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

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE

Frequency measurement of the40Ca+clock transition using a LD-based clock laser and UTC(NICT)

K. Matsubara, Y. Li, Shigeo Nagano, Hiroyuki Ito, Masatoshi Kajita, Reiko Kojima, K. Hayasaka, Mizuhiko Hosokawa, Yuko Hanado

Published Aug 20, 2009• 0 citations
Publisher

Abstract

We developed an optical frequency standard with the 4 2S1/2-3 2D5/2 electric quadrupole transition of 40Ca+ ions. Its absolute transition frequency is 411 042 129 776 390(±7) Hz. The accuracy is limited by the electric quadrupole shift and the ambient magnetic field fluctuation. To determine the absolute transition frequency with a better accuracy, we have observed two pairs of the symmetrically-splitting Zeeman components and measured the transition frequency corrected for the electric quadrupole shift. In addition, we are developing a magnetic-shielded ion-trap chamber to suppress the transition-line broadening caused by the magnetic field fluctuation.

DOI
10.1117/12.825905

Related papers

Absolute frequency measurement of the 40Ca+ clock transition using a LD-based clock laser and UTC(NICT)

Kensuke Matsubara, Ying Li, Shigeo Nagano +6 more

We developed an optical frequency standard using40Ca+with the 42S1/2-32D5/2electric quadrupole transition. Its absolute transition frequency is 411 042 129 776 390(7) Hz. The uncertainty is limited by the electric quadrupole shift and ambient magnetic field fluctuation. To determine the absolute transition frequency with a better uncertainty, we have observed two pairs of the symmetrically-splitting Zeeman components and measured the transition frequency which is corrected for the electric quadrupole shift. It will be used to determine the absolute transition frequency with respect to the SI base units of time and length. In addition, we are developing a magnetic-shielded ion-trap chamber to reduce the transition-line broadening caused by the magnetic field fluctuation.

Joint Conference of the European Frequency and Time Forum and IEEE International Frequency Control Symposium (EFTF/IFCS)•Apr 1, 2009•2 citations

Improved measurement of the40Ca+clock transition frequency towards an uncertainty of 10−15level

Kensuke Matsubara, Kazuhiro Hayasaka, Ying Li +7 more

We report improved frequency measurement of a single40Ca+optical clock towards the 10-15uncertainty level. In contrast with our previous measurement, in which the accuracy was limited by the magnetic field fluctuation, the use of a magnetic shield significantly reduced the observed linewidth of its2S1/2-2D5/2clock transition. From frequency comparison between the40Ca+clock and an87Sr lattice clock, an Allan deviation of 7 × 10-16at an averaging time of one thousand seconds was measured. We now measure the absolute frequency of the40Ca+clock transition with respect to the SI definition of the second.

URSI General Assembly and Scientific Symposium•Aug 1, 2011•0 citations

Quadrupole Transition Spectrum Measurement of Single Ca+ Ions Toward Optical Frequency Standards

Kensuke Matsubara, Ying Li, Kyoya Fukuda +6 more

The National Institute of Information and Communications Technology in Japan is proceeding with development of an optical frequency standard using an electric quadrupole transition of Ca+ ions in a small radio-frequency trap. The single, trapped 40Ca+ ions are laser cooled to a temperature of <10 mK using extended-cavity diode lasers at 397 nm and 866 nm. In order to measure the electric quadrupole transition, the linewidth of the clock laser diode at 729 nm is reduced to ~66 Hz using an ultra-low-expansion (ULE) cavity. We observed the electric quadrupole transition with a linewidth of ~600 kHz, together with the ionic motional sidebands. We are also developing optical frequency combs without photonic fibers broadening the spectrum. The experimental is now improved in order to observe the narrower linewidth of the quadrupole transition.

•Dec 9, 2006•0 citations

40Ca+ optical frequency standards with high accuracy

Guan Hua, Yao Huang, Chengbin Li +1 more

With the development of the technologies in the lasers and the manipulation of cold atoms, the high precision optical frequency standards have been extensively studied and built in recent years. These high precision frequency standards may play an important role in establishing the new time reference, promoting the researches in the fundamental fields, fulfilling the national strategic needs, etc. In this paper, the research progress of high accuracy 40Ca+ optical frequency standard in Wuhan Institute of Physics and Mathematics (WIPM) of Chinese Academy of Sciences is presented. A new ULE super cavity is adopted for stabilizing the frequency of 729 nm clock laser, and the stability of the laser is improved now to 2×10-15 in a duration of 1-100 s. By controlling the external fields and other environmental influences, especially suppressing the micromotion effects of the trapped ion, the uncertainty of the optical frequency standard based on a single 40Ca+ is reduced to 5.5×10-17. The stability of 5×10-17 in a duration of 20000 s is achieved via the comparison between two 40Ca+ optical frequency standards. Several precision measurement experiments are performed, based on the high precision 40Ca+ optical frequency standard. The absolute value of the clock transition frequency of the 40Ca+ optical frequency standard is measured second time, using an optical comb referenced to a hydrogen maser which is calibrated via GPS referenced to UTC (NIM)) using the precise point positioning data-processing technique. The frequency offset of UTC (NIM) relative to the SI second can be evaluated through BIPM circular-T reports, and the newly measured value of m 4s 2S1/2-3m d 2D5/2 transition is adopted by CCTF-20, thus updating the recommended value of 40Ca+ optical clock transition. Besides the absolute frequency measurement, the magic wavelengths of 40Ca+ optical clock transition are measured precisely, and this work is a milestone for establishing all-optical trapped-ion clocks. The lifetime of the m 3 d 2D3/2 and m 3 d 2D5/2 state in 40Ca+ are precisely measured, too. The work mentioned above contributes to the researches of the precision measurements based on cold atomic systems.

