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:1709.02399 · Science

Synthesis of mixed hypermetallic oxide BaOCa + from laser-cooled reagents in an atom-ion hybrid trap

Prateek Puri, Michael Mills, Christian Schneider, I. Simbotin, John A. Jr. Montgomery, Robin Côté, Arthur G. Suits, Eric R. Hudson

Published Sep 8, 2017• 70 citations
arXivHTMLPDF

Abstract

A chilly meeting of barium and calcium The periodic table is an excellent predictor of element ratios in chemical compounds that form at temperatures that we commonly experience, give or take a factor of 10. Strange things start happening at hot and cold extremes, though. Puri et al. take advantage of extreme cold to observe the formation of the BaOCa + ion, an electron-deficient alternative to conventional binary barium or calcium oxides. They first prepared cold barium methoxide ions and then exposed them to calcium atoms cooled to thousandths of a kelvin. Mass spectral and theoretical analyses revealed a barrierless reaction pathway in which triplet-state calcium displaces the methyl group. Science , this issue p. 1370

DOI
10.1126/science.aan4701

Related papers

Negative Calcium Ions Are Stable—In Spite of the Conventional Wisdom

Bertram M. Schwarzschild

Most atomic species—roughly 80% of the periodic table—can form stable negative ions in their gaseous phase. The most notable and easily understood exceptions are the noble gas atoms, the symmetry of whose completely filled electron shells offers no handhold for a would-be extra tenant. The alkaline earths—calcium, strontium, barium and their group IIA cousins—are similarly inhospitable, or so the standard textbooks assure us. Two back-to-back reports in a recent issue of Physical Review Letters have now disabused us of this venerable assurance.

Physics Today•Jun 1, 1988•4 citations

Production of translationally cold barium monohalide ions

Michael V. DePalatis, Michael Chapman

We have produced sympathetically cooled barium monohalide ions Ba${X}^{+}$ ($X=\text{F}$, Cl, Br) by reacting trapped, laser-cooled Ba${}^{+}$ ions with room-temperature gas-phase neutral halogen-containing molecules. Reaction rates for two of these (SF${}_{6}$ and CH${}_{3}$Cl) have been measured and were found to be in agreement with classical models. Ba${X}^{+}$ ions are promising candidates for cooling to the rovibrational ground state, and our method presents a straightforward way to produce these polar molecular ions.

arXiv:1306.0035•Physical Review A•Aug 5, 2013•8 citations

Controlled quantum-state-resolved chemistry to enable quantum logic with molecular ions

Michael Charles Mills

This dissertation describes experiments performed in the MOTion trap, a hybrid atom--ion trap comprised of a magneto-optical trap (MOT) and a linear Paul trap with an integrated time-of-flight mass spectrometer (ToF-MS).We aim to sympathetically cool the vibrational and rotational degrees of freedom of a BaCl$^+$ molecular ion by overlapping a cold ($\\sim4$~mK) Ca MOT.\nThis sympathetic cooling can prepare a molecular ion in its rovibrational quantum ground state, providing a method for state preparation for applications in molecular ion quantum logic.\nWhile collisions between the molecular ion and the cold atoms can cool the internal degrees of freedom, chemical reactions are also possible for electronically excited atoms.\nAs such, we study these excited-state atom--ion reactions at low temperature $<1$~K and develop tools to control these collisions.\nWe make the first experimental observation of reaction blockading, an effect that suppresses excited-state reactions at low temperature, and develop a method to reverse this suppression if desired with the addition of a catalyst laser, providing a means to optically control such reactions.Beyond its intended purpose of studying and achieving sympathetic cooling, we find that this apparatus is a powerful tool for chemical studies.By imaging the ions, we can observe reactions occurring one atom at a time.\nWe can precisely tune the collision energy or temperature down to the mK regime to as high as $\\sim$10~K using techniques described in this dissertation, allowing controlled interrogation of these low-temperature reactions.\nFurther, using lasers to address electronic transitions, we can precisely control the quantum state of the reactants, and we can measure the reaction products with the ToF-MS.\nA testament to the value of this apparatus is the study of BaOCa$^+$ described in this dissertation.\nUsing the tools of the MOTion trap, we were able to identify the production of BaOCa$^+$, the first observation of a mixed hypermetallic oxide, and determine the path of reaction as BaOCH$_3^+$ + Ca($4s4p$~$^3P_J$) $\\rightarrow$ BaOCa$^+$ + CH$_3$.In addition to developing control of these atom--ion interactions towards sympathetic cooling of molecular ions, we also work towards further developing new quantum logic schemes for molecular ions, such as dipolar quantum logic, dipole--phonon quantum logic (DPQL), and electric-field gradient gates (EGGs).Specifically, we propose a class of molecules particularly well-suited for DPQL, the alkaline earth monoxide cations, that can also be added to existing atomic ion experiments with minimal additional experimental complexity.\nWe further develop the techniques for DPQL and propose methods for single- and two-qubit gates, outlining a path towards universal quantum computation with molecular ions.

