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

Japanese Journal of Applied Physics

All-diode-laser cooling of Sr + isotope ions for analytical applications

Kyunghun Jung, Kazuhiro Yamamoto, Yuta Yamamoto, Masabumi Miyabe, Ikuo Wakaida, Shuichi Hasegawa

Published May 23, 2017• 11 citations
Publisher

Abstract

Abstract Trapping and cooling of Sr + isotope ions by an all-diode-laser system has been demonstrated in order to develop a novel mass spectrometric technique in combination with ion trap-laser cooling. First, we constructed external cavity diode lasers and associated stabilization apparatus for laser cooling of Sr + ions. The transition frequencies confirmed by optogalvanic spectroscopy enabled successful cooling of 88 Sr + ions. An image of two trapped ions has been captured by CCD camera. Minor isotopes, 84 Sr + and 86 Sr + , were also cooled and trapped. From an analysis of the observed spectra of a string crystal of each isotope, the isotope shifts of the cooling transition (5s 2 S 1/2 → 5p 2 P 1/2 ) of Sr + ions were determined to be +371(8) MHz for Δν 84–88 and +169(8) MHz for Δν 86–88 . In the case of the repumping transition (4d 2 D 3/2 → 5p 2 P 1/2 ), Δν 84–88 and Δν 86–88 were measured to be −833(6) and −400(5) MHz, respectively. These values are in good agreement with previously reported values.

DOI
10.7567/jjap.56.062401

Related papers

Laser cooling and imaging of individual radioactive Sr+90 ions

Kyunghun Jung, Yoshihiro Iwata, Masabumi Miyabe +4 more

We have developed an apparatus integrating resonance-ionization, ion-trap, and laser-cooling techniques for an ultratrace radioactive isotope $^{90}\mathrm{Sr}$ analysis. Trapped $^{90}\mathrm{Sr}^{+}$ isotope ions were laser cooled, and their $4d\phantom{\rule{0.16em}{0ex}}^{2}D_{3/2}\ensuremath{\rightarrow}5p\phantom{\rule{0.16em}{0ex}}^{2}P_{1/2}$ transition isotope shift was experimentally measured to be $\ensuremath{-}281(17)$ MHz by comparing individual spectra of $^{88}\mathrm{Sr}^{+}$ and $^{90}\mathrm{Sr}^{+}$ ions. Crystallization of $^{90}\mathrm{Sr}^{+}$ was carried out using the resonance frequency value confirmed in our experiment, and then $^{90}\mathrm{Sr}^{+}$ individual ions were successfully observed.

Physical Review A•Oct 30, 2017•12 citations

Isotope shifts of natural Sr+ measured by laser fluorescence in a sympathetically cooled Coulomb crystal

