the radiative transitions from the entrance $A{\phantom{\rule{0.16em}{0ex}}}^{1}{\ensuremath{\Sigma}}^{+}$ to the ground $X{\phantom{\rule{0.16em}{0ex}}}^{1}{\ensuremath{\Sigma}}^{+}$ state are found to be the only efficient charge-transfer pathway. The spin-orbit coupling does not open other efficient pathways, but alters the potential energy curves and the transition dipole moment for the $A\ensuremath{-}X$ pair of states. The radiative, as well as the nonradiative, charge-transfer cross sections calculated within the ${10}^{\ensuremath{-}3}--10$ cm${}^{\ensuremath{-}1}$ collision energy range exhibit all features of the Langevin ion-atom collision regime, including a rich structure associated with centrifugal barrier tunneling (orbiting) resonances. Theoretical rate coefficients for two Yb isotopes agree well with those measured by immersing Yb+{}^{+}+ ions in an ultracold Rb ensemble in a hybrid trap. Possible origins of discrepancy in the product distributions and relations to previously studied similar processes are discussed.
We present experimental studies of atom-ion collisions using buffer-gas cooled, trapped ytterbium (Yb+{\mathrm{Yb}}^{+}Yb+) ions immersed in potassium (K) vapor. The range of the collisional temperature is on the order of several hundred kelvin (thermal regime). We have determined various collisional rate coefficients of the Yb+{\mathrm{Yb}}^{+}Yb+ ion per K-atom number density. We find the upper bounds of charge-exchange rate coefficients ${\ensuremath{\kappa}}_{\mathrm{ce}}$ to be $(12.7\ifmmode\pm\else\textpm\fi{}1.6)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{3}{\mathrm{s}}^{\ensuremath{-}1}$ for K-171Yb+^{171}\mathrm{Yb}^{+}171Yb+ and $(5.3\ifmmode\pm\else\textpm\fi{}0.7)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}14}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{3}{\mathrm{s}}^{\ensuremath{-}1}$ for K-172Yb+^{172}\mathrm{Yb}^{+}172Yb+. For both isotopes, the spin-destruction rate coefficient ${\ensuremath{\kappa}}_{\mathrm{sd}}$ has an upper bound at $(1.46\ifmmode\pm\else\textpm\fi{}0.77)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{3}{\mathrm{s}}^{\ensuremath{-}1}$. The spin-exchange rate coefficient ${\ensuremath{\kappa}}_{\mathrm{se}}$ is measured to be $(1.64\ifmmode\pm\else\textpm\fi{}0.51)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}9}\phantom{\rule{4pt}{0ex}}{\mathrm{cm}}^{3}{\mathrm{s}}^{\ensuremath{-}1}$. The relatively low charge-exchange rate reported here demonstrates the advantage of using K atoms to sympathetically cool Yb+{\mathrm{Yb}}^{+}Yb+ ions and the relatively high spin-exchange rate may benefit research work in quantum metrology and quantum information processing on an atom-ion platform using K atoms and Yb+{\mathrm{Yb}}^{+}Yb+ ions.