Polarization spectroscopy of the D lines of rubidium atoms is investigated experimentally,especially with different pump powers and cell temperatures.We find that there are four candidate transitions suitable for freq...Polarization spectroscopy of the D lines of rubidium atoms is investigated experimentally,especially with different pump powers and cell temperatures.We find that there are four candidate transitions suitable for frequency stabilization,and optimal pump powers and cell temperatures are also presented to obtain a perfect signal with maximal amplitude and slope.The optimal signal is insensitive to the fluctuations of laser power and the temperature,which can enhance the performance of frequency locking.展开更多
We theoretically investigate quantum phases and transport dynamics of ultracold atoms trapped in an optical lattice in the presence of effective multi-body interaction. When a harmonic external potential is added, sev...We theoretically investigate quantum phases and transport dynamics of ultracold atoms trapped in an optical lattice in the presence of effective multi-body interaction. When a harmonic external potential is added, several interesting phenom- ena are revealed, such as the broadening and the emergence of a central insulator plateau and the phase transition between superftuid and Mott insulator phase. We also study the transport of the system which runs across the superfluid-insulator transition after ramping up the lattice, and predict a slower relaxation which is attributed to the influence of the multi-body interaction on the mass transport.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
Mercury is a promising candidate for the optical lattice clock, due to its low sensitivity to the blackbody radiation. We develop a single folded beam magneto-optical trap for the neutral mercury optical lattice clock...Mercury is a promising candidate for the optical lattice clock, due to its low sensitivity to the blackbody radiation. We develop a single folded beam magneto-optical trap for the neutral mercury optical lattice clock, with a 253. 7nm frequency quadrupled laser. Up to 1.7 × 10^6 （202Hg） or 1.5 × 10^6 （199Hg） atoms can be captured, and the atom temperature is lowered to 170μK （202Hg） or 50μK （199Hg）. The cold atom signals of all six rich abundant isotopes are observed in this system.展开更多
We derive the coupled nonpolynomial nonlinear Schr6dinger equations for a two-component Bose-Lmstem conaensate in a quasi-one-dimension geometry and investigate the effects of a tightly transverse trapping on the grou...We derive the coupled nonpolynomial nonlinear Schr6dinger equations for a two-component Bose-Lmstem conaensate in a quasi-one-dimension geometry and investigate the effects of a tightly transverse trapping on the ground state and the miscibility-immiscibility threshold. We find that the density profile of the matter wavepacket is remarkably dependent on the transverse width and the effective one-dimension nonlinear coupling strengths in miscible and immiscible regimes.展开更多
We report a rapid evaporative cooling method using a hybrid trap which is composed of a quadrupole magnetic trap and a one-beam optical dipole trap. It contains two kinds of evaporative coolings to reach the quantum d...We report a rapid evaporative cooling method using a hybrid trap which is composed of a quadrupole magnetic trap and a one-beam optical dipole trap. It contains two kinds of evaporative coolings to reach the quantum degeneracy： initial radio-frequency （RF） enforced evaporative cooling in the quadrupole magnetic trap and further runaway evaporative cooling in the optical dipole trap. The hybrid trap does not require a very high power laser such as that in the traditional pure optical trap, but still has a deep trap depth and a large trap volume, and has better optical access than the normal magnetic trap like the quadrupole-Ioffe-configuration （QUIC） cloverleaf trap. A high trap frequency can be easily realized in the hybrid trap to enhance the elastic collision rate and shorten the evaporative cooling time. In our experiment, pure Bose-Einstein condensates （BECs） with about 1 x 105 atoms can be realized in 6 s evaporative cooling in the optical dipole trap.展开更多
