We measure the signal amplitude and linewidth of a dark line in coherent population trapping in the Rb vapour cell filled with mixed buffer gas N2 and Ar as a function of cell temperature. We find that the dark line s...We measure the signal amplitude and linewidth of a dark line in coherent population trapping in the Rb vapour cell filled with mixed buffer gas N2 and Ar as a function of cell temperature. We find that the dark line signal amplitude increases with temperature up to a maximum at 49℃ and then drops at higher temperatures due to quenching effects of N2. The linewidth of the dark line remains basically constant, at 1080 Hz. We also measure the linewidth of the dark line as a function of laser intensity. The linewidth increases linearly with laser intensity. An intrinsic linewidth （FWHM=896 Hz at 3.4 GHz） of the Rb cell is obtained.展开更多
This paper investigates the absorptive spectral lines of four-level atomic system driven by a coupling, probe and microwave fields. Due to the perturbation of the microwave field, the original electromagnetically indu...This paper investigates the absorptive spectral lines of four-level atomic system driven by a coupling, probe and microwave fields. Due to the perturbation of the microwave field, the original electromagnetically induced transparency is changed to electromagnetically induced absorption and the absorptive spectral line can be very narrow. This ultranarrow spectral line has potential applications to the microwave atomic frequency standard and the measurement of very weak magnetic field.展开更多
We have investigated the dispersive properties of excited-doublet four-level atoms interacting with a weak probe field and an intense coupling laser field. We have derived an analytical expression of the dispersion re...We have investigated the dispersive properties of excited-doublet four-level atoms interacting with a weak probe field and an intense coupling laser field. We have derived an analytical expression of the dispersion relation for a general excited-doublet four-level atomic system subject to a one-photon detuning. The numerical results demonstrate that for a typical rubidium D1 line configuration, due to the unequal dipole moments for the transitions of each ground state to double excited states, generally there exists no exact dark state in the system. Close to the two-photon resonance, the probe light can be absorbed or gained and propagate in the so-called superluminal form. This system may be used as an optical switch.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
Transient coherent oscillations in a closed A system under far-off resonant Raman fields were investigated theoreti- cally. It has been found that the coherent superposition of the ground states can be formed due to t...Transient coherent oscillations in a closed A system under far-off resonant Raman fields were investigated theoreti- cally. It has been found that the coherent superposition of the ground states can be formed due to the absorption even for initial maximal mixed ground states. The absorption oscillates with a period depending on the two-photon detuning when the system is initially in a transparent state and the two-photon Raman detuning is suddenly changed. The amplitude of the absorption decays with the decay rate of the ground states, which is different from the case when the lasers are applied resonantly. These transient coherent oscillations can be used to measure the relaxation rate of the ground states.展开更多
This paper theoretically investigates the microwave transition spectrum of STRb atomic D1 line with specially prepared atomic state in a Hanle configuration. The approximate analytical results have shown that the 0-0 ...This paper theoretically investigates the microwave transition spectrum of STRb atomic D1 line with specially prepared atomic state in a Hanle configuration. The approximate analytical results have shown that the 0-0 transition spectral line has the highest contrast and can be applied to microwave frequency standards.展开更多
We theoretically investigate an open four-level atomic system interacting with control,probe and microwave fields.When there is no repumping light and a microwave field is applied,the probe light can be absorbed or am...We theoretically investigate an open four-level atomic system interacting with control,probe and microwave fields.When there is no repumping light and a microwave field is applied,the probe light can be absorbed or amplified,which has different features than those of a system whose populations are pumped into only one ground state.In this system the microwave field and the population distributions of the ground states can be used as switches to control the propagation of the probe light.展开更多
