Efficient rotational cooling of Coulomb-crystallized molecular ions by a helium buffer gas

Hansen, Anders Kragh; Versolato, Oscar; Kłosowski, Łukasz; Kristensen, Simon; Gingell, Alexander D.; Schwarz, Maria A.; Windberger, Alexander; Ullrich, J.; López‐Urrutia, J. R. Crespo; Drewsen, Michael

doi:10.1038/nature12996

Cited by 94 publications

(111 citation statements)

References 30 publications

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“…Co-trapping ions and atoms [6][7][8][9][10][11][12][13][14] widens the scope of inquiry to the two-particle asymptotic interaction. Among the different methods to cool trapped ions, cooling by elastic collisions with cold neutral atoms is arguably the most generic.…”

Section: Doimentioning

confidence: 99%

Collisional Cooling of Light Ions by Cotrapped Heavy Atoms

2017

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We experimentally demonstrate cooling of trapped ions by collisions with co-trapped, higher mass neutral atoms. It is shown that the lighter 39 K + ions, created by ionizing 39 K atoms in a magneto-optical trap (MOT), when trapped in an ion trap and subsequently allowed to cool by collisions with ultracold, heavier 85 Rb atoms in a MOT, exhibit a longer trap lifetime than without the localized 85 Rb MOT atoms. A similar cooling of trapped 85 Rb + ions by ultracold 133 Cs atoms in a MOT is also demonstrated in a different experimental configuration to validate this mechanism of ion cooling by localized and centered ultracold neutral atoms. Our results suggest that cooling of ions by localized cold atoms holds for any mass ratio, thereby enabling studies on a wider class of atom-ion systems irrespective of their masses. DOI:PACS numbers: 37.10.Rs, 37.10.Ty, 37.10.DeThe cooling and trapping of dilute gases of ions [1,2] and atoms [3] has led to unprecedented precision in spectroscopy [4] and the study of interacting many particle systems [5]. Co-trapping ions and atoms [6][7][8][9][10][11][12][13][14] widens the scope of inquiry to the two-particle asymptotic interaction. Among the different methods to cool trapped ions, cooling by elastic collisions with cold neutral atoms is arguably the most generic. Indeed, this has been extensively used in buffer gas cooling of relatively heavy ions by collisions with cold lower mass neutral atoms. However, the complementary phenomenon, that of cooling of low-mass ions by collisions with heavier neutral atoms, has never been demonstrated experimentally. This is partly because calculations show that trapped ions in a uniform buffer gas will heat up when the ratio of the atom mass ( ) to the ion mass ( ) exceeds a critical value [15][16][17][18]. In recent years, theoretical studies suggest a possible experimental resolution by using a localized ensemble of ultracold neutral atoms placed precisely at the centre of the ion trap [12,19].In ) we demonstrate cooling for, exceed the critical mass ratios (CMRs) [15][16][17][18] beyond which ion heating is predicted for uniform atomic gas densities. The experiment is consistent with our Monte Carlo (MC) simulations and other theoretical models [19] that consider collisions with centrally localized density (as opposed to uniform density) of cold atoms. We further demonstrate the competing ion heating mechanism due to collisions with the background gas vapour. The dependence of steady state ion temperature on the size of the cold atomic cloud is also established numerically. The present work lays the foundation for studies on a wider class of sympathetically cooled ion-atom mixtures and the resulting clarity may enable the realization of the few-partial-wave regime.Trapping and cooling ions and atoms. The conditions and mechanisms for trapping atoms and ions are different because the atom is neutral and the ion charged. Atom traps typically have small trap depths and use a combination of static magnetic and/or optical fields. Ions o...

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Section: Doimentioning

confidence: 99%

Collisional Cooling of Light Ions by Cotrapped Heavy Atoms

2017

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“…The new techniques have allowed for the sympathetic sideband cooling of motional modes to the ground state [6,7], preparation of the rotational ground state [8,9,10], and the non-destructive probing of rotational states [11]. The large rotational constants of diatomic hydrides [9,10,8,12] which slows blackbody rethermalization after rotational cooling combined with the availability of atomic coolants of similar masses make these molecular ions particularly well-suited to high precision spectroscopy measurements. Homonuclear diatomic molecular ions allow almost complete decoupling from blackbody radiation and are also a promising route towards tests of fundamental constants [13,14,15].…”

Section: Introductionmentioning

confidence: 99%

Vibronic Spectroscopy of Sympathetically Cooled CaH⁺

et al. 2016

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We report the measurement of the 1 1 Σ −→ 2 1 Σ transition of CaH + by resonance-enhanced photodissociation of CaH + that is co-trapped with laser-cooled Ca + . We observe four resonances that we assign to transitions from the vibrational v=0 ground state to the v =1-4 excited states based on theoretical predictions. A simple theoretical model that assumes instantaneous dissociation after resonant excitation yield results in good agreement with the observed spectral features except for the unobserved v =0 peak. The resolution of our experiment is limited by the mode-locked excitation laser, but this survey spectroscopy enables future rotationally resolved studies with applications in astrochemistry and precision measurement. 1

