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

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)

Stabilization of a specific configuration of a two-species ion chain by selective vibrational excitation

Kazuhiro Hayasaka

Published May 1, 2011• 0 citations
Publisher

Abstract

Two-species ion chains supply an access to the ions, which cannot be laser-cooled alone. The ions are cooled by coulomb coupling with laser-cooled ions, and manifest themselves as dark sites in the coulomb crystal. Localization within an optical wavelength can also be achieved. The applications include an optical clock based on atomic ions with a relative uncertainty in the order of 10−18[1] and high-resolution vibrational spectroscopy of a molecular ion with an accuracy of 2ppb[2]. We report on an experimental study of stabilizing a selected configuration of an ion chain consisting of115In+and40Ca+. Unwanted configurations are destabilized by applying amplitude modulation onto the Ca+laser-cooling beam at frequencies resonant to the vibrational mode. As a result only the target configuration survives.

DOI
10.1109/cleoe.2011.5943295

Related papers

Rotational cooling of molecular ions through laser-induced coupling to the collective modes of a two-ion Coulomb crystal

Ivan R. Vogelius, Lars Bojer Madsen, Michael Drewsen

We show that the rotational degree of freedom of a polar heteronuclear molecular ion can be cooled through an optical coupling to the collective motional modes of the molecular ion and a simultaneously trapped and laser cooled atomic ion. Since the dissipative part of the rotational cooling is realized through laser cooling of the two-ion systems motional modes, the scheme should be applicable to a large range of molecules. As a test case for our cooling scheme we consider rotational cooling of a MgH + ion trapped with a laser cooled 40 Ca + ion.

Journal of Physics B Atomic Molecular and Optical Physics•Sep 25, 2006•18 citations

Spectroscopy of Single Trapped Ions and Application to Frequency Standards

HERBERT WALTHER

Single ions trapped and laser cooled provide ideal objects for high resolution spectroscopy and frequency standards. For the latter purpose we are investigating the 5s2 1S0 → 5s5p 3P0 transition of In+. With a natural linewidth of only 1.1 Hz this resonance offers very high resolution and is highly immune to frequency shifts due to external electromagnetic fields, because it connects two levels with vanishing electronic magnetic momenta [1]. The wavelength of this clock transition is 236.5 nm and is technically very convenient, since it coincides with the fourth harmonic of the 946 nm Nd:YAG laser line. So this intrinsically frequency stable solid-state laser can be used to excite the transition [2]. For laser cooling and fluorescence detection of the indium ion the 5s2 1So -> 5s5p 3P1 transition at 230.6 nm can be employed. The use of the relatively narrow intercombination line for laser cooling allows us to study optical sideband cooling in the strong binding regime, where the oscillation frequencies of the ion in the trap (around 1 MHz) are larger than the optical linewidth of 360 kHz. In this parameter range laser cooling is possible to the quantum ground state of the vibrational motion in the trap corresponding to a temperature of roughly 100 μK. The same low temperature was obtained with sideband cooling of a small Coulomb crystal consisting of two ions, creating an interesting new quantum few-particle system.

Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)•Jan 1, 1998•0 citations

Spectroscopy of molecular ions in Coulomb crystals

René Rugango

This thesis presents the results of my graduate work which has concentrated on applying laser-cooling techniques to molecular ions, specifically CaH⁺ and BH⁺ ions for the study of their rovibronic spectroscopy. The goal of my research has been to control external and internal degrees of freedom of these two ions. Each of these molecules is spectroscopically appealing in its own right. For starters, CaH⁺ has been identified as a potential system for the test for the time variation of fundamental constants, and it's also been speculated to be in space. BH⁺ has a nearly diagonal Franck-Condon structure, and could be directly laser-cooled using only a few lasers. This structure makes it a good candidate for the cooling of internal molecular degrees of freedom. Each of the experiments described in this review involves the trapping and laser-cooling of ions. We cool the molecular ions sympathetically with laser-cooled Ca⁺. The probing techniques used to collect data are mainly: laser induced fluorescence, mass spectrometry, and resonance-enhanced multi-photon dissociation (REMPD). We have demonstrated the ground state sympathetic cooling of CaH⁺ ion to less than 16 $\\mu$K, and we have used to REMPD to measure for the first time four vibronic transitions in CaH⁺ ions. Together, these results are important for future quantum logic experiments on this molecule. Furthermore, we have also made some progress towards trapping and cooling BH⁺ ions by first trapping B⁺ ions with Ca⁺ ions. We use the motional resonance method to detect the B⁺ ions, which can be reacted with H atoms to produce the molecular ions. Following the measurement of the vibronic spectrum of CaH⁺, we have narrowed the linewidth of the laser source to resolve rotational lines.

