Recently, there have been great interest and advancement in the field of laser cooling and magneto-optical trapping of molecules. The rich internal structure of molecules naturally lends themselves to extensive and ex...Recently, there have been great interest and advancement in the field of laser cooling and magneto-optical trapping of molecules. The rich internal structure of molecules naturally lends themselves to extensive and exciting applications. In this paper, the radical 138Ba19F, as a promising candidate for laser cooling and magneto-optical trapping, is discussed in detail.The highly diagonal Franck-Condon factors between theX2∑＋1/2and A2∏1/2states are first confirmed with three different methods. Afterwards, with the effective Hamiltonian approach and irreducible tensor theory, the hypertine structure of theX2∑＋1/2state is calculated accurately. A scheme for laser cooling is given clearly. Besides, the Zeeman effects of the upper （ A2∏1/2）andlower（X2∑＋1/2）levels are also studied, and their respective g factors are obtained under a weak magnetic field. Its large g factor of the upper stateA2∏1/2is advantageous for magneto-optical trapping. Finally, by studying Stark effect of BaFin theX2∑＋1/2, we investigate the dependence of the internal effective electric field on the applied electric field. It is suggested that such a laser-cooled BaF is also a promising candidate for precision measurement of electron electric dipole moment.展开更多
This paper presents an experimental demonstration of light-induced evaporative cooling in a magneto-optical trap. An additional laser is used to interact with atoms at the edge of the atomic cloud in the trap. These a...This paper presents an experimental demonstration of light-induced evaporative cooling in a magneto-optical trap. An additional laser is used to interact with atoms at the edge of the atomic cloud in the trap. These atoms get an additional force and evaporated away from the trap by both the magnetic field and laser fields. The remaining atoms have lower kinetic energy and thus are cooled. It reports the measurements on the temperature and atomic number after the evaporative cooling with different parameters including the distance between the laser and the centre of the atomic cloud, the detuning, the intensity. The results show that the light-induced evaporative cooling is a way to generate an ultra-cold atom source.展开更多
Atomic physics is developed by the realization of Magneto-Optical Trap (MOT)[1] which helps scientists achievethe miracles of Bose Einstein condensation[2], atomic frequency standard[3] and ultra-cold plasma[4]. We bu...Atomic physics is developed by the realization of Magneto-Optical Trap (MOT)[1] which helps scientists achievethe miracles of Bose Einstein condensation[2], atomic frequency standard[3] and ultra-cold plasma[4]. We built arubidium MOT system and used it to cool and trap as many as 106 87Rb atoms with a density of 1010cm?3 and atemperature of 500 K.The MOT consists of three systems: the vacuum system, the laser system and the control system. The vacuumsystem is carefully designed to obtain a vacuum as high as 510?9 mbar. Rubidium atoms are evaporated intothe vacuum chamber by heating the pure rubidium metal to 40?C.展开更多
A cold atom source is important for quantum metrology and precision measurement.To reduce the quantum projection noise limit in optical lattice clock,one can increase the number of cold atoms and reduce the dead time ...A cold atom source is important for quantum metrology and precision measurement.To reduce the quantum projection noise limit in optical lattice clock,one can increase the number of cold atoms and reduce the dead time by enhancing the loading rate.In this work,we realize an enhanced cold mercury atom source based on a two-dimensional(2D)magnetooptical trap(MOT).The vacuum system is composed of two titanium chambers connected with a differential pumping tube.Two stable cooling laser systems are adopted for the 2D-MOT and the three-dimensional(3D)-MOT,respectively.Using an optimized 2D-MOT and push beam,about 1.3×10^(6)atoms,which are almost an order of magnitude higher than using a pure 3D-MOT,are loaded into the 3D-MOT for202Hg atoms.This enhanced cold mercury atom source is helpful in increasing the frequency stability of a neutral mercury lattice clock.展开更多
We report a detailed study of the enhanced optical molasses cooling of Cs atoms,whose large hyperfine structure allows to use the largely red-detuned cooling lasers.We find that the combination of a large frequency de...We report a detailed study of the enhanced optical molasses cooling of Cs atoms,whose large hyperfine structure allows to use the largely red-detuned cooling lasers.We find that the combination of a large frequency detuning of about-110 MHz for the cooling laser and a suitable control for the powers of the cooling and repumping lasers allows to reach a cold temperature of^5.5μK.We obtain 5.1×10^7 atoms with the number density around 1×10^12 cm^-3.Our result gains a lower temperature than that got in other experiments,in which the cold Cs atoms with the temperature of^10μK have been achieved by the optical molasses cooling.展开更多
Realizing a molecular magneto-optical trap has been a dream for cold molecular physicists for a long time. However,due to the complex energy levels and the small effective Lande g-factor of the excited states, the tra...Realizing a molecular magneto-optical trap has been a dream for cold molecular physicists for a long time. However,due to the complex energy levels and the small effective Lande g-factor of the excited states, the traditional magneto-optical trap（MOT） scheme does not work very well for polar molecules. One way to overcome this problem is the switching MOT,which requires very fast switching of both the magnetic field and the laser polarizations. Switching laser polarizations is relatively easy, but fast switching of the magnetic field is experimentally challenging. Here we propose an alternative approach, the microwave-mediated MOT, which requires a slight change of the current experimental setup to solve the problem. We calculate the MOT force and compare it with the traditional MOT and the switching MOT scheme. The results show that we can operate a good MOT with this simple setup.展开更多
