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Conference on Lasers and Electro-Optics

Indium single-ion optical frequency standard

Th. Becker, Alexander Yu. Nevsky, Mikhail N Skvortsov, Ch. Schwedes, M. Eichenseer, Joachim von Zanthier, E. Peik, HERBERT WALTHER

Published Aug 29, 2005• 2 citations
Publisher

Abstract

Summary form only given. Laser-cooled ions in radiofrequency traps are the atomic systems that allow the highest resolution (ratio of frequency to linewidth) in optical or microwave spectroscopy. They can serve as references in highly stable frequency standards and also enable precise tests of fundamental physics. We present recent results on our In/sup +/ optical frequency standard, based on the 5s/sup 2/ /sup 1/S/sub 0//spl rarr/5s5p /sup 3/P/sub 0/ transition at 236.5 nm wavelength. This transition has a natural linewidth of only 0.82 Hz and is highly immune to systematic frequency shifts.

DOI
10.1109/iqec.2000.907790

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Indium single ion optical frequency standard

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A single laser cooled ion in a radiofrequency trap can serve as the basis for a highly stable optical frequency standard. We present recent results of our work on single indium ions, using the /sup 1/S/sub 0/ to /sup 3/P/sub 0/ transition at 236.5 nm wave-length as the clock transition. This resonance has a linewidth of only 0.82 Hz where systematic shifts should be controllable on the mHz level. A single In/sup +/ ion is stored in a miniature Paul-Straubel trap and laser cooled to a temperature of about 100 /spl mu/K. The clock transition is excited using a frequency quadrupled Nd:YAG laser. A fractional resolution of 1.3/spl middot/10/sup -13/ has been achieved so far (linewidth of 170 Hz at 1267 THz). The absolute frequency of the clock transition clock transition has been measured with an uncertainty of 2/spl middot/10/sup -13/ using a frequency chain and a methane-stabilized HeNe laser as a reference, that was calibrated with a cesium clock.

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Towards an indium single-ion optical clock

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We are investigating the 5s/sup 21/S/sub 0//spl rarr/5s5p/sup 3/P/sub 0/ transition of a single trapped laser-cooled /sup 115/In/sup +/ ion as a possible optical frequency standard. This line with a natural linewidth of only 1.1 Hz, corresponding to a Q factor of 1.2/spl middot/10/sup 15/, is highly immune to systematic frequency shifts due to external perturbations. For sideband laser cooling and fluorescence detection of the indium ion the 5s/sup 21/S/sub 0//spl rarr/5s5p/sup 3/P/sub 1/ transition at 230.6 nm is excited. Temperatures below 100 /spl mu/K and a mean vibrational quantum number<1 of the ion in the trap have been reached. For the clock transition a resolution of 3/spl middot/10/sup -13/ (linewidth 350 Hz) has been obtained so far, limited by the laser linewidth. The absolute frequency of the /sup 1/S/sub 0//spl rarr//sup 3/P/sub 0/ transition was measured by making a link to known reference frequencies of molecular iodine and methane using a frequency chain.

Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS)•Jan 22, 2003•1 citation

Indium single-ion optical frequency standard

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Single laser-cooled ions in radiofrequency traps can serve as the basis for highly stable optical frequency standards. Here we present recent results on In+, using the 1S0 yields 3P0 line at 236.5 nm wavelength as the clock transition. This resonance has a natural linewidth of only 0.82 Hz and systematic shifts should be controllable at the mHz level. A single indium ion is stored in a miniature Paul- Straubel trap and laser cooled to a temperature of about 100 (mu) K. The clock transition is excited using a frequency quadrupled 946 nm Nd:YAG laser. A fractional resolution of 1.3 (DOT) 10-13 has been achieved so far (linewidth of 170 Hz at 1267 THz). The absolute optical frequency of the clock transition has been measured with an uncertainty being less than 3 (DOT) 10-13 using a frequency chain and a methane-stabilized HeNe laser that was calibrated with a cesium clock.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•May 3, 2001•0 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.

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Summary form only given. A single laser-cooled indium ion, stored in a radio-frequency trap, is expected to be one of the most promising candidates for the creation of a new generation of optical frequency standards with an anticipated accuracy of up to 10/sup -18/. On the way to achieving such a high level of accuracy, one of the main limitations is the short-term frequency instability of the laser system, used to excite the narrow /sup 1/S/sub 0/-/sup 3/P/sub 0/ In/sup +/ clock transition. Since the signal from the single ion is small, the laser system should posses extremely high frequency stability (on the level of /spl Delta/v/v=10/sup -14//spl divide/10/sup -15/) for averaging times of about one second in order to reduce statistical uncertainties and to minimize the time of experiment. In this paper, we report our recent results on the improvement of the short-term frequency stability of the laser system.

Quantum Electronics and Laser Science Conference•Nov 13, 2002•0 citations

High-resolution spectroscopy of a single In+ ion: Progress towards an optical frequency standard

Th. Becker, Joachim von Zanthier, Alexander Yu. Nevsky +4 more

The ${5s}^{2}{}^{1}{S}_{0}\ensuremath{\rightarrow}5s5p{}^{3}{P}_{0}$ transition of a single laser-cooled ${}^{115}{\mathrm{In}}^{+}$ ion in a miniature radiofrequency trap is investigated as a possible optical frequency standard. This line at a frequency of 1267 THz (wavelength 236.5 nm) is highly immune to frequency shifts due to external perturbations so that the expected systematic uncertainties can be reduced to the millihertz level. Experimentally, we obtained a fractional resolution $\ensuremath{\Delta}\ensuremath{\nu}/\ensuremath{\nu}=1.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}$ (linewidth 170 Hz), limited by the frequency instability of the laser used for excitation. The g factor and the lifetime of the metastable ${}^{3}{P}_{0}$ level were measured as ${g(}^{3}{P}_{0})=\ensuremath{-}9.87(5)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ and $\ensuremath{\tau}{(}^{3}{P}_{0})=0.195(8) \mathrm{s}.$ Both values are in good agreement with perturbative calculations, based on hyperfine mixing between the ${}^{1}P$ and ${}^{3}P$ levels.

