This paper reports an experiment on laser cooling of STRb atoms in pulsed diffuse light, which is the key step towards a compact cold atom clock. It deduces an empirical formula to simulate the pulse cooling process b...This paper reports an experiment on laser cooling of STRb atoms in pulsed diffuse light, which is the key step towards a compact cold atom clock. It deduces an empirical formula to simulate the pulse cooling process based on the loading of cold atoms in cooling time and the loss in the dead time, which is in agreement with the experimental data. The formula gives a reference to select the parameters for the cold atom clock.展开更多
We develop an integrated integrating sphere cold atom clock(ISCAC), which mainly consists of physical package,laser system, microwave source, and electronics.This compact system is more stable and reliable than the pr...We develop an integrated integrating sphere cold atom clock(ISCAC), which mainly consists of physical package,laser system, microwave source, and electronics.This compact system is more stable and reliable than the previous version.The experimental results show that the short term frequency stability of 5.4×10^-13τ-1/2 and 2.9× 10^-15 at 1-day integrating time are achieved.展开更多
The Ramsey fringes with a linewidth of 45 Hz and a signal-to-noise ratio of 120 are demonstrated for a integrating sphere atom clock.The cycle time of the atom clock is reduced to 80 ms with the help of a pulsed cooli...The Ramsey fringes with a linewidth of 45 Hz and a signal-to-noise ratio of 120 are demonstrated for a integrating sphere atom clock.The cycle time of the atom clock is reduced to 80 ms with the help of a pulsed cooling method.This result indicates that the short-term stability of the clock is in the order of 10^(-12).展开更多
This study presents an experiment on diffuse light cooling of atoms in a cylindrical cavity.We focus on the controlling of the shape of the atom cloud by placing the cooling beams in appropriate positions.The Gauss-li...This study presents an experiment on diffuse light cooling of atoms in a cylindrical cavity.We focus on the controlling of the shape of the atom cloud by placing the cooling beams in appropriate positions.The Gauss-like shape of the atomic cloud is demonstrated.The number of cold atoms detected in the cavity is increased,thereby improving the signal-to-noise ratio of the clock signal.展开更多
We propose a simple pumping method to increase the effective population of cold atoms in the clock state and investigate the factors which affect the pumping efficiency in cold atom systems.We report the theory and de...We propose a simple pumping method to increase the effective population of cold atoms in the clock state and investigate the factors which affect the pumping efficiency in cold atom systems.We report the theory and demonstrate the corresponding experiment in an ^(87)Rb integrating sphere cold atom clock.The experimental results show that the population of cold atoms in the Zeeman sublevel|F=2,mF=0>is approximately 1.62 times that of the result using optical pumping alone.This method can also be applied to increase the effective population in any one of the target Zeeman sublevels in other cold atom systems.展开更多
We present an experiment on the measurement of the spatial distribution of cold atoms in a ceramic cell.The atoms are first cooled by diffusing light produced by multiple scattering of laser light at the inner surface...We present an experiment on the measurement of the spatial distribution of cold atoms in a ceramic cell.The atoms are first cooled by diffusing light produced by multiple scattering of laser light at the inner surface of the cell.An inhomogeneous magnetic field is applied after the atoms are cooled by using a pair of anti-Helmholtz coils,and thus the shift of atomic magnetic sub-levels is position-dependent.We move the anti-Helmholtz coils point by point while keeping the probe laser beam resonant with the cold atoms at zero magnetic field.The number of cold atoms at different positions can be extracted by detecting the absorption to the probe beam.The density of the cold atoms in the cell is measured in two dimensions perpendicular and parallel to the tube connecting to the vacuum system,respectively.The results show that at the center of the cell,fewer atoms exist due to the leakage of diffuse light into the hole connecting to the vacuum pump.The method we developed is used to detect cold atoms in a region where imaging is impossible.展开更多
Absolute optical oscillator strength density and double differential cross section spectra of CO below 120 eV are determined by fast electron impact. Some peaks above the first ionization threshold stand out as the mo...Absolute optical oscillator strength density and double differential cross section spectra of CO below 120 eV are determined by fast electron impact. Some peaks above the first ionization threshold stand out as the momentum transfer square K2 increases. The doubly excited Rydberg states converging to C 2∑^＋, D ^2∏, and F ^2∏ states of CO^＋, respectively, are confirmed in our spectra. Another peak at around 32eV is assigned to the transition of （3σ）^-1（2π）^1^1∏←X^1∑^＋.展开更多