We present a sub-Doppler cooling scheme of a two-trapped-ion crystal by quantum feedback control method. In the scheme, we obtain the motional information by continuously measuring the spontaneous emission photons fro...We present a sub-Doppler cooling scheme of a two-trapped-ion crystal by quantum feedback control method. In the scheme, we obtain the motional information by continuously measuring the spontaneous emission photons from one single ion of the crystal, and then apply a feedback force to cool the whole chain down.We derive the cooling dynamics of the cooling scheme using quantum feedback theory and quantum regression theorem. The result shows that with experimentally achievable parameters, our scheme can achieve lower temperature and faster cooling rate than Doppler cooling.展开更多
Experiments on trapping ytterbium atoms in various optical lattices are presented. After the two-stage cooling, first in a blue magneto-optical trap and then in a green magneto-optical trap, the ultracold 171 Yb atoms...Experiments on trapping ytterbium atoms in various optical lattices are presented. After the two-stage cooling, first in a blue magneto-optical trap and then in a green magneto-optical trap, the ultracold 171 Yb atoms are successfully loaded into one-, two-, and three-dimensional optical lattices operating at the Stark-free wavelength, respectively. The temperature, number, and lifetime of cold 171 Yb atoms in one-dimensional lattice are measured. After optimization, the one-dimensional lattice with cold 171Yb atoms is used for developing an ytterbium optical clock.展开更多
We report on a research of the loading of ultracold sodium atoms in an optical dipole trap,generated by two beams from a high power fiber laser.The effects of optical trap light power on atomic number,temperature and ...We report on a research of the loading of ultracold sodium atoms in an optical dipole trap,generated by two beams from a high power fiber laser.The effects of optical trap light power on atomic number,temperature and phase space density are experimentally investigated.A simple theory is proposed and it is in good accordance with the experimental results of the loaded atomic numbers.In a general estimation,an optimal value for each beam with a power of 9 W from the fiber laser is achieved.Our results provide a further understanding of the loading process of optical dipole trap and laid the foundation for generation of a sodium Bose–Einstein condensation with an optical dipole trap.展开更多
Due to its low sensitivity to blackbody radiation, neutral mercury is a good candidate for the most accurate optical lattice clock. Here we report the observation of cold mercury atoms in a magneto-optical trap （MOT...Due to its low sensitivity to blackbody radiation, neutral mercury is a good candidate for the most accurate optical lattice clock. Here we report the observation of cold mercury atoms in a magneto-optical trap （MOT）. Because of the high vapor pressure at room temperature, the mercury source and the cold pump were cooled down to 40℃ and 70 ℃, respectively, to keep the science chamber in an ultra-high vacuum of 6×10^-9 Pa. Limited by the power of the UV cooling laser, the one beam folded MOT configuration was adopted, and 1.5×10^5 Hg-202 atoms were observed by fluorescence detection.展开更多
A cloud of 40Ca+is successfully trapped and cooled using the radiation of a red-detuned 397 nm laser beam and a resonant 866 nm laser beam in our prototype linear ion trap,which was designed and constructed for studyi...A cloud of 40Ca+is successfully trapped and cooled using the radiation of a red-detuned 397 nm laser beam and a resonant 866 nm laser beam in our prototype linear ion trap,which was designed and constructed for studying quantum information processing.We have characterized the size of the ion cloud,estimating the temperature to be in the order of milli-Kelvins.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant Nos.91536218,11374100,10904037,10974055,11034002,and 11274114)the National Key Basic Research and Development Program of China(Grant No.2011CB921602)the Natural Science Foundation of Shanghai Municipality,China(Grant No.13ZR1412800)
文摘Recently, there have been great interest and advancement in the field of laser cooling and magneto-optical trapping of molecules. The rich internal structure of molecules naturally lends themselves to extensive and exciting applications. In this paper, the radical 138Ba19F, as a promising candidate for laser cooling and magneto-optical trapping, is discussed in detail.The highly diagonal Franck-Condon factors between theX2∑＋1/2and A2∏1/2states are first confirmed with three different methods. Afterwards, with the effective Hamiltonian approach and irreducible tensor theory, the hypertine structure of theX2∑＋1/2state is calculated accurately. A scheme for laser cooling is given clearly. Besides, the Zeeman effects of the upper （ A2∏1/2）andlower（X2∑＋1/2）levels are also studied, and their respective g factors are obtained under a weak magnetic field. Its large g factor of the upper stateA2∏1/2is advantageous for magneto-optical trapping. Finally, by studying Stark effect of BaFin theX2∑＋1/2, we investigate the dependence of the internal effective electric field on the applied electric field. It is suggested that such a laser-cooled BaF is also a promising candidate for precision measurement of electron electric dipole moment.
