We report the production of^(39) K and^(87) Rb Bose–Einstein condensates(BECs) in the lowest hyperfine states |F =1, m_(F) = 1 simultaneously. We collect atoms in bright/dark magneto-optical traps(MOTs) of^(39) K/^(8...We report the production of^(39) K and^(87) Rb Bose–Einstein condensates(BECs) in the lowest hyperfine states |F =1, m_(F) = 1 simultaneously. We collect atoms in bright/dark magneto-optical traps(MOTs) of^(39) K/^(87) Rb to overcome the light-assisted losses of^(39) K atoms. Gray molasses cooling on the D1 line of the^(39) K is used to effectively increase the phase density, which improves the loading efficiency of^(39) K into the quadrupole magnetic trap. Simultaneously, the normal molasses is employed for^(87) Rb. After the microwave evaporation cooling on^(87) Rb in the optically plugged magnetic trap,the atoms mixture is transferred to a crossed optical dipole trap, where the collisional properties of the two species in different combinations of the hyperfine states are studied. The dual species BECs of^(39) K and^(87) Rb are obtained by further evaporative cooling in an optical dipole trap at a magnetic field of 372.6 G with the background repulsive interspecies scattering length a_(KRb)= 34 a_(0)(a_(0) is the Bohr radius) and the intraspecies scattering length a_K= 20.05 a_(0).展开更多
We present a general machine learning based scheme to optimize experimental control.The method utilizes the neural network to learn the relation between the control parameters and the control goal,with which the optim...We present a general machine learning based scheme to optimize experimental control.The method utilizes the neural network to learn the relation between the control parameters and the control goal,with which the optimal control parameters can be obtained.The main challenge of this approach is that the labeled data obtained from experiments are not abundant.The central idea of our scheme is to use the active learning to overcome this difficulty.As a demonstration example,we apply our method to control evaporative cooling experiments in cold atoms.We have first tested our method with simulated data and then applied our method to real experiments.It is demonstrated that our method can successfully reach the best performance within hundreds of experimental runs.Our method does not require knowledge of the experimental system as a prior and is universal for experimental control in different systems.展开更多
We study the electromagnetically induced-absorption-like(EIA-like) effect for an n-type system in an ^(87)Rb Bose–Einstein condensate(BEC) using the absorption imaging technique for coupling and driving lasers operat...We study the electromagnetically induced-absorption-like(EIA-like) effect for an n-type system in an ^(87)Rb Bose–Einstein condensate(BEC) using the absorption imaging technique for coupling and driving lasers operating at the D_1 and D_2 lines of ^(87)Rb. The coherent effect is probed by measuring the number of atoms remaining after the BEC is exposed to strong driving fields and a weak probe field. The absorption imaging technique accurately reveals the EIA-like effect of the n-type system. This coherent effect in an n-type system is useful for optical storage, tunable optical switching, and so on.展开更多
基金supported by the National Key R&D Program of China (Grants Nos. 2016YFA0301602 and 2018YFA0307601)the National Natural Science Foundation of China (Grant Nos. 11974224, 11704234, 11804203, 12034011, 12022406, 12004229, and 92065108)+1 种基金the Fund for Shanxi “1331 Project” Key Subjects Constructionthe Program of Youth Sanjin Scholar。
文摘We report the production of^(39) K and^(87) Rb Bose–Einstein condensates(BECs) in the lowest hyperfine states |F =1, m_(F) = 1 simultaneously. We collect atoms in bright/dark magneto-optical traps(MOTs) of^(39) K/^(87) Rb to overcome the light-assisted losses of^(39) K atoms. Gray molasses cooling on the D1 line of the^(39) K is used to effectively increase the phase density, which improves the loading efficiency of^(39) K into the quadrupole magnetic trap. Simultaneously, the normal molasses is employed for^(87) Rb. After the microwave evaporation cooling on^(87) Rb in the optically plugged magnetic trap,the atoms mixture is transferred to a crossed optical dipole trap, where the collisional properties of the two species in different combinations of the hyperfine states are studied. The dual species BECs of^(39) K and^(87) Rb are obtained by further evaporative cooling in an optical dipole trap at a magnetic field of 372.6 G with the background repulsive interspecies scattering length a_(KRb)= 34 a_(0)(a_(0) is the Bohr radius) and the intraspecies scattering length a_K= 20.05 a_(0).
基金Supported by the Beijing Outstanding Young Scientist Program(HZ)the National Key R&D Program of China(Grant Nos.2016YFA0301600, 2016YFA0301602, and 2018YFA0307600)the National Natural Science Foundation of China(Grant Nos.11734010 and 11804203)
文摘We present a general machine learning based scheme to optimize experimental control.The method utilizes the neural network to learn the relation between the control parameters and the control goal,with which the optimal control parameters can be obtained.The main challenge of this approach is that the labeled data obtained from experiments are not abundant.The central idea of our scheme is to use the active learning to overcome this difficulty.As a demonstration example,we apply our method to control evaporative cooling experiments in cold atoms.We have first tested our method with simulated data and then applied our method to real experiments.It is demonstrated that our method can successfully reach the best performance within hundreds of experimental runs.Our method does not require knowledge of the experimental system as a prior and is universal for experimental control in different systems.
基金the National Key Research and Development Program of China under Grant No 2016YFA0301602the National Natural Science Foundation of China under Grant Nos 11474188 and 11704234the Fund for Shanxi ‘1331 Project’ Key Subjects Construction,and the Program of Youth Sanjin Scholar
文摘We study the electromagnetically induced-absorption-like(EIA-like) effect for an n-type system in an ^(87)Rb Bose–Einstein condensate(BEC) using the absorption imaging technique for coupling and driving lasers operating at the D_1 and D_2 lines of ^(87)Rb. The coherent effect is probed by measuring the number of atoms remaining after the BEC is exposed to strong driving fields and a weak probe field. The absorption imaging technique accurately reveals the EIA-like effect of the n-type system. This coherent effect in an n-type system is useful for optical storage, tunable optical switching, and so on.