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“…The technique will unfold its full potential in high precision spectroscopy of narrow transitions using an independent spectroscopy laser. However, while in the present work black-body radiation probabilistically populates the detected state, precision spectroscopy will require efficient state preparation schemes 28,29 or ro-vibrational cooling techniques [7][8][9][10][11] . A combination of these powerful tools will enable the realization of optical clocks based on molecular ions approaching the 10 −18 level 30 , where the underlying clock transitions or a combination of transitions can be sensitive to variations of fundamental constants 3 , an electron electric dipole moment (eEDM) 5 or parity violation in chiral molecules.…”

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confidence: 96%

“…While the complexity of molecular structure facilitates these applications, the absence of cycling transitions poses a challenge for direct laser cooling 6 , quantum state control [7][8][9][10][11] , and detection. Previously employed state detection techniques based on photodissociation 12 or chemical reactions 13 are destructive and therefore inefficient, restricting the achievable resolution in laser spectroscopy.…”

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confidence: 99%

Non-destructive state detection for quantum logic spectroscopy of molecular ions

Wolf

Wan

Heip

et al. 2016

Nature

169

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Precision laser spectroscopy 1 of cold and trapped molecular ions is a powerful tool for fundamental physics, including the determination of fundamental constants 2 , the laboratory test for their possible variation 3,4 , and the search for a possible electric dipole moment of the electron 5 . While the complexity of molecular structure facilitates these applications, the absence of cycling transitions poses a challenge for direct laser cooling 6 , quantum state control [7][8][9][10][11] , and detection. Previously employed state detection techniques based on photodissociation 12 or chemical reactions 13 are destructive and therefore inefficient, restricting the achievable resolution in laser spectroscopy. Here we experimentally demonstrate nondestructive state detection of a single trapped molecular ion through its strong Coulomb coupling to a well-controlled co-trapped atomic ion. An algorithm based on a state-dependent optical dipole force 14 (ODF) changes the internal state of the atom conditioned on the internal state of the molecule. We show that individual quantum states in the molecular ion can be distinguished by their coupling strength to the ODF and observe black-body radiationinduced quantum jumps between rotational states of a single molecular ion. Using the detuning dependence of the state detection signal, we implement a variant of quantum logic spectroscopy 15,16 of a molecular resonance. The state detection technique we demonstrate is applicable to a wide range of molecular ions, enabling further applications in state-controlled quantum chemistry 17 and spectroscopic investigations of molecules serving as probes for interstellar clouds 18,19 .One of the salient features of trapped ion systems is that the universal Coulomb interaction allows strong coupling of diverse quantum objects, such as different species of atomic ions or atomic and molecular ions. Being able to perform quantum logic operations e.g. in the form of gates 14,20,21 between the quantum objects has proven a powerful tool for quantum information processing and quantum simulations in such systems. It also allows combining the advantages of different atomic species. Quantum logic spectroscopy is one such application in which the high degree of control achieved over selected atomic ions is extended to species over which such control is lacking 15,16 . Here, we demonstrate for the first time quantum logic operations between a single molecular ion and a co-trapped atomic ion, making a wide range of molecular ions accessible to this highlydeveloped toolbox. The presented technique allows the investigation of single molecules in a well isolated system avoiding disturbance from the environment, which is the limiting factor in other implementations of single molecule spectroscopy such as surface enhanced Raman spectroscopy (SERS) 22 Quantum logic operations between atoms are based on state dependent forces often induced by laser fields. The same approach is applicable to molecular ions. The coupling is now distributed over many ro-vibrat...

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Efficient rotational cooling of Coulomb-crystallized molecular ions by a helium buffer gas

Cited by 94 publications

References 30 publications

Collisional Cooling of Light Ions by Cotrapped Heavy Atoms

Collisional Cooling of Light Ions by Cotrapped Heavy Atoms

Vibronic Spectroscopy of Sympathetically Cooled CaH⁺

Non-destructive state detection for quantum logic spectroscopy of molecular ions

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Efficient rotational cooling of Coulomb-crystallized molecular ions by a helium buffer gas

Cited by 94 publications

References 30 publications

Collisional Cooling of Light Ions by Cotrapped Heavy Atoms

Collisional Cooling of Light Ions by Cotrapped Heavy Atoms

Vibronic Spectroscopy of Sympathetically Cooled CaH+

Non-destructive state detection for quantum logic spectroscopy of molecular ions

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Product

Resources

About

Vibronic Spectroscopy of Sympathetically Cooled CaH⁺