Light shift is important and inevitably affects the long-term stability of an atomic clock.In this work,considering two unbalanced branches of the spontaneous decay rate in a three-level system,we studied the frequenc...Light shift is important and inevitably affects the long-term stability of an atomic clock.In this work,considering two unbalanced branches of the spontaneous decay rate in a three-level system,we studied the frequency shifts of electromagnetically induced transparency(EIT)and coherent population trapping(CPT)clocks operating under the pulse sequence regime by numerically solving the Liouville density matrix equations.The results show that the frequency shifts are larger when the two branches of spontaneous emission rate are not equal compared to the equal case.In addition,in EIT-Ramsey,the effect of the unbalanced branches of the spontaneous decay rate and relaxations of low-energy states on the frequency shift is greater than that of Rabi frequency.In CPT-Ramsey,the relaxations of low-energy states play a dominant role in frequency shift.展开更多
We investigate the transport dynamics of an interacting binary Bose-Einstein condensate in an incommensurate optical lattice and predict a novel splitting of a matter wavepacket induced by disorder potential and inter...We investigate the transport dynamics of an interacting binary Bose-Einstein condensate in an incommensurate optical lattice and predict a novel splitting of a matter wavepacket induced by disorder potential and inter-species interaction. The effect of atomic interaction on the dynamics of the mobile and localized atoms are also studied in detail. We also discuss the behavior of the balanced and inbalanced mixtures in the incommensurate optical lattice.展开更多
We numerically analyze the dynamic behavior of Bose–Einstein condensate(BEC)in a one-dimensional disordered potential before it completely loses spatial quantum coherence.We find that both the disorder statistics and...We numerically analyze the dynamic behavior of Bose–Einstein condensate(BEC)in a one-dimensional disordered potential before it completely loses spatial quantum coherence.We find that both the disorder statistics and the atom interactions produce remarkable effects on localization.We also find that the single phase of the initial condensate is broken into many small pieces while the system approaches localization,showing a counter-intuitive step-wise phase but not a thoroughly randomized phase.Although the condensates as a whole show less flow and expansion,the currents between adjacent phase steps retain strong time dependence.Thus we show explicitly that the localization of a finite size Bose–Einstein condensate is a dynamic equilibrium state.展开更多
基金Project supported by the Research Project of Shanghai Science and Technology Commission (Grant No. 09DJ1400700)the National 973 Program of China(Grant No. 2011CB921504)the National Natural Science Foundation of China (Grant No. 10974211)
文摘Polarization spectroscopy of the D lines of rubidium atoms is investigated experimentally,especially with different pump powers and cell temperatures.We find that there are four candidate transitions suitable for frequency stabilization,and optimal pump powers and cell temperatures are also presented to obtain a perfect signal with maximal amplitude and slope.The optimal signal is insensitive to the fluctuations of laser power and the temperature,which can enhance the performance of frequency locking.
基金Project supported by the National Basic Research Program of China(Grant No.2011CB921504)the National Natural Science Foundation of China(Grant No.11104292)
文摘We theoretically investigate quantum phases and transport dynamics of ultracold atoms trapped in an optical lattice in the presence of effective multi-body interaction. When a harmonic external potential is added, several interesting phenom- ena are revealed, such as the broadening and the emergence of a central insulator plateau and the phase transition between superftuid and Mott insulator phase. We also study the transport of the system which runs across the superfluid-insulator transition after ramping up the lattice, and predict a slower relaxation which is attributed to the influence of the multi-body interaction on the mass transport.
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Supported by the National Natural Science Foundation of China under Grant No 91436105the National Basic Research Program of China under Grant No 2011CB921504the Research Project of Shanghai Science and Technology Commission under Grant No 09DJ1400700
文摘Mercury is a promising candidate for the optical lattice clock, due to its low sensitivity to the blackbody radiation. We develop a single folded beam magneto-optical trap for the neutral mercury optical lattice clock, with a 253. 7nm frequency quadrupled laser. Up to 1.7 × 10^6 （202Hg） or 1.5 × 10^6 （199Hg） atoms can be captured, and the atom temperature is lowered to 170μK （202Hg） or 50μK （199Hg）. The cold atom signals of all six rich abundant isotopes are observed in this system.