We present an experimental measurement of the lifetime of the cold ^87 Rb atoms in an integrating sphere. The atoms are cooled by the diffuse light which is generated by the diffuse reflection of laser beams in the in...We present an experimental measurement of the lifetime of the cold ^87 Rb atoms in an integrating sphere. The atoms are cooled by the diffuse light which is generated by the diffuse reflection of laser beams in the integrating sphere. Our result shows that the lifetime is primarily determined by the free fall of the cold ^87Rb atoms, and its half-life can reach 40 ms, which is suitable for many experiments, especially for a cold atom clock.展开更多
The valence-shell excitations of krypton atom have been investigated by fast electron impact with an angle-resolved electron-energy-loss spectrometer. The generalized oscillator strengths for some higher mixed valence...The valence-shell excitations of krypton atom have been investigated by fast electron impact with an angle-resolved electron-energy-loss spectrometer. The generalized oscillator strengths for some higher mixed valence-shell excitations in 4d, 4f, 5p, 5d, 6s, 6p, 7s ←4p of krypton atom have been determined. Their profiles are discussed, and the generalized oscillator strengths for the electric monopole and quadrupole excitations in 5p ← 4p are compared with the calculations of Amusia et al. （Phys. Rev. A 67 022703 （2003））. The differences between the experimental results and theoretical calculations show that more studies are needed.展开更多
The Dick effect is an important factor limiting the frequency stability of sequentially-operating atomic frequency standards. Here we study the impact of the Dick effect in the integrating sphere cold atom clock （IS...The Dick effect is an important factor limiting the frequency stability of sequentially-operating atomic frequency standards. Here we study the impact of the Dick effect in the integrating sphere cold atom clock （ISCAC）. To reduce the impact of the Dick effect, a 5 MHz local oscillator with ultra-low phase noise is selected and a new microwave synthesizer is built in-house. Consequently, the phase noise of microwave signal is optimized. The contribution of the Dick effect is reduced to 2.5× 10^-13τ-1/2 （3- is the integrating time）. The frequency stability of 4.6 × 10-13τ-1/2 is achieved. The development of this optimization can promote the space applications of the compact ISCA C.展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 10604057 and 10874193)the National High-Tech Programme (Grant No. 2006AA12Z311)the National Basic Research Programme of China (Grant No. 2005CB724506)
文摘This paper reports an experiment on laser cooling of STRb atoms in pulsed diffuse light, which is the key step towards a compact cold atom clock. It deduces an empirical formula to simulate the pulse cooling process based on the loading of cold atoms in cooling time and the loss in the dead time, which is in agreement with the experimental data. The formula gives a reference to select the parameters for the cold atom clock.
基金Project supported by the Youth Innovation Promotion Association of the Chinese Academy of Sciences the National Natural Science Foundation of China(Grant Nos.61875215,61727821,and 11604353)
文摘We develop an integrated integrating sphere cold atom clock(ISCAC), which mainly consists of physical package,laser system, microwave source, and electronics.This compact system is more stable and reliable than the previous version.The experimental results show that the short term frequency stability of 5.4×10^-13τ-1/2 and 2.9× 10^-15 at 1-day integrating time are achieved.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11074262 and 11034008,and the National High-Tech Research and Development Program of China under Grant No 2012AA120702.
文摘The Ramsey fringes with a linewidth of 45 Hz and a signal-to-noise ratio of 120 are demonstrated for a integrating sphere atom clock.The cycle time of the atom clock is reduced to 80 ms with the help of a pulsed cooling method.This result indicates that the short-term stability of the clock is in the order of 10^(-12).
基金Supported by the National Natural Science Foundation of China under Grant Nos 11074262 and 11034008the National High-Tech Research and Development Program under Grant No 2012AA120702.
文摘This study presents an experiment on diffuse light cooling of atoms in a cylindrical cavity.We focus on the controlling of the shape of the atom cloud by placing the cooling beams in appropriate positions.The Gauss-like shape of the atomic cloud is demonstrated.The number of cold atoms detected in the cavity is increased,thereby improving the signal-to-noise ratio of the clock signal.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11074262 and 11034008, and the National High-Tech Research and Development Program under Grant No 2012AA120702.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.61727821,61875215,and 11904408).