•Jan 1, 2020•0 citations

Chemical reactions between cold trapped Ba+ ions and neutral molecules in the gas phase

Bernhard Roth, David Offenberg, C. B. Zhang +1 more

Using a laser-cooled ion trapping apparatus, we have investigated laser-induced chemical reactions between cold trapped ${\mathrm{Ba}}^{+}$ ions and several neutral molecular gases at room temperature, ${\mathrm{O}}_{2}$, $\mathrm{C}{\mathrm{O}}_{2}$, and ${\mathrm{N}}_{2}\mathrm{O}$, leading to the production of cold trapped $(\ensuremath{\approx}20\phantom{\rule{0.3em}{0ex}}\mathrm{mK})$ $\mathrm{Ba}{\mathrm{O}}^{+}$ ions. The $\mathrm{Ba}{\mathrm{O}}^{+}$ ions were converted back to ${\mathrm{Ba}}^{+}$ ions via reaction with room-temperature CO. Reaction rates were determined by employing molecular dynamics simulations. The cold mixed-species ion ensembles produced were used for studying the efficiency of sympathetic cooling, by variation of the ratio of laser-cooled to sympathetically cooled ion numbers. In one extreme case, 20 laser-cooled $^{138}\mathrm{Ba}^{+}$ ions were capable of maintaining the translational temperature of 120 sympathetically cooled barium isotopes $(^{135--137}\mathrm{Ba}^{+})$ and 430 $^{138}\mathrm{Ba}^{16}{\mathrm{O}}^{+}$ molecules at approximately $25\phantom{\rule{0.3em}{0ex}}\mathrm{mK}$.

Physical Review A•Oct 24, 2008•28 citations

Ion-neutral chemistry at ultralow energies:Dynamics of reactive collisions between laser-cooled Ca + or Ba + ions and Rb atoms in an ion-atom hybrid trap

Olivier Dulieu, Felix H. J. Hall, Pascal Eberle +4 more

APS•May 1, 2013•0 citations

Creation of cold and dense ensembles of calcium atoms

Felix Vogt

Das Verhalten von kalten (15 µK) Calcium-Atomen in einer geeigneten optischen Dipolfalle wurde untersucht.Prozesse, die die Phasenraumdichte des in der Dipolfalle gespeicherten Calcium-Ensembles begrenzen, wurden identifiziert und untersucht.Zusammen mit der experimentell bestimmten Grundzustands-Streulänge wurden die Aussichten für die Realisierung eines Calcium Bose-Einstein-Kondensats erörtert.Die Dipolfalle wurde so konzipiert, dass ihr Betrieb mit der Laserkühlung auf dem schmalen Interkombinationsübergang 4s 2 1 S 0 → 4s4p 3 P 1 bei 657 nm verträglich ist.Atome, die in einer auf dem Interkombinationsübergang operierenden magneto-optischen Falle gekühlt und gespeichert werden, können nur begrenzt in die Dipolfalle transferiert werden, da das 657 nm Laserlicht zur Photoassoziation von Ca 2 -Molekülen führt, die aus der Dipolfalle verloren gehen.Die entsprechende Zweikörper-Verlustrate konnte zusammen mit der Einfangrate der Dipolfalle und den Verlustraten der magneto-optischen Falle in einem Modell erfaßt werden, das die Ladedynamik der Dipolfalle beschreibt.Eine maximale Steigerung der Phasenraumdichte des Calcium-Ensembles auf 0.045 konnte im Kreuzungsbereich zweier Dipolfallen erreicht werden.Der Transfer von Atomen aus einer Einzelfalle in den Kreuzungsbereich beider Fallen wird durch elastische Stöße hervorgerufen.Die Teilchenzahl im Kreuzungsbereich wird durch inelastische Dreikörper-Stöße begrenzt, deren Rate jedoch mehr als eine Größenordnung kleiner ist als die elastische Stoßrate.Die Ladedynamik des Kreuzungsbereichs wird durch ein Modell beschrieben, das die verschiedenen Raten berücksichtigt.Die Grundzustands-Streulänge wurde durch Photoassoziations-Spektroskopie unterhalb der 4s 2 1 S 0 + 4s4p 1 P 1 Asymptote bestimmt.Im Vergleich zu früheren Messungen erlaubten verbesserte experimentelle Bedingungen einen größeren Bereich von Kernabständen zu erfassen.Die damit verbundenen genaueren Messungen liefern nun einen Bereich der Streulänge zwischen 340a 0 und 700a 0 und lösen damit die Diskrepanz zwischen den Ergebnissen früherer Messungen.Als Ergebnis der Untersuchungen ist es nun möglich den experimentell aussichtsreichsten Weg für die Erzeugung eines Calcium Bose-Einstein-Kondensats aufzuzeigen, das zahlreiche neue und faszinierende Forschungsmöglichkeiten bietet.

