Magneto-optical traps (MOTs) composed of magnetic fields and light fields have been widely utilized to cool andconfine microscopic particles. Practical technology applications require miniaturized MOTs. The advancemen...Magneto-optical traps (MOTs) composed of magnetic fields and light fields have been widely utilized to cool andconfine microscopic particles. Practical technology applications require miniaturized MOTs. The advancement of planaroptics has promoted the development of compact MOTs. In this article, we review the development of compact MOTs basedon planar optics. First, we introduce the standardMOTs. We then introduce the gratingMOTs with micron structures, whichhave been used to build cold atomic clocks, cold atomic interferometers, and ultra-cold sources. Further, we introducethe integrated MOTs based on nano-scale metasurfaces. These new compact MOTs greatly reduce volume and powerconsumption, and provide new opportunities for fundamental research and practical applications.展开更多
We report the production of ^(87)Rb Bose–Einstein condensate in an asymmetric crossed optical dipole trap(ACODT)without the need of an additional dimple laser.In our experiment,the ACODT is formed by two laser beams ...We report the production of ^(87)Rb Bose–Einstein condensate in an asymmetric crossed optical dipole trap(ACODT)without the need of an additional dimple laser.In our experiment,the ACODT is formed by two laser beams with different radii to achieve efficient capture and rapid evaporation of laser cooled atoms.Compared to the cooling procedure in a magnetic trap,the atoms are firstly laser cooled and then directly loaded into an ACODT without the pre-evaporative cooling process.In order to determine the optimal parameters for evaporation cooling,we optimize the power ratio of the two beams and the evaporation time to maximize the final atom number left in the ACODT.By loading about 6×10^(5) laser cooled atoms in the ACODT,we obtain a pure Bose–Einstein condensate with about 1.4×10^(4) atoms after 19 s evaporation.Additionally,we demonstrate that the fringe-type noises in optical density distributions can be reduced via principal component analysis,which correspondingly improves the reliability of temperature measurement.展开更多
The open quantum system can be described by either a Lindblad master equation or a non-Hermitian Hamiltonian(NHH).However,these two descriptions usually have different exceptional points(EPs),associated with the degen...The open quantum system can be described by either a Lindblad master equation or a non-Hermitian Hamiltonian(NHH).However,these two descriptions usually have different exceptional points(EPs),associated with the degeneracies in the open quantum system.Here,considering a dissipative quantum Rabi model,we study the spectral features of EPs in these two descriptions and explore their connections.We find that,although the EPs in these two descriptions are usually different,the EPs of NHH will be consistent with the EPs of master equation in the weak coupling regime.Further,we find that the quantum Fisher information(QFI),which measures the statistical distance between quantum states,can be used as a signature for the appearance of EPs.Our study may give a theoretical guidance for exploring the properties of EPs in open quantum systems.展开更多
Based upon the new designed helical resonator,the resonant radio frequency(RF)for trapping ions can be consec-utively adjusted in a large range(about 12 MHz to 29 MHz)with high Q-factors(above 300).We analyze the heli...Based upon the new designed helical resonator,the resonant radio frequency(RF)for trapping ions can be consec-utively adjusted in a large range(about 12 MHz to 29 MHz)with high Q-factors(above 300).We analyze the helical resonator with a lumped element circuit model and find that the theoretical results fit well with the experimental data.With our resonator system,the resonant frequency near magic RF frequency(where the scalar Stark shift and the second-order Doppler shift due to excess micromotion cancel each other)can be continuously changed at kHz level.For ^(88)Sr^(+) ion,compared to earlier results,the measurement accuracy of magic RF frequency can be improved by an order of magnitude upon rough calculation,and therefore the net micromotion frequency shifts can be further reduced.Also,the differential static scalar polarizability △α0 of clock transition can be experimentally measured more accurately.展开更多
We present a cluster mean-field study for ground-state phase diagram and many-body dynamics of spin-1 bosons confined in a two-chain Bose-Hubbard ladder(BHL).For unbiased BHL,we find superfluid(SF)phase and integer fi...We present a cluster mean-field study for ground-state phase diagram and many-body dynamics of spin-1 bosons confined in a two-chain Bose-Hubbard ladder(BHL).For unbiased BHL,we find superfluid(SF)phase and integer filling Mott insulator(Int MI)phase.For biased BHL,in addition to the SF and Int MI phases,there appears half-integer filling Mott insulator(HInt MI)phase.The phase transition between the SF and Int MI phases can be first order at a part of phase boundaries,while the phase transition between the SF and HInt MI phases is always second order.By tuning the bias energy,we report on the change of the nature of SF-MI phase transitions.Furthermore,we study the effect of the spin-dependent interaction on the many-body population dynamics.The spin-dependent interaction can lead to rich dynamical behaviors,but does not influence the particle transfer efficiency.Our results indicate a way to tune the nature of the SF-MI phase transition and open a new avenue to study the many-body dynamics of spinor bosons in optical lattices.展开更多
基金the National Key Research and Development Program of China(Grant No.2022YFA1404104)the National Natural Science Foundation of China(Grant Nos.12025509 and 12104521)Fundamental Research Project of Shenzhen(Grant No.JCYJ20230808105009018).