Acta Physica Sinica•Jan 1, 2018•4 citations

Optical frequency standard based on a single 40Ca+

Kelin Gao

Research on the development of the optical frequency standard based on trapped and cold 40 Ca + with the 4s 2 S 1/2 -3d 2 D 5/2 clock transition at 729 nm is reported. A single calcium ion was trapped and laser cooled in the Paul trap and stay in trap for more than 15 days. The linewidth of a 729 nm laser was reduced to less than 10 Hz by locking to a cavity for longer than 50 hours uninterruptedly. The overall systematic uncertainty of the clock transition has been characterized to be better than 6.5×10 −16 . The absolute frequency of the clock transition was measured at 10 −15 level using an optical frequency comb referenced to a Hydrogen maser, which was calibrated to the SI second through the global positioning system (GPS). The frequency value was 411042129776393.0(1.6) Hz after the correction of the systematic shifts.

Chinese Science Bulletin•Mar 1, 2013•9 citations

High-resolution spectroscopy of the88Sr+single ion optical frequency standard

P. Dubé, Alan A. Madej, J. E. Bernard +1 more

The present decade has seen great advances in optical frequency standards following the development of femtosecond laser frequency combs. With this technology, combined with a stable and narrow probe laser source (50-100 Hz linewidth), we made a systematic study of the 5s 2S1/2-4d 2D5/2 (S-D) transition frequency of the 88Sr+ ion as a function of the quantization axis in the trap. This study revealed the presence of systematic shifts caused by residual micromotion in our rf Paul trap and led to an evaluation of those shifts. Also, a method was developed based on the measurement of the Zeeman spectrum of the clock transition to cancel the electric quadrupole shift caused by patch potentials on the trap electrodes. From these results, we also determined the absolute frequency of the S-D clock transition frequency at 674 nm with a fractional frequency uncertainty of 3.4 × 10-14. We have since made improvements to our probe laser system and have observed 5 Hz Fourier transform limited linewidths on a Zeeman component of the S-D transition of the 88Sr+ ion. To observe such a narrow transition it is essential to have a known and well behaved drift of the laser frequency during the few minutes it takes to measure the ion resonance using the quantum jump signal. Our approach to minimize the drift rate and its sensitivity to temperature fluctuations has been to stabilize the cavity at the temperature where its coefficient of thermal expansion is zero. We will present an overview of our recent progress made on the frequency standard based on the laser-cooled and trapped single ion of 88Sr+.

Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE•Aug 29, 2007•8 citations
We developed an optical frequency standard with the 4 2S1/2-3 2D5/2 electric quadrupole transition of 40Ca+ ions. Its absolute transition frequency is 411 042 129 776 390(±7) Hz. The accuracy is limited by the electric quadrupole shift and the ambient magnetic field fluctuation. To determine the absolute transition frequency with a better accuracy, we have observed two pairs of the symmetrically-splitting Zeeman components and measured the transition frequency corrected for the electric quadrupole shift. In addition, we are developing a magnetic-shielded ion-trap chamber to suppress the transition-line broadening caused by the magnetic field fluctuation.
We developed an optical frequency standard using40Ca+with the 42S1/2-32D5/2electric quadrupole transition. Its absolute transition frequency is 411 042 129 776 390(7) Hz. The uncertainty is limited by the electric quadrupole shift and ambient magnetic field fluctuation. To determine the absolute transition frequency with a better uncertainty, we have observed two pairs of the symmetrically-splitting Zeeman components and measured the transition frequency which is corrected for the electric quadrupole shift. It will be used to determine the absolute transition frequency with respect to the SI base units of time and length. In addition, we are developing a magnetic-shielded ion-trap chamber to reduce the transition-line broadening caused by the magnetic field fluctuation.
We report improved frequency measurement of a single40Ca+optical clock towards the 10-15uncertainty level. In contrast with our previous measurement, in which the accuracy was limited by the magnetic field fluctuation, the use of a magnetic shield significantly reduced the observed linewidth of its2S1/2-2D5/2clock transition. From frequency comparison between the40Ca+clock and an87Sr lattice clock, an Allan deviation of 7 × 10-16at an averaging time of one thousand seconds was measured. We now measure the absolute frequency of the40Ca+clock transition with respect to the SI definition of the second.
The National Institute of Information and Communications Technology in Japan is proceeding with development of an optical frequency standard using an electric quadrupole transition of Ca+ ions in a small radio-frequency trap. The single, trapped 40Ca+ ions are laser cooled to a temperature of <10 mK using extended-cavity diode lasers at 397 nm and 866 nm. In order to measure the electric quadrupole transition, the linewidth of the clock laser diode at 729 nm is reduced to ~66 Hz using an ultra-low-expansion (ULE) cavity. We observed the electric quadrupole transition with a linewidth of ~600 kHz, together with the ionic motional sidebands. We are also developing optical frequency combs without photonic fibers broadening the spectrum. The experimental is now improved in order to observe the narrower linewidth of the quadrupole transition.
With the development of the technologies in the lasers and the manipulation of cold atoms, the high precision optical frequency standards have been extensively studied and built in recent years. These high precision frequency standards may play an important role in establishing the new time reference, promoting the researches in the fundamental fields, fulfilling the national strategic needs, etc. In this paper, the research progress of high accuracy 40Ca+ optical frequency standard in Wuhan Institute of Physics and Mathematics (WIPM) of Chinese Academy of Sciences is presented. A new ULE super cavity is adopted for stabilizing the frequency of 729 nm clock laser, and the stability of the laser is improved now to 2×10-15 in a duration of 1-100 s. By controlling the external fields and other environmental influences, especially suppressing the micromotion effects of the trapped ion, the uncertainty of the optical frequency standard based on a single 40Ca+ is reduced to 5.5×10-17. The stability of 5×10-17 in a duration of 20000 s is achieved via the comparison between two 40Ca+ optical frequency standards. Several precision measurement experiments are performed, based on the high precision 40Ca+ optical frequency standard. The absolute value of the clock transition frequency of the 40Ca+ optical frequency standard is measured second time, using an optical comb referenced to a hydrogen maser which is calibrated via GPS referenced to UTC (NIM)) using the precise point positioning data-processing technique. The frequency offset of UTC (NIM) relative to the SI second can be evaluated through BIPM circular-T reports, and the newly measured value of m 4s 2S1/2-3m d 2D5/2 transition is adopted by CCTF-20, thus updating the recommended value of 40Ca+ optical clock transition. Besides the absolute frequency measurement, the magic wavelengths of 40Ca+ optical clock transition are measured precisely, and this work is a milestone for establishing all-optical trapped-ion clocks. The lifetime of the m 3 d 2D3/2 and m 3 d 2D5/2 state in 40Ca+ are precisely measured, too. The work mentioned above contributes to the researches of the precision measurements based on cold atomic systems.
Research on the development of the optical frequency standard based on trapped and cold 40 Ca + with the 4s 2 S 1/2 -3d 2 D 5/2 clock transition at 729 nm is reported. A single calcium ion was trapped and laser cooled in the Paul trap and stay in trap for more than 15 days. The linewidth of a 729 nm laser was reduced to less than 10 Hz by locking to a cavity for longer than 50 hours uninterruptedly. The overall systematic uncertainty of the clock transition has been characterized to be better than 6.5×10 −16 . The absolute frequency of the clock transition was measured at 10 −15 level using an optical frequency comb referenced to a Hydrogen maser, which was calibrated to the SI second through the global positioning system (GPS). The frequency value was 411042129776393.0(1.6) Hz after the correction of the systematic shifts.
The present decade has seen great advances in optical frequency standards following the development of femtosecond laser frequency combs. With this technology, combined with a stable and narrow probe laser source (50-100 Hz linewidth), we made a systematic study of the 5s 2S1/2-4d 2D5/2 (S-D) transition frequency of the 88Sr+ ion as a function of the quantization axis in the trap. This study revealed the presence of systematic shifts caused by residual micromotion in our rf Paul trap and led to an evaluation of those shifts. Also, a method was developed based on the measurement of the Zeeman spectrum of the clock transition to cancel the electric quadrupole shift caused by patch potentials on the trap electrodes. From these results, we also determined the absolute frequency of the S-D clock transition frequency at 674 nm with a fractional frequency uncertainty of 3.4 × 10-14. We have since made improvements to our probe laser system and have observed 5 Hz Fourier transform limited linewidths on a Zeeman component of the S-D transition of the 88Sr+ ion. To observe such a narrow transition it is essential to have a known and well behaved drift of the laser frequency during the few minutes it takes to measure the ion resonance using the quantum jump signal. Our approach to minimize the drift rate and its sensitivity to temperature fluctuations has been to stabilize the cavity at the temperature where its coefficient of thermal expansion is zero. We will present an overview of our recent progress made on the frequency standard based on the laser-cooled and trapped single ion of 88Sr+.