High contrast transparent Ramsey fringes are observed using double microwave pulses interaction with the prepared atomic coherent state in a warm STRb vapor with mixture buffer gases in a closed cell. The Ramsey fring...High contrast transparent Ramsey fringes are observed using double microwave pulses interaction with the prepared atomic coherent state in a warm STRb vapor with mixture buffer gases in a closed cell. The Ramsey fringes are generated by the pulsed technique, a strong coupling light pulse and a weak signal light pulse are applied to prepare the atomic coherent state, followed by the application of double microwave pulses to interact with the atomic coherent state. Afterwards, the light pulses are applied again with weaker intensity and detecting the signal transmission is delected. The central line of the transparent Ramsey fringes has narrow linewidth of 125 Hz and high contrast of 21%. The light shift is dramatically reduced since the interrogating process is not involved the light field, and the cavity pulling effect is negligible due to the low Q requirement, which is promising for building small, compact, and stable atomic clocks.展开更多
We report the recent progress of our pulsed optically pumped（POP） vapor cell rubidium clock with dispersive detection.A new compact physics package is made.A rubidium cell with a high precision buffer gases mixing r...We report the recent progress of our pulsed optically pumped（POP） vapor cell rubidium clock with dispersive detection.A new compact physics package is made.A rubidium cell with a high precision buffer gases mixing ratio is obtained,and the temperature controlling system is renovated to reduce fractional frequency sensitivity to temperature variation.The resolution of the servo control voltage is also optimized.With these improvements,a clock frequency stability of 3.53×10-13 at 1s is obtained,and a fractional frequency stability of 4.91×10-15 is achieved at an average time of τ=2000 s.展开更多
We report an experimental observation of the optical transparency enhancement resonances in Hanle- electromagnetically induced transparency （EIT） configuration with a microwave field excitation. In this experimental...We report an experimental observation of the optical transparency enhancement resonances in Hanle- electromagnetically induced transparency （EIT） configuration with a microwave field excitation. In this experimental system, a strong control field and a weak probe field form three-level A-type configurations of EIT. The fourth level is coupled by an additional microwave field. With the microwave field excitation, the probe field undergoes a process of absorption to transparency when the probe field decreases. Compared with the EIT effect, this result indicates optical transparency enhancement. A simple theoretical model and a numerical simulation are presented to explain the observed experimental results. The applications of these optical features are also discussed.展开更多
文摘We measure the signal amplitude and linewidth of a dark line in coherent population trapping in the Rb vapour cell filled with mixed buffer gas N2 and Ar as a function of cell temperature. We find that the dark line signal amplitude increases with temperature up to a maximum at 49℃ and then drops at higher temperatures due to quenching effects of N2. The linewidth of the dark line remains basically constant, at 1080 Hz. We also measure the linewidth of the dark line as a function of laser intensity. The linewidth increases linearly with laser intensity. An intrinsic linewidth （FWHM=896 Hz at 3.4 GHz） of the Rb cell is obtained.
基金Project supported by the Knowledge Innovation Program (KIP) of the Chinese Academy of Sciences(Grant No KGCX3-SYW-405)the State Key Development Program for Basic Research of China(Grant Nos 2005CB724507 and 2006CB921202)
文摘This paper investigates the absorptive spectral lines of four-level atomic system driven by a coupling, probe and microwave fields. Due to the perturbation of the microwave field, the original electromagnetically induced transparency is changed to electromagnetically induced absorption and the absorptive spectral line can be very narrow. This ultranarrow spectral line has potential applications to the microwave atomic frequency standard and the measurement of very weak magnetic field.
基金supported by the Knowledge Innovation Program (KIP) of the Chinese Academy of Sciences (Grant No KGCX3-SYW-405)the National Fundamental Research Program of China (Grant Nos 2005CB724507 and 2006CB921202)
文摘We have investigated the dispersive properties of excited-doublet four-level atoms interacting with a weak probe field and an intense coupling laser field. We have derived an analytical expression of the dispersion relation for a general excited-doublet four-level atomic system subject to a one-photon detuning. The numerical results demonstrate that for a typical rubidium D1 line configuration, due to the unequal dipole moments for the transitions of each ground state to double excited states, generally there exists no exact dark state in the system. Close to the two-photon resonance, the probe light can be absorbed or gained and propagate in the so-called superluminal form. This system may be used as an optical switch.
