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:2308.00241 · Physical Review Research

Laser cooling and trapping of 224Ra+

Mingyu Fan, Roy Ready, H. Li, Spencer Kofford, Robert Kwapisz, C. A. Holliman, M. S. Ladabaum, Alyssa Gaiser, Justin R. Griswold, Andrew M. Jayich

Published Dec 5, 2023• 7 citations
arXivHTMLPDF

Abstract

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.

DOI
10.1103/physrevresearch.5.043201

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

Measurement of $7p\ ^2P_{1/2}^o$ branching fractions with laser-cooled $^{226}\mathrm{Ra}^+$

Mingyu Fan, C. A. Holliman, A. L. Wang +1 more

The unstable radium nucleus is appealing for probing new physics due to its high mass, octupole deformation and energy level structure. Ion traps, with long hold times and low particle numbers, are excellent for work with radioactive species, such as radium and radium-based molecular ions, where low activity, and hence low total numbers, is desirable. We address the challenges associated with the lack of stable isotopes in a table-top experiment with a low-activity ($\sim 10 \mu\mathrm{Ci}$) source where we laser-cool radium ions to form radium Wigner crystals. With a laser-cooled radium ion we measured the $7p ^2P_{1/2}^o$ state's branching fractions to the ground state, $7s ^2S_{1/2}$, and a metastable excited state, $6d ^2D_{3/2}$, to be $p=0.9104(7)$ and $0.0896(7)$, respectively. With a nearby tellurium reference line we measured the $7s ^2S_{1/2} \rightarrow 7p ^2P_{1/2}^o$ transition frequency, 640.09663(6) THz.

•Jan 28, 2019•0 citations

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

Kyunghun Jung, Kazuhiro Yamamoto, Yuta Yamamoto +3 more

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.

Japanese Journal of Applied Physics•May 23, 2017•11 citations

Laser Cooling of Radium Ions

Mingyu Fan, C. A. Holliman, A. L. Wang +1 more

The unstable radium nucleus is appealing for probing new physics due to its high mass, octupole deformation, and energy level structure. Ion traps, with long hold times and low particle numbers, are excellent for work with radioactive species, such as radium and radium-based molecular ions, where low activity, and hence low total numbers, is desirable. We address the challenges associated with the lack of stable isotopes in a tabletop experiment with a low-activity (∼10 μCi) source where we laser-cool trapped radium ions. With a laser-cooled radium ion we measured the 7p^{2}P_{1/2}^{o} state's branching fractions to the ground state, 7s^{2}S_{1/2}, and a metastable excited state, 6d^{2}D_{3/2}, to be p=0.9104(7) and 0.0896(7), respectively. With a nearby tellurium reference line we measured the 7s^{2}S_{1/2}→7p^{2}P_{1/2}^{o} transition frequency, 640.096 63(6) THz.

arXiv:1901.09882•Physical Review Letters•Jun 7, 2019•28 citations

Laser cooling and quantum jumps of a single indium ion

E. Peik, Guenter Hollemann, HERBERT WALTHER

We performed laser spectroscopy of ${\mathrm{In}}^{+}$ ions stored in a radio-frequency trap. The 5${\mathit{s}}^{2}$ $^{1}$${\mathit{S}}_{0}$\ensuremath{\rightarrow}5s5p $^{3}$${\mathit{P}}_{1}$ transition at 230.6 nm was excited and its hyperfine splitting and isotope shift have been measured. The lifetime of the $^{3}$${\mathit{P}}_{1}$ state was measured using intensity modulated laser excitation: \ensuremath{\tau}${(}^{3}$${\mathit{P}}_{1}$)=0.44(4) \ensuremath{\mu}s. A single indium ion was laser cooled using this intercombination line and dark periods in the fluorescence were observed when the metastable $^{3}$${\mathit{P}}_{0}$ state was populated by a magnetic dipole decay from $^{3}$${\mathit{P}}_{1}$. The radiative lifetime of the forbidden transition $^{3}$${\mathit{P}}_{0}$${\ensuremath{\rightarrow}}^{1}$${\mathit{S}}_{0}$ was determined from the duration of the dark periods: \ensuremath{\tau}${(}^{3}$${\mathit{P}}_{0}$)=0.14(2) s. This value is compared to calculations based on perturbation theory. Prospects for an optical frequency standard using the narrow 5${\mathit{s}}^{2}$ $^{1}$${\mathit{S}}_{0}$\ensuremath{\rightarrow}5s5p $^{3}$${\mathit{P}}_{0}$ resonance at 236.5 nm of a single laser-cooled indium ion are discussed.