B. Dubost, Romain Dubessy, Benjamin Szymanski +3 more

We measured by laser spectroscopy the isotope shifts between naturally occurring even isotopes of strontium ions for both the $5s\phantom{\rule{0.16em}{0ex}}{\phantom{\rule{0.16em}{0ex}}}^{2}{S}_{1/2}\ensuremath{\rightarrow}5p\phantom{\rule{0.16em}{0ex}}{\phantom{\rule{0.16em}{0ex}}}^{2}{P}_{1/2}$ (violet) and the $4d\phantom{\rule{0.16em}{0ex}}{\phantom{\rule{0.16em}{0ex}}}^{2}{D}_{3/2}\ensuremath{\rightarrow}5p\phantom{\rule{0.16em}{0ex}}{\phantom{\rule{0.16em}{0ex}}}^{2}{P}_{1/2}$ (infrared) dipole-allowed optical transitions. Fluorescence spectra were taken by simultaneous measurements on a two-component Coulomb crystal in a linear Paul trap containing ${10}^{3}$--${10}^{4}$ laser-cooled ${\mathrm{Sr}}^{+}$ ions. The isotope shifts are extracted from the experimental spectra by fitting the data with the analytical solution of the optical Bloch equations describing a three-level atom interacting with two laser beams. This technique allowed us to increase the precision with respect to previously reported data obtained by optogalvanic spectroscopy or fast atomic-beam techniques. The results for the $5s\phantom{\rule{0.16em}{0ex}}{\phantom{\rule{0.16em}{0ex}}}^{2}{S}_{1/2}\ensuremath{\rightarrow}5p\phantom{\rule{0.16em}{0ex}}{\phantom{\rule{0.16em}{0ex}}}^{2}{P}_{1/2}$ transition are ${\ensuremath{\nu}}_{88}\ensuremath{-}{\ensuremath{\nu}}_{84}=+378(4)$ MHz and ${\ensuremath{\nu}}_{88}\ensuremath{-}{\ensuremath{\nu}}_{86}=+170(3)$ MHz, in agreement with previously reported measurements. In the case of the previously unexplored $4d\phantom{\rule{0.16em}{0ex}}{\phantom{\rule{0.16em}{0ex}}}^{2}{D}_{3/2}\ensuremath{\rightarrow}5p\phantom{\rule{0.16em}{0ex}}{\phantom{\rule{0.16em}{0ex}}}^{2}{P}_{1/2}$ transition we find ${\ensuremath{\nu}}_{88}\ensuremath{-}{\ensuremath{\nu}}_{84}=\ensuremath{-}828(4)$ MHz and ${\ensuremath{\nu}}_{88}\ensuremath{-}{\ensuremath{\nu}}_{86}=\ensuremath{-}402(2)$ MHz. These results provide more data for stringent tests of theoretical calculations of the isotope shifts of alkali-metal-like atoms. Moreover, they simplify the identification and the addressing of ${\mathrm{Sr}}^{+}$ isotopes for ion frequency standards or quantum-information-processing applications in the case of multi-isotope ion strings.

arXiv:1402.3390•Physical Review A•Mar 7, 2014•12 citations

Repumping and spectroscopy of laser-cooled Sr atoms using the (5s5p)3P2–(5s4d)3D2transition

Pascal G. Mickelson, Y N Martinez de Escobar, P Anzel +5 more

We describe repumping and spectroscopy of laser-cooled strontium (Sr) atoms using the (5s5p) 3 P 2 –(5s4d) 3 D 2 transition. Atom number in a magneto-optical trap is enhanced by driving this transition because Sr atoms that have decayed into the (5s5p) 3 P 2 dark state are repumped back into the (5s 2 ) 1 S 0 ground state. Spectroscopy of 84 Sr, 86 Sr, 87 Sr and 88 Sr improves the value of the (5s5p) 3 P 2 –(5s4d) 3 D 2 transition frequency and determines the isotope shifts for the transition accurately enough to guide laser-cooling experiments with less abundant isotopes.

arXiv:0907.2270•Journal of Physics B Atomic Molecular and Optical Physics•Nov 18, 2009•45 citations

Sympathetic cooling in a multi-isotope Sr+Coulomb crystal

S. Removille, Quentin C. Glorieux, T. Coudreau +3 more

This paper reports on trapping and laser-cooling of singly-ionized strontium ions in a linear Paul trap. We demonstrate loading of large ion clouds containing as much as 106 ions and laser cooling down to the Coulomb crystal transition. We observe the spatial segregation of the different Sr+ isotopes due to the mass-dependent Paul trap stiffness. Sympathetic cooling of the different isotopes is demonstrated, either by laser-cooling of 88Sr+ (83% abundance) or of 86Sr+ (10% abundance). These demonstrations open the way to the use of a large ion Coulomb crystal for quantum optics and quantum information experiments, where the strong confinement, the long lifetime, and the absence of perturbation by cooling lasers are crucial.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Apr 30, 2010•1 citation

Development of diode and fiber laser sources for a Sr+trapped-ion optical frequency standard