•Jan 1, 2009•0 citations
A chilly meeting of barium and calcium The periodic table is an excellent predictor of element ratios in chemical compounds that form at temperatures that we commonly experience, give or take a factor of 10. Strange things start happening at hot and cold extremes, though. Puri et al. take advantage of extreme cold to observe the formation of the BaOCa + ion, an electron-deficient alternative to conventional binary barium or calcium oxides. They first prepared cold barium methoxide ions and then exposed them to calcium atoms cooled to thousandths of a kelvin. Mass spectral and theoretical analyses revealed a barrierless reaction pathway in which triplet-state calcium displaces the methyl group. Science , this issue p. 1370
Most atomic species—roughly 80% of the periodic table—can form stable negative ions in their gaseous phase. The most notable and easily understood exceptions are the noble gas atoms, the symmetry of whose completely filled electron shells offers no handhold for a would-be extra tenant. The alkaline earths—calcium, strontium, barium and their group IIA cousins—are similarly inhospitable, or so the standard textbooks assure us. Two back-to-back reports in a recent issue of Physical Review Letters have now disabused us of this venerable assurance.
We have produced sympathetically cooled barium monohalide ions BaX+{X}^{+}X+ (X=FX=\text{F}X=F, Cl, Br) by reacting trapped, laser-cooled Ba+{}^{+}+ ions with room-temperature gas-phase neutral halogen-containing molecules. Reaction rates for two of these (SF6{}_{6}6​ and CH3{}_{3}3​Cl) have been measured and were found to be in agreement with classical models. BaX+{X}^{+}X+ ions are promising candidates for cooling to the rovibrational ground state, and our method presents a straightforward way to produce these polar molecular ions.
This dissertation describes experiments performed in the MOTion trap, a hybrid atom--ion trap comprised of a magneto-optical trap (MOT) and a linear Paul trap with an integrated time-of-flight mass spectrometer (ToF-MS).We aim to sympathetically cool the vibrational and rotational degrees of freedom of a BaCl+^++ molecular ion by overlapping a cold (sim4\\sim4sim4~mK) Ca MOT.\nThis sympathetic cooling can prepare a molecular ion in its rovibrational quantum ground state, providing a method for state preparation for applications in molecular ion quantum logic.\nWhile collisions between the molecular ion and the cold atoms can cool the internal degrees of freedom, chemical reactions are also possible for electronically excited atoms.\nAs such, we study these excited-state atom--ion reactions at low temperature <1<1<1~K and develop tools to control these collisions.\nWe make the first experimental observation of reaction blockading, an effect that suppresses excited-state reactions at low temperature, and develop a method to reverse this suppression if desired with the addition of a catalyst laser, providing a means to optically control such reactions.Beyond its intended purpose of studying and achieving sympathetic cooling, we find that this apparatus is a powerful tool for chemical studies.By imaging the ions, we can observe reactions occurring one atom at a time.\nWe can precisely tune the collision energy or temperature down to the mK regime to as high as $\\sim$10~K using techniques described in this dissertation, allowing controlled interrogation of these low-temperature reactions.\nFurther, using lasers to address electronic transitions, we can precisely control the quantum state of the reactants, and we can measure the reaction products with the ToF-MS.\nA testament to the value of this apparatus is the study of BaOCa$^+$ described in this dissertation.\nUsing the tools of the MOTion trap, we were able to identify the production of BaOCa+^++, the first observation of a mixed hypermetallic oxide, and determine the path of reaction as BaOCH3+_3^+3+​ + Ca(4s4p4s4p4s4p~3PJ^3P_J3PJ​) rightarrow\\rightarrowrightarrow BaOCa+^++ + CH3_33​.In addition to developing control of these atom--ion interactions towards sympathetic cooling of molecular ions, we also work towards further developing new quantum logic schemes for molecular ions, such as dipolar quantum logic, dipole--phonon quantum logic (DPQL), and electric-field gradient gates (EGGs).Specifically, we propose a class of molecules particularly well-suited for DPQL, the alkaline earth monoxide cations, that can also be added to existing atomic ion experiments with minimal additional experimental complexity.\nWe further develop the techniques for DPQL and propose methods for single- and two-qubit gates, outlining a path towards universal quantum computation with molecular ions.