Physical Review A•Jan 1, 1994•104 citations

Laser cooling and quantum jumps of a single indium ion

E. Peik, Guenter Hollemann, HERBERT WALTHER

We performed laser spectroscopy of ${\mathrm{In}}^{+}$ ions stored in a radio-frequency trap. The 5${\mathit{s}}^{2}$ $^{1}$${\mathit{S}}_{0}$\ensuremath{\rightarrow}5s5p $^{3}$${\mathit{P}}_{1}$ transition at 230.6 nm was excited and its hyperfine splitting and isotope shift have been measured. The lifetime of the $^{3}$${\mathit{P}}_{1}$ state was measured using intensity modulated laser excitation: \ensuremath{\tau}${(}^{3}$${\mathit{P}}_{1}$)=0.44(4) \ensuremath{\mu}s. A single indium ion was laser cooled using this intercombination line and dark periods in the fluorescence were observed when the metastable $^{3}$${\mathit{P}}_{0}$ state was populated by a magnetic dipole decay from $^{3}$${\mathit{P}}_{1}$. The radiative lifetime of the forbidden transition $^{3}$${\mathit{P}}_{0}$${\ensuremath{\rightarrow}}^{1}$${\mathit{S}}_{0}$ was determined from the duration of the dark periods: \ensuremath{\tau}${(}^{3}$${\mathit{P}}_{0}$)=0.14(2) s. This value is compared to calculations based on perturbation theory. Prospects for an optical frequency standard using the narrow 5${\mathit{s}}^{2}$ $^{1}$${\mathit{S}}_{0}$\ensuremath{\rightarrow}5s5p $^{3}$${\mathit{P}}_{0}$ resonance at 236.5 nm of a single laser-cooled indium ion are discussed.