G. P. Barwood, C. S. Edwards, Patrick Robert Gill +2 more

The development of an all-solid-state systems of lasers is described for the cooling and probing of strontium ions in a radio-frequency (rf) trap. The Sr+ ions created within the rf trap are laser cooled by repeated cycling on the 422 nm 2S1/2 - 2P1/2 resonance transition. The 422 nm light was generated from a single mode 70 mW 844 nm diode laser, whose output was frequency doubled to 422 nm in a KNbO3 crystal inside a resonant enhancement cavity. Decays from the Sr+ upper resonance level into the 2D3/2 metastable state remove ions from the cooling cycle. This loss was prevented by driving the 1092 nm 2D3/2 - 2P1/2 transition using a Nd3+-doped fiber laser, diode-pumped at 826 nm. The 2S1/2 - 2D5/2 optical 'clock' transition at 674 nm has a natural linewidth of 0.4 Hz and may be probed with an AlGaInP laser diode. The laser diodes at 844 nm and 674 nm are both collimated using a piezo-mounted GRIN rod which also provides longitudinal mode selection. The spectral output is optically narrowed using resonant optical feedback.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Apr 30, 1993•8 citations

Laser cooling and trapping of 224Ra+

Mingyu Fan, Roy Ready, H. Li +7 more

We report laser cooling and trapping of ${}^{224}{\mathrm{Ra}}^{+}$ ions. This was realized via two-step photoionization loading of radium into an ion trap. A robust source for $^{224}\mathrm{Ra}$ atoms, which have a 3.6-day half-life, was realized with an effusive oven containing $^{228}\mathrm{Th}$, which has a 1.9-yr half-life, which continuously generates $^{224}\mathrm{Ra}$ via its $\ensuremath{\alpha}$-decay. We characterized the efficacy of this source and found that after depleting built-up radium the thorium decay provides a continuous source of radium atoms suitable for ion trapping. The vacuum system has been sealed for more than 6 months and continues to trap ions on demand. We also report a measurement of the $^{224}\mathrm{Ra} 7{s}^{2}{\phantom{\rule{4pt}{0ex}}}^{1}{\mathrm{S}}_{0}\ensuremath{\rightarrow}7s7p{\phantom{\rule{4pt}{0ex}}}^{1}{\mathrm{P}}_{1}$ transition frequency: $621\phantom{\rule{0.16em}{0ex}}043\phantom{\rule{0.16em}{0ex}}830\ifmmode\pm\else\textpm\fi{}60$ MHz, which is helpful for efficient photoionization. With this measurement and previous isotope shift measurements we find that the frequency of the same transition in $^{226}\mathrm{Ra}$ is $621\phantom{\rule{0.16em}{0ex}}037\phantom{\rule{0.16em}{0ex}}830\ifmmode\pm\else\textpm\fi{}60$ MHz, which disagrees with the most precise measurement, $621\phantom{\rule{0.16em}{0ex}}038\phantom{\rule{0.16em}{0ex}}489\ifmmode\pm\else\textpm\fi{}15$ MHz, which is used for the recommended value in the National Institute of Standards and Technology Atomic Spectra Database.