文摘We propose a simple pumping method to increase the effective population of cold atoms in the clock state and investigate the factors which affect the pumping efficiency in cold atom systems.We report the theory and demonstrate the corresponding experiment in an ^(87)Rb integrating sphere cold atom clock.The experimental results show that the population of cold atoms in the Zeeman sublevel|F=2,mF=0>is approximately 1.62 times that of the result using optical pumping alone.This method can also be applied to increase the effective population in any one of the target Zeeman sublevels in other cold atom systems.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11074262,10874193 and 11034008.
文摘We present an experiment on the measurement of the spatial distribution of cold atoms in a ceramic cell.The atoms are first cooled by diffusing light produced by multiple scattering of laser light at the inner surface of the cell.An inhomogeneous magnetic field is applied after the atoms are cooled by using a pair of anti-Helmholtz coils,and thus the shift of atomic magnetic sub-levels is position-dependent.We move the anti-Helmholtz coils point by point while keeping the probe laser beam resonant with the cold atoms at zero magnetic field.The number of cold atoms at different positions can be extracted by detecting the absorption to the probe beam.The density of the cold atoms in the cell is measured in two dimensions perpendicular and parallel to the tube connecting to the vacuum system,respectively.The results show that at the center of the cell,fewer atoms exist due to the leakage of diffuse light into the hole connecting to the vacuum pump.The method we developed is used to detect cold atoms in a region where imaging is impossible.
基金Project supported by the National Nature Science Foundation of China （Grant Nos 10474089, 10134010 and 10004010）.
文摘Absolute optical oscillator strength density and double differential cross section spectra of CO below 120 eV are determined by fast electron impact. Some peaks above the first ionization threshold stand out as the momentum transfer square K2 increases. The doubly excited Rydberg states converging to C 2∑^＋, D ^2∏, and F ^2∏ states of CO^＋, respectively, are confirmed in our spectra. Another peak at around 32eV is assigned to the transition of （3σ）^-1（2π）^1^1∏←X^1∑^＋.
基金Supported by the National Nature Science Foundation of China under Grant No 10604057, and THE National High-Tech Research and Development Program of China under Grant No 2006AA12Z311.
文摘We present an experimental measurement of the lifetime of the cold ^87 Rb atoms in an integrating sphere. The atoms are cooled by the diffuse light which is generated by the diffuse reflection of laser beams in the integrating sphere. Our result shows that the lifetime is primarily determined by the free fall of the cold ^87Rb atoms, and its half-life can reach 40 ms, which is suitable for many experiments, especially for a cold atom clock.
基金Project supported by the National Natural Science Foundation of China （Grant No 10474089）.
文摘The valence-shell excitations of krypton atom have been investigated by fast electron impact with an angle-resolved electron-energy-loss spectrometer. The generalized oscillator strengths for some higher mixed valence-shell excitations in 4d, 4f, 5p, 5d, 6s, 6p, 7s ←4p of krypton atom have been determined. Their profiles are discussed, and the generalized oscillator strengths for the electric monopole and quadrupole excitations in 5p ← 4p are compared with the calculations of Amusia et al. （Phys. Rev. A 67 022703 （2003））. The differences between the experimental results and theoretical calculations show that more studies are needed.
基金Supported by the National Natural Science Foundation of China under Grant No 11604353the Youth Innovation Promotion Association of Chinese Academy of Sciences
文摘The Dick effect is an important factor limiting the frequency stability of sequentially-operating atomic frequency standards. Here we study the impact of the Dick effect in the integrating sphere cold atom clock （ISCAC）. To reduce the impact of the Dick effect, a 5 MHz local oscillator with ultra-low phase noise is selected and a new microwave synthesizer is built in-house. Consequently, the phase noise of microwave signal is optimized. The contribution of the Dick effect is reduced to 2.5× 10^-13τ-1/2 （3- is the integrating time）. The frequency stability of 4.6 × 10-13τ-1/2 is achieved. The development of this optimization can promote the space applications of the compact ISCA C.