基金Project supported by the Shanghai Pujiang Programme and the National Basic Research Programme of China (Grant No 2005CB724506)the National Natural Science Foundation of China (Grant No 10604057)
文摘This paper presents an experimental demonstration of light-induced evaporative cooling in a magneto-optical trap. An additional laser is used to interact with atoms at the edge of the atomic cloud in the trap. These atoms get an additional force and evaporated away from the trap by both the magnetic field and laser fields. The remaining atoms have lower kinetic energy and thus are cooled. It reports the measurements on the temperature and atomic number after the evaporative cooling with different parameters including the distance between the laser and the centre of the atomic cloud, the detuning, the intensity. The results show that the light-induced evaporative cooling is a way to generate an ultra-cold atom source.
文摘Atomic physics is developed by the realization of Magneto-Optical Trap (MOT)[1] which helps scientists achievethe miracles of Bose Einstein condensation[2], atomic frequency standard[3] and ultra-cold plasma[4]. We built arubidium MOT system and used it to cool and trap as many as 106 87Rb atoms with a density of 1010cm?3 and atemperature of 500 K.The MOT consists of three systems: the vacuum system, the laser system and the control system. The vacuumsystem is carefully designed to obtain a vacuum as high as 510?9 mbar. Rubidium atoms are evaporated intothe vacuum chamber by heating the pure rubidium metal to 40?C.
文摘A cold atom source is important for quantum metrology and precision measurement.To reduce the quantum projection noise limit in optical lattice clock,one can increase the number of cold atoms and reduce the dead time by enhancing the loading rate.In this work,we realize an enhanced cold mercury atom source based on a two-dimensional(2D)magnetooptical trap(MOT).The vacuum system is composed of two titanium chambers connected with a differential pumping tube.Two stable cooling laser systems are adopted for the 2D-MOT and the three-dimensional(3D)-MOT,respectively.Using an optimized 2D-MOT and push beam,about 1.3×10^(6)atoms,which are almost an order of magnitude higher than using a pure 3D-MOT,are loaded into the 3D-MOT for202Hg atoms.This enhanced cold mercury atom source is helpful in increasing the frequency stability of a neutral mercury lattice clock.
基金Project supported by the National Key Research and Development Program of China(Grant No.2017YFA0304203)the National Natural Science Foundation of China(Grant Nos.61722507,61675121,and 61705123)+4 种基金PCSIRT(Grant No.IRT17R70)the 111 Project(Grant No.D18001)the Shanxi 1331 KSC,the Program for the Outstanding Innovative Teams of Higher Learning Institutions of Shanxi(OIT),the Applied Basic Research Project of Shanxi Province,China(Grant No.201701D221002)the Fund Program for the Scientific Activities of Selected Returned Overseas Professionals in Shanxi Provincethe Open Research Fund Program of the State Key Laboratory of Low-Dimensional Quantum Physics.
文摘We report a detailed study of the enhanced optical molasses cooling of Cs atoms,whose large hyperfine structure allows to use the largely red-detuned cooling lasers.We find that the combination of a large frequency detuning of about-110 MHz for the cooling laser and a suitable control for the powers of the cooling and repumping lasers allows to reach a cold temperature of^5.5μK.We obtain 5.1×10^7 atoms with the number density around 1×10^12 cm^-3.Our result gains a lower temperature than that got in other experiments,in which the cold Cs atoms with the temperature of^10μK have been achieved by the optical molasses cooling.