European Quantum Electronics Conference (EQEC)•Aug 24, 2005•2 citations
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 \ensuremathα\ensuremath{\alpha}\ensuremathα-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 224Ra7s21S0\ensuremath→7s7p1P1^{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}224Ra7s21S0​\ensuremath→7s7p1P1​ transition frequency: 621043830\ifmmode±\else\textpm\fi60621\phantom{\rule{0.16em}{0ex}}043\phantom{\rule{0.16em}{0ex}}830\ifmmode\pm\else\textpm\fi{}60621043830\ifmmode±\else\textpm\fi60 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 621037830\ifmmode±\else\textpm\fi60621\phantom{\rule{0.16em}{0ex}}037\phantom{\rule{0.16em}{0ex}}830\ifmmode\pm\else\textpm\fi{}60621037830\ifmmode±\else\textpm\fi60 MHz, which disagrees with the most precise measurement, 621038489\ifmmode±\else\textpm\fi15621\phantom{\rule{0.16em}{0ex}}038\phantom{\rule{0.16em}{0ex}}489\ifmmode\pm\else\textpm\fi{}15621038489\ifmmode±\else\textpm\fi15 MHz, which is used for the recommended value in the National Institute of Standards and Technology Atomic Spectra Database.
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.
Measurement of 7p 2P1/2o7p\ ^2P_{1/2}^o7p 2P1/2o​ branching fractions with laser-cooled 226Ra+^{226}\mathrm{Ra}^+226Ra+
The unstable radium nucleus is appealing for probing new physics due to its high mass, octupole deformation and energy level structure. Ion traps, with long hold times and low particle numbers, are excellent for work with radioactive species, such as radium and radium-based molecular ions, where low activity, and hence low total numbers, is desirable. We address the challenges associated with the lack of stable isotopes in a table-top experiment with a low-activity (∼10μCi\sim 10 \mu\mathrm{Ci}∼10μCi) source where we laser-cool radium ions to form radium Wigner crystals. With a laser-cooled radium ion we measured the 7p2P1/2o7p ^2P_{1/2}^o7p2P1/2o​ state's branching fractions to the ground state, 7s2S1/27s ^2S_{1/2}7s2S1/2​, and a metastable excited state, 6d2D3/26d ^2D_{3/2}6d2D3/2​, to be p=0.9104(7)p=0.9104(7)p=0.9104(7) and 0.0896(7)0.0896(7)0.0896(7), respectively. With a nearby tellurium reference line we measured the 7s2S1/2→7p2P1/2o7s ^2S_{1/2} \rightarrow 7p ^2P_{1/2}^o7s2S1/2​→7p2P1/2o​ transition frequency, 640.09663(6) THz.
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.
The unstable radium nucleus is appealing for probing new physics due to its high mass, octupole deformation, and energy level structure. Ion traps, with long hold times and low particle numbers, are excellent for work with radioactive species, such as radium and radium-based molecular ions, where low activity, and hence low total numbers, is desirable. We address the challenges associated with the lack of stable isotopes in a tabletop experiment with a low-activity (∼10 μCi) source where we laser-cool trapped radium ions. With a laser-cooled radium ion we measured the 7p^{2}P_{1/2}^{o} state's branching fractions to the ground state, 7s^{2}S_{1/2}, and a metastable excited state, 6d^{2}D_{3/2}, to be p=0.9104(7) and 0.0896(7), respectively. With a nearby tellurium reference line we measured the 7s^{2}S_{1/2}→7p^{2}P_{1/2}^{o} transition frequency, 640.096 63(6) THz.
We performed laser spectroscopy of In+{\mathrm{In}}^{+}In+ ions stored in a radio-frequency trap. The 5s2{\mathit{s}}^{2}s2 1^{1}1S0{\mathit{S}}_{0}S0​\ensuremath{\rightarrow}5s5p 3^{3}3P1{\mathit{P}}_{1}P1​ transition at 230.6 nm was excited and its hyperfine splitting and isotope shift have been measured. The lifetime of the 3^{3}3P1{\mathit{P}}_{1}P1​ state was measured using intensity modulated laser excitation: \ensuremath{\tau}(3{(}^{3}(3P1{\mathit{P}}_{1}P1​)=0.44(4) \ensuremath{\mu}s. A single indium ion was laser cooled using this intercombination line and dark periods in the fluorescence were observed when the metastable 3^{3}3P0{\mathit{P}}_{0}P0​ state was populated by a magnetic dipole decay from 3^{3}3P1{\mathit{P}}_{1}P1​. The radiative lifetime of the forbidden transition 3^{3}3P0{\mathit{P}}_{0}P0​${\ensuremath{\rightarrow}}^{1}$S0{\mathit{S}}_{0}S0​ was determined from the duration of the dark periods: \ensuremath{\tau}(3{(}^{3}(3P0{\mathit{P}}_{0}P0​)=0.14(2) s. This value is compared to calculations based on perturbation theory. Prospects for an optical frequency standard using the narrow 5s2{\mathit{s}}^{2}s2 1^{1}1S0{\mathit{S}}_{0}S0​\ensuremath{\rightarrow}5s5p 3^{3}3P0{\mathit{P}}_{0}P0​ resonance at 236.5 nm of a single laser-cooled indium ion are discussed.
We performed laser spectroscopy of In+{\mathrm{In}}^{+}In+ ions stored in a radio-frequency trap. The 5s2{\mathit{s}}^{2}s2 1^{1}1S0{\mathit{S}}_{0}S0​\ensuremath{\rightarrow}5s5p 3^{3}3P1{\mathit{P}}_{1}P1​ transition at 230.6 nm was excited and its hyperfine splitting and isotope shift have been measured. The lifetime of the 3^{3}3P1{\mathit{P}}_{1}P1​ state was measured using intensity modulated laser excitation: \ensuremath{\tau}(3{(}^{3}(3P1{\mathit{P}}_{1}P1​)=0.44(4) \ensuremath{\mu}s. A single indium ion was laser cooled using this intercombination line and dark periods in the fluorescence were observed when the metastable 3^{3}3P0{\mathit{P}}_{0}P0​ state was populated by a magnetic dipole decay from 3^{3}3P1{\mathit{P}}_{1}P1​. The radiative lifetime of the forbidden transition 3^{3}3P0{\mathit{P}}_{0}P0​${\ensuremath{\rightarrow}}^{1}$S0{\mathit{S}}_{0}S0​ was determined from the duration of the dark periods: \ensuremath{\tau}(3{(}^{3}(3P0{\mathit{P}}_{0}P0​)=0.14(2) s. This value is compared to calculations based on perturbation theory. Prospects for an optical frequency standard using the narrow 5s2{\mathit{s}}^{2}s2 1^{1}1S0{\mathit{S}}_{0}S0​\ensuremath{\rightarrow}5s5p 3^{3}3P0{\mathit{P}}_{0}P0​ resonance at 236.5 nm of a single laser-cooled indium ion are discussed.