Physical Review A•Apr 16, 2001•106 citations
Summary form only given. Laser-cooled ions in radiofrequency traps are the atomic systems that allow the highest resolution (ratio of frequency to linewidth) in optical or microwave spectroscopy. They can serve as references in highly stable frequency standards and also enable precise tests of fundamental physics. We present recent results on our In/sup +/ optical frequency standard, based on the 5s/sup 2/ /sup 1/S/sub 0//spl rarr/5s5p /sup 3/P/sub 0/ transition at 236.5 nm wavelength. This transition has a natural linewidth of only 0.82 Hz and is highly immune to systematic frequency shifts.
A single laser cooled ion in a radiofrequency trap can serve as the basis for a highly stable optical frequency standard. We present recent results of our work on single indium ions, using the /sup 1/S/sub 0/ to /sup 3/P/sub 0/ transition at 236.5 nm wave-length as the clock transition. This resonance has a linewidth of only 0.82 Hz where systematic shifts should be controllable on the mHz level. A single In/sup +/ ion is stored in a miniature Paul-Straubel trap and laser cooled to a temperature of about 100 /spl mu/K. The clock transition is excited using a frequency quadrupled Nd:YAG laser. A fractional resolution of 1.3/spl middot/10/sup -13/ has been achieved so far (linewidth of 170 Hz at 1267 THz). The absolute frequency of the clock transition clock transition has been measured with an uncertainty of 2/spl middot/10/sup -13/ using a frequency chain and a methane-stabilized HeNe laser as a reference, that was calibrated with a cesium clock.
We are investigating the 5s/sup 21/S/sub 0//spl rarr/5s5p/sup 3/P/sub 0/ transition of a single trapped laser-cooled /sup 115/In/sup +/ ion as a possible optical frequency standard. This line with a natural linewidth of only 1.1 Hz, corresponding to a Q factor of 1.2/spl middot/10/sup 15/, is highly immune to systematic frequency shifts due to external perturbations. For sideband laser cooling and fluorescence detection of the indium ion the 5s/sup 21/S/sub 0//spl rarr/5s5p/sup 3/P/sub 1/ transition at 230.6 nm is excited. Temperatures below 100 /spl mu/K and a mean vibrational quantum number<1 of the ion in the trap have been reached. For the clock transition a resolution of 3/spl middot/10/sup -13/ (linewidth 350 Hz) has been obtained so far, limited by the laser linewidth. The absolute frequency of the /sup 1/S/sub 0//spl rarr//sup 3/P/sub 0/ transition was measured by making a link to known reference frequencies of molecular iodine and methane using a frequency chain.
Single laser-cooled ions in radiofrequency traps can serve as the basis for highly stable optical frequency standards. Here we present recent results on In+, using the 1S0 yields 3P0 line at 236.5 nm wavelength as the clock transition. This resonance has a natural linewidth of only 0.82 Hz and systematic shifts should be controllable at the mHz level. A single indium ion is stored in a miniature Paul- Straubel trap and laser cooled to a temperature of about 100 (mu) K. The clock transition is excited using a frequency quadrupled 946 nm Nd:YAG laser. A fractional resolution of 1.3 (DOT) 10-13 has been achieved so far (linewidth of 170 Hz at 1267 THz). The absolute optical frequency of the clock transition has been measured with an uncertainty being less than 3 (DOT) 10-13 using a frequency chain and a methane-stabilized HeNe laser that was calibrated with a cesium clock.
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.
Summary form only given. A single laser-cooled indium ion, stored in a radio-frequency trap, is expected to be one of the most promising candidates for the creation of a new generation of optical frequency standards with an anticipated accuracy of up to 10/sup -18/. On the way to achieving such a high level of accuracy, one of the main limitations is the short-term frequency instability of the laser system, used to excite the narrow /sup 1/S/sub 0/-/sup 3/P/sub 0/ In/sup +/ clock transition. Since the signal from the single ion is small, the laser system should posses extremely high frequency stability (on the level of /spl Delta/v/v=10/sup -14//spl divide/10/sup -15/) for averaging times of about one second in order to reduce statistical uncertainties and to minimize the time of experiment. In this paper, we report our recent results on the improvement of the short-term frequency stability of the laser system.
The ${5s}^{2}{}^{1}{S}_{0}\ensuremath{\rightarrow}5s5p{}^{3}{P}_{0}$ transition of a single laser-cooled 115In+{}^{115}{\mathrm{In}}^{+}115In+ ion in a miniature radiofrequency trap is investigated as a possible optical frequency standard. This line at a frequency of 1267 THz (wavelength 236.5 nm) is highly immune to frequency shifts due to external perturbations so that the expected systematic uncertainties can be reduced to the millihertz level. Experimentally, we obtained a fractional resolution $\ensuremath{\Delta}\ensuremath{\nu}/\ensuremath{\nu}=1.3\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}$ (linewidth 170 Hz), limited by the frequency instability of the laser used for excitation. The g factor and the lifetime of the metastable 3P0{}^{3}{P}_{0}3P0​ level were measured as ${g(}^{3}{P}_{0})=\ensuremath{-}9.87(5)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ and $\ensuremath{\tau}{(}^{3}{P}_{0})=0.195(8) \mathrm{s}.$ Both values are in good agreement with perturbative calculations, based on hyperfine mixing between the 1P{}^{1}P1P and 3P{}^{3}P3P levels.