•Nov 17, 2016•0 citations

Spectroscopy of Molecular Ions in Coulomb Crystals

Aaron T. Calvin, Kenneth R. Brown

In this Perspective, we examine the use of laser-cooled atomic ions and sympathetically cooled molecular ions in Coulomb crystals for molecular spectroscopy. Coulomb crystals are well-isolated environments that provide localization and long storage times for sensitive measurements of weak signals and cold temperatures for precise spectroscopy. Coulomb crystals of molecular and atomic ions enable the detection of single-photon molecular ion transitions at a range of wavelengths by a change in atomic ion fluorescence at visible wavelengths. We give an overview of the state of the art from action spectroscopy to quantum logic spectroscopy for a wide range of molecular transitions from rotational sublevels separated by 10 –7 cm –1 to rovibronic transitions at 25 000 cm –1 . We emphasize how this system allows for unparalleled control of the molecular ion state for precision spectroscopy with applications in astrochemistry and fundamental physics. We conclude with an outlook of the use of this control in cold molecular ion reactions.

The Journal of Physical Chemistry Letters•Sep 13, 2018•19 citations

Sympathetic cooling and crystallization of ions in a linear Paul trap

Michael Drewsen, Paul David Bowe, Liv Hornekær +3 more

Coulomb crystals, containing up to a few hundred ions of which more than 50% were cooled sympathetically by the Coulomb interaction with laser cooled Mg+ ions, have been produced in a linear Paul trap. By controlling the balance of the radiation pressure from the two cooling lasers, the Coulomb crystals could be segregated according to ion species. Previous studies of ion crystals and molecular dynamics simulations suggest that the temperature may be around 10 mK or lower. The obtained results indicate that a wide range of atomic and molecular ions, which due to their internal structures are not amenable to direct laser cooling, can be effectively cooled and localized (crystallized) in linear Paul traps. For high resolution spectroscopy of such ions this may turn out to be very useful.

AIP conference proceedings•Jan 1, 1999•0 citations

Quantum memory for light based on ion coulomb crystals

Peter F. Herskind, A. Mortensen, E.S. Nielsen +2 more

The authors report on the stored light in an ion Coulomb crystal coupled to a relatively low finesse optical resonator. A two-species ion Coulomb crystal is employed in a linear Paul trap, where the laser cooled heavier ion-component sympathetically cools the lighter ion-component.