基金Project supported by the Fundamental Research Funds for the Central Universities of China
文摘Realizing a molecular magneto-optical trap has been a dream for cold molecular physicists for a long time. However,due to the complex energy levels and the small effective Lande g-factor of the excited states, the traditional magneto-optical trap（MOT） scheme does not work very well for polar molecules. One way to overcome this problem is the switching MOT,which requires very fast switching of both the magnetic field and the laser polarizations. Switching laser polarizations is relatively easy, but fast switching of the magnetic field is experimentally challenging. Here we propose an alternative approach, the microwave-mediated MOT, which requires a slight change of the current experimental setup to solve the problem. We calculate the MOT force and compare it with the traditional MOT and the switching MOT scheme. The results show that we can operate a good MOT with this simple setup.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11504430,61205108,and 11304387)the National Key R&D Program of China(Grant No.2016YFA0301903)
文摘We present a sub-Doppler cooling scheme of a two-trapped-ion crystal by quantum feedback control method. In the scheme, we obtain the motional information by continuously measuring the spontaneous emission photons from one single ion of the crystal, and then apply a feedback force to cool the whole chain down.We derive the cooling dynamics of the cooling scheme using quantum feedback theory and quantum regression theorem. The result shows that with experimentally achievable parameters, our scheme can achieve lower temperature and faster cooling rate than Doppler cooling.
基金Project supported by the National Key Basic Research and Development Program of China (Grant Nos.2012CB821302 and 2010CB922903)the National Natural Science Foundation of China (Grant Nos.11134003 and 10774044)the Shanghai Excellent Academic Leaders Program of China (Grant No.12XD1402400)
文摘Experiments on trapping ytterbium atoms in various optical lattices are presented. After the two-stage cooling, first in a blue magneto-optical trap and then in a green magneto-optical trap, the ultracold 171 Yb atoms are successfully loaded into one-, two-, and three-dimensional optical lattices operating at the Stark-free wavelength, respectively. The temperature, number, and lifetime of cold 171 Yb atoms in one-dimensional lattice are measured. After optimization, the one-dimensional lattice with cold 171Yb atoms is used for developing an ytterbium optical clock.
基金Project supported by the National Key R&D Program of China(Grant No.2017YFA0304203)the National Natural Science Foundation of China(Grant Nos.61722507,61675121,61705123,62020106014,and 62011530047)+4 种基金the PCSIRT(Grant No.IRT-17R70)the 111 Project(Grant No.D18001)the Program for the Outstanding Innovative Teams of Higher Learning Institutions of Shanxi(OIT)the Applied Basic Research Project of Shanxi Province,China(Grant Nos.201801D221004,201901D211191,and 201901D211188)the Shanxi 1331 KSC.
文摘We report on a research of the loading of ultracold sodium atoms in an optical dipole trap,generated by two beams from a high power fiber laser.The effects of optical trap light power on atomic number,temperature and phase space density are experimentally investigated.A simple theory is proposed and it is in good accordance with the experimental results of the loaded atomic numbers.In a general estimation,an optimal value for each beam with a power of 9 W from the fiber laser is achieved.Our results provide a further understanding of the loading process of optical dipole trap and laid the foundation for generation of a sodium Bose–Einstein condensation with an optical dipole trap.
基金Project supported by the Research Project of Shanghai Science and Technology Commission, China (Grant No. 09DJ1400700)the National Natural Science Foundation of China (Grant Nos. 10974211 and 11104292)the National Basic Research Program of China (Grant No. 2011CB921504)
文摘Due to its low sensitivity to blackbody radiation, neutral mercury is a good candidate for the most accurate optical lattice clock. Here we report the observation of cold mercury atoms in a magneto-optical trap （MOT）. Because of the high vapor pressure at room temperature, the mercury source and the cold pump were cooled down to 40℃ and 70 ℃, respectively, to keep the science chamber in an ultra-high vacuum of 6×10^-9 Pa. Limited by the power of the UV cooling laser, the one beam folded MOT configuration was adopted, and 1.5×10^5 Hg-202 atoms were observed by fluorescence detection.
基金supported by the National Natural Science Foundation of China(10774163,10974225)the National Basic Research Program of China(2006CB921203)
文摘A cloud of 40Ca+is successfully trapped and cooled using the radiation of a red-detuned 397 nm laser beam and a resonant 866 nm laser beam in our prototype linear ion trap,which was designed and constructed for studying quantum information processing.We have characterized the size of the ion cloud,estimating the temperature to be in the order of milli-Kelvins.