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Project supported by the Knowledge Innovation Program of the Chinese Academy of Sciences and the National Basic Research Program of China
文摘Transient coherent oscillations in a closed A system under far-off resonant Raman fields were investigated theoreti- cally. It has been found that the coherent superposition of the ground states can be formed due to the absorption even for initial maximal mixed ground states. The absorption oscillates with a period depending on the two-photon detuning when the system is initially in a transparent state and the two-photon Raman detuning is suddenly changed. The amplitude of the absorption decays with the decay rate of the ground states, which is different from the case when the lasers are applied resonantly. These transient coherent oscillations can be used to measure the relaxation rate of the ground states.
基金supported by the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KGCX3-SYW-405)the National Fundamental Research Program of China (Grant Nos. 2005CB724507 and 2006CB921202)
文摘This paper theoretically investigates the microwave transition spectrum of STRb atomic D1 line with specially prepared atomic state in a Hanle configuration. The approximate analytical results have shown that the 0-0 transition spectral line has the highest contrast and can be applied to microwave frequency standards.
基金Supported by the Knowledge Innovation Program of Chinese Academy of Sciences under Grant No KGCX3-SYW-405the State Key Development Program for Basic Research(KGCX3-SYW-405)+1 种基金the National Basic Research Program of China under Grant Nos 2005CB724507 and 2006CB921202National Natural Science Foundation of China(10974210).
文摘We theoretically investigate an open four-level atomic system interacting with control,probe and microwave fields.When there is no repumping light and a microwave field is applied,the probe light can be absorbed or amplified,which has different features than those of a system whose populations are pumped into only one ground state.In this system the microwave field and the population distributions of the ground states can be used as switches to control the propagation of the probe light.
基金supported by the Major State Basic Research Development Program of China under Grant No.2005CB724507
文摘High contrast transparent Ramsey fringes are observed using double microwave pulses interaction with the prepared atomic coherent state in a warm STRb vapor with mixture buffer gases in a closed cell. The Ramsey fringes are generated by the pulsed technique, a strong coupling light pulse and a weak signal light pulse are applied to prepare the atomic coherent state, followed by the application of double microwave pulses to interact with the atomic coherent state. Afterwards, the light pulses are applied again with weaker intensity and detecting the signal transmission is delected. The central line of the transparent Ramsey fringes has narrow linewidth of 125 Hz and high contrast of 21%. The light shift is dramatically reduced since the interrogating process is not involved the light field, and the cavity pulling effect is negligible due to the low Q requirement, which is promising for building small, compact, and stable atomic clocks.
基金supported by the National Natural Science Foundation of China under Grant Nos.91536220 and 11504393
文摘We report the recent progress of our pulsed optically pumped（POP） vapor cell rubidium clock with dispersive detection.A new compact physics package is made.A rubidium cell with a high precision buffer gases mixing ratio is obtained,and the temperature controlling system is renovated to reduce fractional frequency sensitivity to temperature variation.The resolution of the servo control voltage is also optimized.With these improvements,a clock frequency stability of 3.53×10-13 at 1s is obtained,and a fractional frequency stability of 4.91×10-15 is achieved at an average time of τ=2000 s.
基金supported by the Major State Basic Research Development Program of China under Grant No.2005CB724507
文摘We report an experimental observation of the optical transparency enhancement resonances in Hanle- electromagnetically induced transparency （EIT） configuration with a microwave field excitation. In this experimental system, a strong control field and a weak probe field form three-level A-type configurations of EIT. The fourth level is coupled by an additional microwave field. With the microwave field excitation, the probe field undergoes a process of absorption to transparency when the probe field decreases. Compared with the EIT effect, this result indicates optical transparency enhancement. A simple theoretical model and a numerical simulation are presented to explain the observed experimental results. The applications of these optical features are also discussed.