arXiv:2308.00241•Physical Review Research•Dec 5, 2023•7 citations
Abstract Trapping and cooling of Sr + isotope ions by an all-diode-laser system has been demonstrated in order to develop a novel mass spectrometric technique in combination with ion trap-laser cooling. First, we constructed external cavity diode lasers and associated stabilization apparatus for laser cooling of Sr + ions. The transition frequencies confirmed by optogalvanic spectroscopy enabled successful cooling of 88 Sr + ions. An image of two trapped ions has been captured by CCD camera. Minor isotopes, 84 Sr + and 86 Sr + , were also cooled and trapped. From an analysis of the observed spectra of a string crystal of each isotope, the isotope shifts of the cooling transition (5s 2 S 1/2 → 5p 2 P 1/2 ) of Sr + ions were determined to be +371(8) MHz for Δν 84–88 and +169(8) MHz for Δν 86–88 . In the case of the repumping transition (4d 2 D 3/2 → 5p 2 P 1/2 ), Δν 84–88 and Δν 86–88 were measured to be −833(6) and −400(5) MHz, respectively. These values are in good agreement with previously reported values.
We have developed an apparatus integrating resonance-ionization, ion-trap, and laser-cooling techniques for an ultratrace radioactive isotope 90Sr^{90}\mathrm{Sr}90Sr analysis. Trapped 90Sr+^{90}\mathrm{Sr}^{+}90Sr+ isotope ions were laser cooled, and their $4d\phantom{\rule{0.16em}{0ex}}^{2}D_{3/2}\ensuremath{\rightarrow}5p\phantom{\rule{0.16em}{0ex}}^{2}P_{1/2}$ transition isotope shift was experimentally measured to be $\ensuremath{-}281(17)$ MHz by comparing individual spectra of 88Sr+^{88}\mathrm{Sr}^{+}88Sr+ and 90Sr+^{90}\mathrm{Sr}^{+}90Sr+ ions. Crystallization of 90Sr+^{90}\mathrm{Sr}^{+}90Sr+ was carried out using the resonance frequency value confirmed in our experiment, and then 90Sr+^{90}\mathrm{Sr}^{+}90Sr+ individual ions were successfully observed.
We measured by laser spectroscopy the isotope shifts between naturally occurring even isotopes of strontium ions for both the $5s\phantom{\rule{0.16em}{0ex}}{\phantom{\rule{0.16em}{0ex}}}^{2}{S}_{1/2}\ensuremath{\rightarrow}5p\phantom{\rule{0.16em}{0ex}}{\phantom{\rule{0.16em}{0ex}}}^{2}{P}_{1/2}$ (violet) and the $4d\phantom{\rule{0.16em}{0ex}}{\phantom{\rule{0.16em}{0ex}}}^{2}{D}_{3/2}\ensuremath{\rightarrow}5p\phantom{\rule{0.16em}{0ex}}{\phantom{\rule{0.16em}{0ex}}}^{2}{P}_{1/2}$ (infrared) dipole-allowed optical transitions. Fluorescence spectra were taken by simultaneous measurements on a two-component Coulomb crystal in a linear Paul trap containing 103{10}^{3}103--104{10}^{4}104 laser-cooled Sr+{\mathrm{Sr}}^{+}Sr+ ions. The isotope shifts are extracted from the experimental spectra by fitting the data with the analytical solution of the optical Bloch equations describing a three-level atom interacting with two laser beams. This technique allowed us to increase the precision with respect to previously reported data obtained by optogalvanic spectroscopy or fast atomic-beam techniques. The results for the $5s\phantom{\rule{0.16em}{0ex}}{\phantom{\rule{0.16em}{0ex}}}^{2}{S}_{1/2}\ensuremath{\rightarrow}5p\phantom{\rule{0.16em}{0ex}}{\phantom{\rule{0.16em}{0ex}}}^{2}{P}_{1/2}$ transition are ${\ensuremath{\nu}}_{88}\ensuremath{-}{\ensuremath{\nu}}_{84}=+378(4)$ MHz and ${\ensuremath{\nu}}_{88}\ensuremath{-}{\ensuremath{\nu}}_{86}=+170(3)$ MHz, in agreement with previously reported measurements. In the case of the previously unexplored $4d\phantom{\rule{0.16em}{0ex}}{\phantom{\rule{0.16em}{0ex}}}^{2}{D}_{3/2}\ensuremath{\rightarrow}5p\phantom{\rule{0.16em}{0ex}}{\phantom{\rule{0.16em}{0ex}}}^{2}{P}_{1/2}$ transition we find ${\ensuremath{\nu}}_{88}\ensuremath{-}{\ensuremath{\nu}}_{84}=\ensuremath{-}828(4)$ MHz and ${\ensuremath{\nu}}_{88}\ensuremath{-}{\ensuremath{\nu}}_{86}=\ensuremath{-}402(2)$ MHz. These results provide more data for stringent tests of theoretical calculations of the isotope shifts of alkali-metal-like atoms. Moreover, they simplify the identification and the addressing of Sr+{\mathrm{Sr}}^{+}Sr+ isotopes for ion frequency standards or quantum-information-processing applications in the case of multi-isotope ion strings.
