We present a theoretical approach to achieve sub-Doppler cooling of magnesium fluoride(Mg F) molecules by tuning the AC Stark shift with a blue-detuned laser. We study three blue-detuned magneto–optical trapping(MOT)...We present a theoretical approach to achieve sub-Doppler cooling of magnesium fluoride(Mg F) molecules by tuning the AC Stark shift with a blue-detuned laser. We study three blue-detuned magneto–optical trapping(MOT) schemes by using the Bayesian optimization method with the optical Bloch equations. We perform a comprehensive analysis of the relationship between the force in the MOT and the velocities and positions of the Mg F molecules. Monte–Carlo simulations show that our MOT schemes can achieve a temperature as low as 28 μK and a density as high as 4.0 × 10^(8)cm^(-3) at the conditions of a ratio of two laser intensities of 2:7, a detuning of 3Γ and a polarization configuration of σ^(-)-σ^(+). These results provide a clear way for transferring a large number of Mg F molecules into a conservative trap to enhance the subsequent cooling such as evaporative or sympathetic cooling.展开更多
With a coupling laser locked to caesium 6S1/2 Fg=4-6P3/2 Fe=5 cycling transition and a co-propagating probe laser scanned across 6S1/2 Fg=4-6Pa/2 Fe=3, 4 and 5 transitions, a novel scheme for sub-Doppler spectra in Do...With a coupling laser locked to caesium 6S1/2 Fg=4-6P3/2 Fe=5 cycling transition and a co-propagating probe laser scanned across 6S1/2 Fg=4-6Pa/2 Fe=3, 4 and 5 transitions, a novel scheme for sub-Doppler spectra in Dopplerbroadened V-type three-level system is demonstrated by detecting the transmission of the coupling laser through a caesium vapour cell. The Autler-Townes doublet in the sub-Doppler spectra of the coupling laser is clearly observed. The effects of coupling laser intensity on the splitting and linewidth of the Autler-Townes doublet are experimentally investigated and the results agree well with theoretical predictions. Taking the multiple hyperfine levels of caesium atom into account, a brief analysis is presented.展开更多
We report on the efficient gray molasses cooling of sodium atoms using the D2 optical transition at 589.1 nm.Thanks to the hyperfine split about 6Γ between |F’ = 2> and |F’ = 3> in the excited state 32 P3/2, ...We report on the efficient gray molasses cooling of sodium atoms using the D2 optical transition at 589.1 nm.Thanks to the hyperfine split about 6Γ between |F’ = 2> and |F’ = 3> in the excited state 32 P3/2, this atomic transition is effective for the gray molasses cooling mechanism. Using this cooling technique, the atomic sample in F = 2 ground manifold is cooled from 700 μK to 56 μK in 3.5 ms. We observe that the loading efficiency into magnetic trap is increased due to the lower temperature and high phase space density of atomic cloud after gray molasses. This technique offers a promising route for the fast cooling of the sodium atoms in the F = 2 state.展开更多
We demonstrate a non-crossover sub-Doppler dichroic atomic vapor laser locking(DAVLL)in selective reflection scheme,which allows us to obtain a modulation-free laser locking with wide tuneable range.The dependence of ...We demonstrate a non-crossover sub-Doppler dichroic atomic vapor laser locking(DAVLL)in selective reflection scheme,which allows us to obtain a modulation-free laser locking with wide tuneable range.The dependence of peak-to-peak amplitude,tuneable range and the slope near the zero-crossing point of error signal on the frequency shift induced by the magnetic fields are studied.The adjustable error signal by the varying external magnetic field can offer the laser locking from the order of tens MHz to hundreds MHz.The ultimate dither of locked laser frequency is less than 0.5 MHz.The square root of Allan variance of the error signals reaches a minimum of 3×10^(-10)for an averaging time of 130 s.展开更多
The coefficient of selective reflection at oblique incidence from two-level atoms confined between two dielectric walls is calculated in this paper. It is found to be related to the transient behaviour of atoms after ...The coefficient of selective reflection at oblique incidence from two-level atoms confined between two dielectric walls is calculated in this paper. It is found to be related to the transient behaviour of atoms after colliding with the wall and the distribution of the field inside the vapour corresponds to L/λ, with L the thickness of the film and λ the incident wavelength. We find that the sub-Doppler structure is manifest both for normal incidence and small angle oblique incidence, It is feasible to detect the real part of selective reflection in several cases that have not been achieved before.展开更多
Frequency shifts of the acetylene saturated absorption lines at 1.5μm with temperature, gas pressure and laser power have been investigated in detail. The second-order Doppler effect, the recoil effect, the Zeeman ef...Frequency shifts of the acetylene saturated absorption lines at 1.5μm with temperature, gas pressure and laser power have been investigated in detail. The second-order Doppler effect, the recoil effect, the Zeeman effect, the pressure shift and the power shift are taken into consideration. The magnitudes of those shifts caused by various effects are evaluated. In order to reproduce the stability of 5.7 × 10^-14 obtained by Edwards, all necessary conditions are given. The results show that when there is a larger external magnetic field, the Zeeman shift could not be neglected, so that the shield should be employed. And the design of a long cavity is advantageous to reduce the influence of the second-order Doppler effect. The results also show that at least 4-2.5℃ temperature control for cavity can effectively prevent several effects and improve the frequency stability.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 12174115 and 91836103)。
文摘We present a theoretical approach to achieve sub-Doppler cooling of magnesium fluoride(Mg F) molecules by tuning the AC Stark shift with a blue-detuned laser. We study three blue-detuned magneto–optical trapping(MOT) schemes by using the Bayesian optimization method with the optical Bloch equations. We perform a comprehensive analysis of the relationship between the force in the MOT and the velocities and positions of the Mg F molecules. Monte–Carlo simulations show that our MOT schemes can achieve a temperature as low as 28 μK and a density as high as 4.0 × 10^(8)cm^(-3) at the conditions of a ratio of two laser intensities of 2:7, a detuning of 3Γ and a polarization configuration of σ^(-)-σ^(+). These results provide a clear way for transferring a large number of Mg F molecules into a conservative trap to enhance the subsequent cooling such as evaporative or sympathetic cooling.
