We report the 87Sr optical lattice clock developed at the National Time Service Center. We achieved a closed-loop operation of the optical lattice clock based on 87Sr atoms. The linewidth of the spin-polarized clock p...We report the 87Sr optical lattice clock developed at the National Time Service Center. We achieved a closed-loop operation of the optical lattice clock based on 87Sr atoms. The linewidth of the spin-polarized clock peak is 3.9 Hz with a clock laser pulse length of 300 ms, which corresponds to a Fourier-limited linewidth of 3 Hz. The fitting of the in-loop error signal data shows that the instability is approximately 5 × 10 15τ-1/2, affected primarily by the white noise. The fractional frequency difference averages down to 5.7 × 10 ^-17 for an averaging time of 3000 s.展开更多
We report on studies of an optical lattice for a strontium clock performed at the National Time Service Center. Follow-ing tw o-stage laser cooling and trapping,88 Sr cold atoms w ith population of 105 and a longitudi...We report on studies of an optical lattice for a strontium clock performed at the National Time Service Center. Follow-ing tw o-stage laser cooling and trapping,88 Sr cold atoms w ith population of 105 and a longitudinal temperature of 8. 4 μK are loaded into a one-dimensional optical lattice. Spectroscopic analysis of the1S0-3P0 transition gives a linew idth of 180 Hz measured using magnetic field-induction,w hich mixes the3P1 state w ith the3P0 state. Rabi oscillations are observed. Because of the inhomogeneous excitation among the atoms,the Rabi π-pulse excitation at 5 ms show s a near 65% excitation of atoms. The transverse velocity distribution of the atomic beam and the absolute frequencies of the four inter-combination transitions of the isotopes w as measured precisely using velocity-selective fluorescence spectroscopy. By optical injection of tw o cascade external-cavity diode lasers,a single comb line at 689 nm from an optical femtosecond laser comb is filtered and amplified w ith a 37-d B side-mode suppression and a linew idth of less than 240 Hz. We describe recent w ork on a space optical clock concerning the physical vacuum system,thermal analysis,and a permanent-magnet Zeeman slow er for a space strontium optical clock. The first six mode frequencies are obtained and the corresponding oscillation modes are described in detail. We also simulate and analyze thermal profiles for both the physical and optical units installed in the cooling system. When the injected cooling w ater has a temperature of 21℃ or28℃,the units meet operational requirements for temperatures in a space environment. Using a series of permanent magnets,a Zeeman slow er is built that can w ithstand space launching and operating conditions for the space optical clock.展开更多
We report a transportable one-dimensional optical lattice clock based on 87Sr at the National Time Service Center.The transportable apparatus consists of a compact vacuum system and compact optical subsystems.The vacu...We report a transportable one-dimensional optical lattice clock based on 87Sr at the National Time Service Center.The transportable apparatus consists of a compact vacuum system and compact optical subsystems.The vacuum system with a size of 90 cm×20 cm×42 cm and the beam distributors are assembled on a double-layer optical breadboard.The modularized optical subsystems are integrated on independent optical breadboards.By using a 230 ms clock laser pulse,spin-polarized spectroscopy with a linewidth of 4.8 Hz is obtained which is close to the 3.9 Hz Fourier-limit linewidth.The time interleaved self-comparison frequency instability is determined to be 6.3 × 10^-17 at an averaging time of 2000 s.展开更多
A miniaturized atomic emission spectrometer was constructed,using a tungsten coil as the electrothermal excitation source and a handheld CCD spectrometer as the detection device.The limits of detection for calcium and...A miniaturized atomic emission spectrometer was constructed,using a tungsten coil as the electrothermal excitation source and a handheld CCD spectrometer as the detection device.The limits of detection for calcium and strontium with this new instrument were 0.03 and 0.02 mg/L,respectively, while the upper linear dynamic range for calcium andstrontium were 1000 and 400 mg/L,respectively.The proposed method was applied to simultaneous determination of calcium and strontium in synthesized brine samples,and the analytical results were in good agreement with those by ICP-AES.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11474282 and 61775220)the Key Research Project of Frontier Science of the Chinese Academy of Sciences(Grant No.QYZDB-SSW-JSC004)the Strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB21030700)
文摘We report the 87Sr optical lattice clock developed at the National Time Service Center. We achieved a closed-loop operation of the optical lattice clock based on 87Sr atoms. The linewidth of the spin-polarized clock peak is 3.9 Hz with a clock laser pulse length of 300 ms, which corresponds to a Fourier-limited linewidth of 3 Hz. The fitting of the in-loop error signal data shows that the instability is approximately 5 × 10 15τ-1/2, affected primarily by the white noise. The fractional frequency difference averages down to 5.7 × 10 ^-17 for an averaging time of 3000 s.
文摘We report on studies of an optical lattice for a strontium clock performed at the National Time Service Center. Follow-ing tw o-stage laser cooling and trapping,88 Sr cold atoms w ith population of 105 and a longitudinal temperature of 8. 4 μK are loaded into a one-dimensional optical lattice. Spectroscopic analysis of the1S0-3P0 transition gives a linew idth of 180 Hz measured using magnetic field-induction,w hich mixes the3P1 state w ith the3P0 state. Rabi oscillations are observed. Because of the inhomogeneous excitation among the atoms,the Rabi π-pulse excitation at 5 ms show s a near 65% excitation of atoms. The transverse velocity distribution of the atomic beam and the absolute frequencies of the four inter-combination transitions of the isotopes w as measured precisely using velocity-selective fluorescence spectroscopy. By optical injection of tw o cascade external-cavity diode lasers,a single comb line at 689 nm from an optical femtosecond laser comb is filtered and amplified w ith a 37-d B side-mode suppression and a linew idth of less than 240 Hz. We describe recent w ork on a space optical clock concerning the physical vacuum system,thermal analysis,and a permanent-magnet Zeeman slow er for a space strontium optical clock. The first six mode frequencies are obtained and the corresponding oscillation modes are described in detail. We also simulate and analyze thermal profiles for both the physical and optical units installed in the cooling system. When the injected cooling w ater has a temperature of 21℃ or28℃,the units meet operational requirements for temperatures in a space environment. Using a series of permanent magnets,a Zeeman slow er is built that can w ithstand space launching and operating conditions for the space optical clock.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61775220 and 11803042)the Key Research Project of Frontier Science of the Chinese Academy of Sciences(Grant No.QYZDB-SSW-JSC004)the strategic Priority Research Program of the Chinese Academy of Sciences(Grant No.XDB21030100).
文摘We report a transportable one-dimensional optical lattice clock based on 87Sr at the National Time Service Center.The transportable apparatus consists of a compact vacuum system and compact optical subsystems.The vacuum system with a size of 90 cm×20 cm×42 cm and the beam distributors are assembled on a double-layer optical breadboard.The modularized optical subsystems are integrated on independent optical breadboards.By using a 230 ms clock laser pulse,spin-polarized spectroscopy with a linewidth of 4.8 Hz is obtained which is close to the 3.9 Hz Fourier-limit linewidth.The time interleaved self-comparison frequency instability is determined to be 6.3 × 10^-17 at an averaging time of 2000 s.
文摘A miniaturized atomic emission spectrometer was constructed,using a tungsten coil as the electrothermal excitation source and a handheld CCD spectrometer as the detection device.The limits of detection for calcium and strontium with this new instrument were 0.03 and 0.02 mg/L,respectively, while the upper linear dynamic range for calcium andstrontium were 1000 and 400 mg/L,respectively.The proposed method was applied to simultaneous determination of calcium and strontium in synthesized brine samples,and the analytical results were in good agreement with those by ICP-AES.