基金supported by the National Natural Science Foundation of China (Grant No. 11104292)the National Basic Research Program of China (Grant No. 2011CB921504)
文摘We derive the coupled nonpolynomial nonlinear Schr6dinger equations for a two-component Bose-Lmstem conaensate in a quasi-one-dimension geometry and investigate the effects of a tightly transverse trapping on the ground state and the miscibility-immiscibility threshold. We find that the density profile of the matter wavepacket is remarkably dependent on the transverse width and the effective one-dimension nonlinear coupling strengths in miscible and immiscible regimes.
基金Project supported by the National Natural Science Foundation of China (Grant No. 10974211)the National Basic Research Program of China (Grant No. 2011CB921504)the Research Project of Shanghai Science and Technology Commission, China (Grant No. 09DJ1400700)
文摘We report a rapid evaporative cooling method using a hybrid trap which is composed of a quadrupole magnetic trap and a one-beam optical dipole trap. It contains two kinds of evaporative coolings to reach the quantum degeneracy： initial radio-frequency （RF） enforced evaporative cooling in the quadrupole magnetic trap and further runaway evaporative cooling in the optical dipole trap. The hybrid trap does not require a very high power laser such as that in the traditional pure optical trap, but still has a deep trap depth and a large trap volume, and has better optical access than the normal magnetic trap like the quadrupole-Ioffe-configuration （QUIC） cloverleaf trap. A high trap frequency can be easily realized in the hybrid trap to enhance the elastic collision rate and shorten the evaporative cooling time. In our experiment, pure Bose-Einstein condensates （BECs） with about 1 x 105 atoms can be realized in 6 s evaporative cooling in the optical dipole trap.
基金Project supported by the State Key Laboratory of Low Dimensional Quantum Physics Research Program,Tsinghua University(Grant No.KF201707).
文摘Light shift is important and inevitably affects the long-term stability of an atomic clock.In this work,considering two unbalanced branches of the spontaneous decay rate in a three-level system,we studied the frequency shifts of electromagnetically induced transparency(EIT)and coherent population trapping(CPT)clocks operating under the pulse sequence regime by numerically solving the Liouville density matrix equations.The results show that the frequency shifts are larger when the two branches of spontaneous emission rate are not equal compared to the equal case.In addition,in EIT-Ramsey,the effect of the unbalanced branches of the spontaneous decay rate and relaxations of low-energy states on the frequency shift is greater than that of Rabi frequency.In CPT-Ramsey,the relaxations of low-energy states play a dominant role in frequency shift.
基金Project supported by the National Natural Science Foundation of China(Grant No.11104292)the National Basic Research Program of China(GrantNo.2011CB921504)
文摘We investigate the transport dynamics of an interacting binary Bose-Einstein condensate in an incommensurate optical lattice and predict a novel splitting of a matter wavepacket induced by disorder potential and inter-species interaction. The effect of atomic interaction on the dynamics of the mobile and localized atoms are also studied in detail. We also discuss the behavior of the balanced and inbalanced mixtures in the incommensurate optical lattice.
基金Supported by the National Natural Science Foundation of China under Grant No.10974211the National Basic Research Program of China under Grant No.2011CB921504the Research Project of Shanghai Science and Technology Commission under Grant Nos.09DJ1400700 and 10DJ1400600.
文摘We numerically analyze the dynamic behavior of Bose–Einstein condensate(BEC)in a one-dimensional disordered potential before it completely loses spatial quantum coherence.We find that both the disorder statistics and the atom interactions produce remarkable effects on localization.We also find that the single phase of the initial condensate is broken into many small pieces while the system approaches localization,showing a counter-intuitive step-wise phase but not a thoroughly randomized phase.Although the condensates as a whole show less flow and expansion,the currents between adjacent phase steps retain strong time dependence.Thus we show explicitly that the localization of a finite size Bose–Einstein condensate is a dynamic equilibrium state.
