Measurement of a Large Chemical Reaction Rate between Ultracold Closed-Shell<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi>Ca</mml:mi><mml:mprescripts /><mml:none /><mml:mn>40</mml:mn></mml:mmultiscripts></mml:math>Atoms and Open-Shell<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mmultiscripts><mml:mi>Yb</mml:mi><mml:none /><mml:mo>+</mml:mo><mml:mprescripts /><mml:none /><mml:mn>174</mml:mn></mml:mmultiscripts></mml:mat

Rellergert, Wade G.; Sullivan, Scott T.; Kotochigova, Svetlana; Petrov, A. N.; Chen, Kuang; Schowalter, Steven J.; Hudson, Eric R.

doi:10.1103/physrevlett.107.243201

Cited by 138 publications

(108 citation statements)

References 31 publications

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“…Because the ion is colliding in highly excited electronic states, such as P 1/2 and D 3/2 with internal energies of ≈3 eV, this suggests a mostly radiative decay into the ground state S 1/2 . We have ruled out that the reoccurrence events are linked to the dissociation of a potential molecular ion in a secondary collision with neutral atoms 12 .…”

Section: Of S- P- D- and D[3/2]-statesmentioning

confidence: 99%

“…Experimentally, reactive Langevin collisions in the polarization potential have been investigated in ground state collisions [7][8][9][10]12,18 , which have exhibited relatively low rates for inelastic collisions, except for resonant charge exchange 7 . Recently, the first steps towards understanding reactive collisions in excited electronic states have been made using large ion crystals [11][12][13] , suggesting either a dominant contribution from very shortlived electronic states in the Rb + Ca + system 11 or, contrarily, a negligible contribution from excited state collisions in the Ca + Yb + system 12 . Here, we demonstrate how control over the internal electronic state of a single ion and the hyperfine state of neutral atoms can be employed to tune cold exchange reaction processes.…”

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confidence: 99%

“…More subtle effects, such as the hyperfine interaction, which may lead to atom-ion Feshbach resonances, are not included in the polarization potential and have been investigated only theoretically so far 17 . Experimentally, reactive Langevin collisions in the polarization potential have been investigated in ground state collisions [7][8][9][10]12,18 , which have exhibited relatively low rates for inelastic collisions, except for resonant charge exchange 7 . Recently, the first steps towards understanding reactive collisions in excited electronic states have been made using large ion crystals 11-13 , suggesting either a dominant contribution from very shortlived electronic states in the Rb + Ca + system 11 or, contrarily, a negligible contribution from excited state collisions in the Ca + Yb + system 12 .…”

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Controlling chemical reactions of a single particle

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. For these studies, single particles provide a clean and well-controlled experimental system. Here, we report on the experimental tuning of the exchange reaction rates of a single trapped ion with ultracold neutral atoms by exerting control over both their quantum states. We observe the influence of the hyperfine interaction on chemical reaction rates and branching ratios, and monitor the kinematics of the reaction products. These investigations advance chemistry with single trapped particles towards achieving quantum-limited control of chemical reactions and indicate limits for buffer-gas cooling of single-ion clocks.The full control over all quantum mechanical degrees of freedom of a chemical reaction allows the identification of fundamental interaction processes and the steering of chemical reactions. This task is often complicated in heteronuclear systems by a multitude of possible reaction channels, which make theoretical treatments very challenging. Therefore, focussing on the best-controlled experimental conditions, such as using state-selected single particles and low temperatures, is crucial for the investigation of chemical processes at the most elementary level. The hybrid system of trapped atoms and ions offers key advantages in this undertaking. On the one hand, ion traps offer a large potential well depth to trap the reaction products for precision manipulation and investigation. On the other hand, contrary to pure ionic systems, there is no Coulomb barrier between the particles to fundamentally prevent chemical reactions at low temperatures. Therefore, the efforts to control the motional degrees of freedom of one 4-6 and both 7-13 reactants in hybrid atom-ion systems have paved new ways towards cold chemistry. The yet missing component is the simultaneous control of the internal degrees of freedom.The interaction between an ion and a neutral atom at long distances is dominated by the attractive polarization interaction potential V (r), which is of the formHere, C 4 = α 0 q 2 /(4π 0 ) 2 is proportional to the neutral particle polarizability α 0 , q is the charge of the ion, 0 is the vacuum permittivity, and r is the internuclear separation. Inelastic collisions take place at short internuclear distances. In the cold, semiclassical regime this requires collision energies above the centrifugal barrier [14][15][16] . Such processes are referred to as Langevin-type collisions and happen, even for cold collisions 7,9 , at an energyindependent rate γ Langevin = 2π √ C 4 /µ n a . Here µ is the reduced mass of the collision partners and n a is the neutral atom density.Cavendish Laboratory, University of Cambridge, JJ Thomson Avenue, Cambridge CB3 0HE, UK. *e-mail: cs540@cam.ac.uk. More subtle effects, such as the hyperfine interaction, which may lead to atom-ion Feshbach resonances, are not included in the polarization potential and have been investigated only theoretically so far 17 . Experimentally, reactive Langevin collisions in the polarization potential have been investigated in ground state collisi...

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Section: Of S- P- D- and D[3/2]-statesmentioning

confidence: 99%

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confidence: 99%

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confidence: 99%

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Controlling chemical reactions of a single particle

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“…A mixed system of cooled and trapped atoms and trapped ions [1][2][3][4][5][6] paves the way for ion assisted cold chemistry [7][8][9][10] and many novel body studies 11 . As the mechanisms for trapping ions and atoms differ, so do their ener gies near the bottom of their respective traps.…”

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Cooling and stabilization by collisions in a mixed ion–atom system

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In mixed systems of trapped ions and cold atoms, the ions and atoms can coexist at different temperatures. This is primarily due to their different trapping and cooling mechanisms. The key questions of how ions can cool collisionally with cold atoms and whether the combined system allows stable coexistence, need to be answered. Here we experimentally demonstrate that rubidium ions cool in contact with magneto-optically trapped rubidium atoms, contrary to the general experimental expectation of ion heating. The cooling process is explained theoretically and substantiated with numerical simulations, which include resonant charge exchange collisions. The mechanism of single collision swap cooling of ions with atoms is discussed. Finally, it is experimentally and numerically demonstrated that the combined ion-atom system is intrinsically stable, which is critical for future cold chemistry experiments with such systems.

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“…While some of the systems do lie in the unstable region, those experiments are able to operate by using some combination of a low buffer gas density, laser cooling of trapped ions, and a multipole trap [35]. [72]; Rb-Yb + , Bonn [73] and Ulm [74]; Rb-Ba + , Ulm [74] and Basel [75]; Ca-Yb + , UCLA [76] and Ca-BaCl + , UCLA [41]; Rb-Ca + , Basel [44]; Ca-Ba + , UCLA [45]; Na-Na + UCONN [77]; Rb-OH − , Innsbruck [78] ; Rb-N + 2 , Basel [18]; Rb-Rb + Bangalore [79] and Rb-Sr + , Weizmann [34] A further peculiarity of sympathetic cooling in an ion trap is manifested in the steadystate energy distribution of the ion, which features a power-law tail, of the form P(E) ∝ E −(ν+1) , due to the random amplification of the ion energy by collisions; it is for this reason that temperature is an ill-defined quantity for the ion and we instead refer to the steady-state (average) energy in the above. In [28] a simplified model is considered to gain a qualitative understanding of how this distribution arises.…”

Section: Relaxation Of a Single Ion In A Buffer Gasmentioning

confidence: 99%