Using a laser-cooled ion trapping apparatus, we have investigated laser-induced chemical reactions between cold trapped Ba+{\mathrm{Ba}}^{+}Ba+ ions and several neutral molecular gases at room temperature, O2{\mathrm{O}}_{2}O2​, CO2\mathrm{C}{\mathrm{O}}_{2}CO2​, and N2O{\mathrm{N}}_{2}\mathrm{O}N2​O, leading to the production of cold trapped $(\ensuremath{\approx}20\phantom{\rule{0.3em}{0ex}}\mathrm{mK})$ BaO+\mathrm{Ba}{\mathrm{O}}^{+}BaO+ ions. The BaO+\mathrm{Ba}{\mathrm{O}}^{+}BaO+ ions were converted back to Ba+{\mathrm{Ba}}^{+}Ba+ ions via reaction with room-temperature CO. Reaction rates were determined by employing molecular dynamics simulations. The cold mixed-species ion ensembles produced were used for studying the efficiency of sympathetic cooling, by variation of the ratio of laser-cooled to sympathetically cooled ion numbers. In one extreme case, 20 laser-cooled 138Ba+^{138}\mathrm{Ba}^{+}138Ba+ ions were capable of maintaining the translational temperature of 120 sympathetically cooled barium isotopes (135−−137Ba+)(^{135--137}\mathrm{Ba}^{+})(135−−137Ba+) and 430 138Ba16O+^{138}\mathrm{Ba}^{16}{\mathrm{O}}^{+}138Ba16O+ molecules at approximately 25mK25\phantom{\rule{0.3em}{0ex}}\mathrm{mK}25mK.
Das Verhalten von kalten (15 µK) Calcium-Atomen in einer geeigneten optischen Dipolfalle wurde untersucht.Prozesse, die die Phasenraumdichte des in der Dipolfalle gespeicherten Calcium-Ensembles begrenzen, wurden identifiziert und untersucht.Zusammen mit der experimentell bestimmten Grundzustands-Streulänge wurden die Aussichten für die Realisierung eines Calcium Bose-Einstein-Kondensats erörtert.Die Dipolfalle wurde so konzipiert, dass ihr Betrieb mit der Laserkühlung auf dem schmalen Interkombinationsübergang 4s 2 1 S 0 → 4s4p 3 P 1 bei 657 nm verträglich ist.Atome, die in einer auf dem Interkombinationsübergang operierenden magneto-optischen Falle gekühlt und gespeichert werden, können nur begrenzt in die Dipolfalle transferiert werden, da das 657 nm Laserlicht zur Photoassoziation von Ca 2 -Molekülen führt, die aus der Dipolfalle verloren gehen.Die entsprechende Zweikörper-Verlustrate konnte zusammen mit der Einfangrate der Dipolfalle und den Verlustraten der magneto-optischen Falle in einem Modell erfaßt werden, das die Ladedynamik der Dipolfalle beschreibt.Eine maximale Steigerung der Phasenraumdichte des Calcium-Ensembles auf 0.045 konnte im Kreuzungsbereich zweier Dipolfallen erreicht werden.Der Transfer von Atomen aus einer Einzelfalle in den Kreuzungsbereich beider Fallen wird durch elastische Stöße hervorgerufen.Die Teilchenzahl im Kreuzungsbereich wird durch inelastische Dreikörper-Stöße begrenzt, deren Rate jedoch mehr als eine Größenordnung kleiner ist als die elastische Stoßrate.Die Ladedynamik des Kreuzungsbereichs wird durch ein Modell beschrieben, das die verschiedenen Raten berücksichtigt.Die Grundzustands-Streulänge wurde durch Photoassoziations-Spektroskopie unterhalb der 4s 2 1 S 0 + 4s4p 1 P 1 Asymptote bestimmt.Im Vergleich zu früheren Messungen erlaubten verbesserte experimentelle Bedingungen einen größeren Bereich von Kernabständen zu erfassen.Die damit verbundenen genaueren Messungen liefern nun einen Bereich der Streulänge zwischen 340a 0 und 700a 0 und lösen damit die Diskrepanz zwischen den Ergebnissen früherer Messungen.Als Ergebnis der Untersuchungen ist es nun möglich den experimentell aussichtsreichsten Weg für die Erzeugung eines Calcium Bose-Einstein-Kondensats aufzuzeigen, das zahlreiche neue und faszinierende Forschungsmöglichkeiten bietet.