We describe repumping and spectroscopy of laser-cooled strontium (Sr) atoms using the (5s5p) 3 P 2 –(5s4d) 3 D 2 transition. Atom number in a magneto-optical trap is enhanced by driving this transition because Sr atoms that have decayed into the (5s5p) 3 P 2 dark state are repumped back into the (5s 2 ) 1 S 0 ground state. Spectroscopy of 84 Sr, 86 Sr, 87 Sr and 88 Sr improves the value of the (5s5p) 3 P 2 –(5s4d) 3 D 2 transition frequency and determines the isotope shifts for the transition accurately enough to guide laser-cooling experiments with less abundant isotopes.
This paper reports on trapping and laser-cooling of singly-ionized strontium ions in a linear Paul trap. We demonstrate loading of large ion clouds containing as much as 106 ions and laser cooling down to the Coulomb crystal transition. We observe the spatial segregation of the different Sr+ isotopes due to the mass-dependent Paul trap stiffness. Sympathetic cooling of the different isotopes is demonstrated, either by laser-cooling of 88Sr+ (83% abundance) or of 86Sr+ (10% abundance). These demonstrations open the way to the use of a large ion Coulomb crystal for quantum optics and quantum information experiments, where the strong confinement, the long lifetime, and the absence of perturbation by cooling lasers are crucial.
The development of an all-solid-state systems of lasers is described for the cooling and probing of strontium ions in a radio-frequency (rf) trap. The Sr+ ions created within the rf trap are laser cooled by repeated cycling on the 422 nm 2S1/2 - 2P1/2 resonance transition. The 422 nm light was generated from a single mode 70 mW 844 nm diode laser, whose output was frequency doubled to 422 nm in a KNbO3 crystal inside a resonant enhancement cavity. Decays from the Sr+ upper resonance level into the 2D3/2 metastable state remove ions from the cooling cycle. This loss was prevented by driving the 1092 nm 2D3/2 - 2P1/2 transition using a Nd3+-doped fiber laser, diode-pumped at 826 nm. The 2S1/2 - 2D5/2 optical 'clock' transition at 674 nm has a natural linewidth of 0.4 Hz and may be probed with an AlGaInP laser diode. The laser diodes at 844 nm and 674 nm are both collimated using a piezo-mounted GRIN rod which also provides longitudinal mode selection. The spectral output is optically narrowed using resonant optical feedback.
We report laser cooling and trapping of 224Ra+{}^{224}{\mathrm{Ra}}^{+}224Ra+ ions. This was realized via two-step photoionization loading of radium into an ion trap. A robust source for 224Ra^{224}\mathrm{Ra}224Ra atoms, which have a 3.6-day half-life, was realized with an effusive oven containing 228Th^{228}\mathrm{Th}228Th, which has a 1.9-yr half-life, which continuously generates 224Ra^{224}\mathrm{Ra}224Ra via its $\ensuremath{\alpha}$-decay. We characterized the efficacy of this source and found that after depleting built-up radium the thorium decay provides a continuous source of radium atoms suitable for ion trapping. The vacuum system has been sealed for more than 6 months and continues to trap ions on demand. We also report a measurement of the $^{224}\mathrm{Ra} 7{s}^{2}{\phantom{\rule{4pt}{0ex}}}^{1}{\mathrm{S}}_{0}\ensuremath{\rightarrow}7s7p{\phantom{\rule{4pt}{0ex}}}^{1}{\mathrm{P}}_{1}$ transition frequency: $621\phantom{\rule{0.16em}{0ex}}043\phantom{\rule{0.16em}{0ex}}830\ifmmode\pm\else\textpm\fi{}60$ MHz, which is helpful for efficient photoionization. With this measurement and previous isotope shift measurements we find that the frequency of the same transition in 226Ra^{226}\mathrm{Ra}226Ra is $621\phantom{\rule{0.16em}{0ex}}037\phantom{\rule{0.16em}{0ex}}830\ifmmode\pm\else\textpm\fi{}60$ MHz, which disagrees with the most precise measurement, $621\phantom{\rule{0.16em}{0ex}}038\phantom{\rule{0.16em}{0ex}}489\ifmmode\pm\else\textpm\fi{}15$ MHz, which is used for the recommended value in the National Institute of Standards and Technology Atomic Spectra Database.