文摘Magneto-optical traps (MOTs) composed of magnetic fields and light fields have been widely utilized to cool andconfine microscopic particles. Practical technology applications require miniaturized MOTs. The advancement of planaroptics has promoted the development of compact MOTs. In this article, we review the development of compact MOTs basedon planar optics. First, we introduce the standardMOTs. We then introduce the gratingMOTs with micron structures, whichhave been used to build cold atomic clocks, cold atomic interferometers, and ultra-cold sources. Further, we introducethe integrated MOTs based on nano-scale metasurfaces. These new compact MOTs greatly reduce volume and powerconsumption, and provide new opportunities for fundamental research and practical applications.
基金Supported by the Key-Area Research and Development Program of Guangdong Province,China (Grant No. 2019B030330001)the National Natural Science Foundation of China (Grant Nos. 12025509 and 11874434)+2 种基金the Science and Technology Program of Guangzhou,China (Grant Nos. 201904020024 and 201804010497)the Natural Science Foundation of Guangdong Province,China(Grant No. 2018A030313988)the Fundamental Research Funds for the Central Universities (Grant No. 2021qntd28)
文摘We report the production of ^(87)Rb Bose–Einstein condensate in an asymmetric crossed optical dipole trap(ACODT)without the need of an additional dimple laser.In our experiment,the ACODT is formed by two laser beams with different radii to achieve efficient capture and rapid evaporation of laser cooled atoms.Compared to the cooling procedure in a magnetic trap,the atoms are firstly laser cooled and then directly loaded into an ACODT without the pre-evaporative cooling process.In order to determine the optimal parameters for evaporation cooling,we optimize the power ratio of the two beams and the evaporation time to maximize the final atom number left in the ACODT.By loading about 6×10^(5) laser cooled atoms in the ACODT,we obtain a pure Bose–Einstein condensate with about 1.4×10^(4) atoms after 19 s evaporation.Additionally,we demonstrate that the fringe-type noises in optical density distributions can be reduced via principal component analysis,which correspondingly improves the reliability of temperature measurement.
基金Project supported by the Key-Area Research and Development Program of GuangDong Province,China (Grant No. 2019B030330001)the National Natural Science Foundation of China (Grant Nos. 12025509, 11874434, and 11704420)+1 种基金the Science and Technology Program of Guangzhou (China)(Grant No. 201904020024)partially supported by the Guangzhou Science and Technology Projects (Grant No. 202002030459)
文摘The open quantum system can be described by either a Lindblad master equation or a non-Hermitian Hamiltonian(NHH).However,these two descriptions usually have different exceptional points(EPs),associated with the degeneracies in the open quantum system.Here,considering a dissipative quantum Rabi model,we study the spectral features of EPs in these two descriptions and explore their connections.We find that,although the EPs in these two descriptions are usually different,the EPs of NHH will be consistent with the EPs of master equation in the weak coupling regime.Further,we find that the quantum Fisher information(QFI),which measures the statistical distance between quantum states,can be used as a signature for the appearance of EPs.Our study may give a theoretical guidance for exploring the properties of EPs in open quantum systems.
基金Project supported by the Key-Area Research and Development Program of Guangdong Province,China(Grant No.2019B030330001)the National Natural ScienceFoundation of China(Grant Nos.12025509 and 11904418)+1 种基金the Science and Technology Program of Guangzhou,China(Grant No.201904020024)the Fundamental Research Funds for the Central Universities,China.
文摘Based upon the new designed helical resonator,the resonant radio frequency(RF)for trapping ions can be consec-utively adjusted in a large range(about 12 MHz to 29 MHz)with high Q-factors(above 300).We analyze the helical resonator with a lumped element circuit model and find that the theoretical results fit well with the experimental data.With our resonator system,the resonant frequency near magic RF frequency(where the scalar Stark shift and the second-order Doppler shift due to excess micromotion cancel each other)can be continuously changed at kHz level.For ^(88)Sr^(+) ion,compared to earlier results,the measurement accuracy of magic RF frequency can be improved by an order of magnitude upon rough calculation,and therefore the net micromotion frequency shifts can be further reduced.Also,the differential static scalar polarizability △α0 of clock transition can be experimentally measured more accurately.
基金Project supported by the Key-Area Research and Development Program of Guang Dong Province,China(Grant No.2019B030330001)the National Natural Science Foundation of China(Grant Nos.11874434 and 11574405)+1 种基金the Science and Technology Program of Guangzhou,China(Grant No.201904020024)the Guangzhou Science and Technology Projects(Grant No.202002030459)。
文摘We present a cluster mean-field study for ground-state phase diagram and many-body dynamics of spin-1 bosons confined in a two-chain Bose-Hubbard ladder(BHL).For unbiased BHL,we find superfluid(SF)phase and integer filling Mott insulator(Int MI)phase.For biased BHL,in addition to the SF and Int MI phases,there appears half-integer filling Mott insulator(HInt MI)phase.The phase transition between the SF and Int MI phases can be first order at a part of phase boundaries,while the phase transition between the SF and HInt MI phases is always second order.By tuning the bias energy,we report on the change of the nature of SF-MI phase transitions.Furthermore,we study the effect of the spin-dependent interaction on the many-body population dynamics.The spin-dependent interaction can lead to rich dynamical behaviors,but does not influence the particle transfer efficiency.Our results indicate a way to tune the nature of the SF-MI phase transition and open a new avenue to study the many-body dynamics of spinor bosons in optical lattices.