基金Project supported by the National Natural Science Foundation of China （Grant Nos 60578018, 10434080 and 10374062）, by the Key Scientific Program of Education Ministry of China （Grant No 204019）, and by the Research Funds for Youth Academic Leaders of Shanxi Province, China.
文摘With a coupling laser locked to caesium 6S1/2 Fg=4-6P3/2 Fe=5 cycling transition and a co-propagating probe laser scanned across 6S1/2 Fg=4-6Pa/2 Fe=3, 4 and 5 transitions, a novel scheme for sub-Doppler spectra in Dopplerbroadened V-type three-level system is demonstrated by detecting the transmission of the coupling laser through a caesium vapour cell. The Autler-Townes doublet in the sub-Doppler spectra of the coupling laser is clearly observed. The effects of coupling laser intensity on the splitting and linewidth of the Autler-Townes doublet are experimentally investigated and the results agree well with theoretical predictions. Taking the multiple hyperfine levels of caesium atom into account, a brief analysis is presented.
基金Supported by the National Key Research and Development Program of China under Grant No 2016YFA0301602the National Natural Science Foundation of China under Grant Nos 11474188 and 11704234+1 种基金the National Key Research and Development Program of China under Grant No 2018YFA0307601the Fund for Shanxi ‘1331 Project’ Key Subjects Construction,and the Program of Youth Sanjin Scholar
文摘We report on the efficient gray molasses cooling of sodium atoms using the D2 optical transition at 589.1 nm.Thanks to the hyperfine split about 6Γ between |F’ = 2> and |F’ = 3> in the excited state 32 P3/2, this atomic transition is effective for the gray molasses cooling mechanism. Using this cooling technique, the atomic sample in F = 2 ground manifold is cooled from 700 μK to 56 μK in 3.5 ms. We observe that the loading efficiency into magnetic trap is increased due to the lower temperature and high phase space density of atomic cloud after gray molasses. This technique offers a promising route for the fast cooling of the sodium atoms in the F = 2 state.
基金Project supported by the National Key Research and Development Program of China(Grant Nos.2017YFA0304203 and 2016YFF0200104)the National Natural Science Foundation of China(Grant No.61827824)+1 种基金the Fund from the BAIREN Plan of Shanxi Province,Chinathe Funding for Shanxi“1331 Project”Key Subjects Construction,China
文摘We demonstrate a non-crossover sub-Doppler dichroic atomic vapor laser locking(DAVLL)in selective reflection scheme,which allows us to obtain a modulation-free laser locking with wide tuneable range.The dependence of peak-to-peak amplitude,tuneable range and the slope near the zero-crossing point of error signal on the frequency shift induced by the magnetic fields are studied.The adjustable error signal by the varying external magnetic field can offer the laser locking from the order of tens MHz to hundreds MHz.The ultimate dither of locked laser frequency is less than 0.5 MHz.The square root of Allan variance of the error signals reaches a minimum of 3×10^(-10)for an averaging time of 130 s.
基金Project supported by Science Foundation of Ningxia Higher Education of China （Grant No 2005153）.
文摘The coefficient of selective reflection at oblique incidence from two-level atoms confined between two dielectric walls is calculated in this paper. It is found to be related to the transient behaviour of atoms after colliding with the wall and the distribution of the field inside the vapour corresponds to L/λ, with L the thickness of the film and λ the incident wavelength. We find that the sub-Doppler structure is manifest both for normal incidence and small angle oblique incidence, It is feasible to detect the real part of selective reflection in several cases that have not been achieved before.
基金Project supported by the Provincial Natural Science Funds of Shanxi Province, China (Grant No 20041037)the Industrial R&D Programme of Shanxi Province, China (Grant No 2006031118-04)
文摘Frequency shifts of the acetylene saturated absorption lines at 1.5μm with temperature, gas pressure and laser power have been investigated in detail. The second-order Doppler effect, the recoil effect, the Zeeman effect, the pressure shift and the power shift are taken into consideration. The magnitudes of those shifts caused by various effects are evaluated. In order to reproduce the stability of 5.7 × 10^-14 obtained by Edwards, all necessary conditions are given. The results show that when there is a larger external magnetic field, the Zeeman shift could not be neglected, so that the shield should be employed. And the design of a long cavity is advantageous to reduce the influence of the second-order Doppler effect. The results also show that at least 4-2.5℃ temperature control for cavity can effectively prevent several effects and improve the frequency stability.