European Quantum Electronics Conference (EQEC)•Jan 18, 2006•0 citations
Two-species ion chains supply an access to the ions, which cannot be laser-cooled alone. The ions are cooled by coulomb coupling with laser-cooled ions, and manifest themselves as dark sites in the coulomb crystal. Localization within an optical wavelength can also be achieved. The applications include an optical clock based on atomic ions with a relative uncertainty in the order of 10−18[1] and high-resolution vibrational spectroscopy of a molecular ion with an accuracy of 2ppb[2]. We report on an experimental study of stabilizing a selected configuration of an ion chain consisting of115In+and40Ca+. Unwanted configurations are destabilized by applying amplitude modulation onto the Ca+laser-cooling beam at frequencies resonant to the vibrational mode. As a result only the target configuration survives.
We show that the rotational degree of freedom of a polar heteronuclear molecular ion can be cooled through an optical coupling to the collective motional modes of the molecular ion and a simultaneously trapped and laser cooled atomic ion. Since the dissipative part of the rotational cooling is realized through laser cooling of the two-ion systems motional modes, the scheme should be applicable to a large range of molecules. As a test case for our cooling scheme we consider rotational cooling of a MgH + ion trapped with a laser cooled 40 Ca + ion.
Single ions trapped and laser cooled provide ideal objects for high resolution spectroscopy and frequency standards. For the latter purpose we are investigating the 5s2 1S0 → 5s5p 3P0 transition of In+. With a natural linewidth of only 1.1 Hz this resonance offers very high resolution and is highly immune to frequency shifts due to external electromagnetic fields, because it connects two levels with vanishing electronic magnetic momenta [1]. The wavelength of this clock transition is 236.5 nm and is technically very convenient, since it coincides with the fourth harmonic of the 946 nm Nd:YAG laser line. So this intrinsically frequency stable solid-state laser can be used to excite the transition [2]. For laser cooling and fluorescence detection of the indium ion the 5s2 1So -> 5s5p 3P1 transition at 230.6 nm can be employed. The use of the relatively narrow intercombination line for laser cooling allows us to study optical sideband cooling in the strong binding regime, where the oscillation frequencies of the ion in the trap (around 1 MHz) are larger than the optical linewidth of 360 kHz. In this parameter range laser cooling is possible to the quantum ground state of the vibrational motion in the trap corresponding to a temperature of roughly 100 μK. The same low temperature was obtained with sideband cooling of a small Coulomb crystal consisting of two ions, creating an interesting new quantum few-particle system.
This thesis presents the results of my graduate work which has concentrated on applying laser-cooling techniques to molecular ions, specifically CaH⁺ and BH⁺ ions for the study of their rovibronic spectroscopy. The goal of my research has been to control external and internal degrees of freedom of these two ions. Each of these molecules is spectroscopically appealing in its own right. For starters, CaH⁺ has been identified as a potential system for the test for the time variation of fundamental constants, and it's also been speculated to be in space. BH⁺ has a nearly diagonal Franck-Condon structure, and could be directly laser-cooled using only a few lasers. This structure makes it a good candidate for the cooling of internal molecular degrees of freedom. Each of the experiments described in this review involves the trapping and laser-cooling of ions. We cool the molecular ions sympathetically with laser-cooled Ca⁺. The probing techniques used to collect data are mainly: laser induced fluorescence, mass spectrometry, and resonance-enhanced multi-photon dissociation (REMPD). We have demonstrated the ground state sympathetic cooling of CaH⁺ ion to less than 16 mu\\mumuK, and we have used to REMPD to measure for the first time four vibronic transitions in CaH⁺ ions. Together, these results are important for future quantum logic experiments on this molecule. Furthermore, we have also made some progress towards trapping and cooling BH⁺ ions by first trapping B⁺ ions with Ca⁺ ions. We use the motional resonance method to detect the B⁺ ions, which can be reacted with H atoms to produce the molecular ions. Following the measurement of the vibronic spectrum of CaH⁺, we have narrowed the linewidth of the laser source to resolve rotational lines.
In this Perspective, we examine the use of laser-cooled atomic ions and sympathetically cooled molecular ions in Coulomb crystals for molecular spectroscopy. Coulomb crystals are well-isolated environments that provide localization and long storage times for sensitive measurements of weak signals and cold temperatures for precise spectroscopy. Coulomb crystals of molecular and atomic ions enable the detection of single-photon molecular ion transitions at a range of wavelengths by a change in atomic ion fluorescence at visible wavelengths. We give an overview of the state of the art from action spectroscopy to quantum logic spectroscopy for a wide range of molecular transitions from rotational sublevels separated by 10 –7 cm –1 to rovibronic transitions at 25 000 cm –1 . We emphasize how this system allows for unparalleled control of the molecular ion state for precision spectroscopy with applications in astrochemistry and fundamental physics. We conclude with an outlook of the use of this control in cold molecular ion reactions.
Coulomb crystals, containing up to a few hundred ions of which more than 50% were cooled sympathetically by the Coulomb interaction with laser cooled Mg+ ions, have been produced in a linear Paul trap. By controlling the balance of the radiation pressure from the two cooling lasers, the Coulomb crystals could be segregated according to ion species. Previous studies of ion crystals and molecular dynamics simulations suggest that the temperature may be around 10 mK or lower. The obtained results indicate that a wide range of atomic and molecular ions, which due to their internal structures are not amenable to direct laser cooling, can be effectively cooled and localized (crystallized) in linear Paul traps. For high resolution spectroscopy of such ions this may turn out to be very useful.