This work experimentally demonstrates a new method of optimizing the transport of cold atoms via modulating the velocity profile imposed on a magnetic quadrupole trap.The trap velocity and corresponding modulation are...This work experimentally demonstrates a new method of optimizing the transport of cold atoms via modulating the velocity profile imposed on a magnetic quadrupole trap.The trap velocity and corresponding modulation are controlled by varying the currents of two pairs of anti-Helmholtz coils.Cold 87Rb atoms are transported in a non-adiabatic regime over 22 mm in 200 ms.For the transported atoms their final-vibration amplitude dependences of modulation period number,depth,and initial phase are investigated.With modulation period n = 5,modulation depth K = 0.55,and initial phase φ = 0,cold atom clouds with more atom numbers,smaller final-vibration amplitude,and lower temperature are efficiently transported.Theoretical analysis and numerical simulation are also provided,which are in good agreement with experimental results.展开更多
We present a scheme for generating a ring magnetic waveguide on a single-layer atom chip. The wire layout consists of two interleaved Archimedean spirals of the same size. The waveguide avoids the trapping perturbatio...We present a scheme for generating a ring magnetic waveguide on a single-layer atom chip. The wire layout consists of two interleaved Archimedean spirals of the same size. The waveguide avoids the trapping perturbation caused by the input and output ports, resulting in an enclosed guiding loop for neutral atoms in weak-field seeking states. Such a configuration can create a tight and deep trap potential with a small current. Taking the [F = 2, mF =2} state of 87Rb as an example, the trap frequency and depth are estimated to be 18kHz and 335 μK, respectively, with adc current of 2 A.展开更多
We demonstrate the direct loading of cold atoms into a microchip 2-mm Z-trap, where the evaporative cooling can be performed efficiently, from a macroscopic quadrupole magnetic trap with a high loading efficiency. The...We demonstrate the direct loading of cold atoms into a microchip 2-mm Z-trap, where the evaporative cooling can be performed efficiently, from a macroscopic quadrupole magnetic trap with a high loading efficiency. The macroscopic quadrupole magnetic trap potential is designed to be moveable by controlling the currents of the two pairs of anti-Helrnholtz coils. The cold atoms are initially prepared in a standard six-beam magneto-optical trap and loaded into the macroscopic quadrupole magnetic trap, and then transported to the atom chip surface by moving the macroscopic trap potential. By means of a three-dimensional absorption imaging system, we are able to optimize the position alignment of the atom cloud in the macroscopic trap and the microchip Z-shaped wire. Consequently, with a proper magnetic transfer scheme, we load the cold atoms into the microchip Z-trap directly and efficiently. The loading efficiency is measured to be about 50%. This approach can be used to generate appropriate ultracold atoms sources, for example, for a magnetically guided atom interferometer based on atom chip.展开更多
It is demonstrated experimentally that the anharmonic property of the quadrupole trap can be exploited to cool trapped atoms by modulating the trap potential anisotropically. This cooling effect arises from the energy...It is demonstrated experimentally that the anharmonic property of the quadrupole trap can be exploited to cool trapped atoms by modulating the trap potential anisotropically. This cooling effect arises from the energy-selective removal of the most energetic trapped atoms and the thermal equilibrium of the remaining atoms. The frequency dependences of the temperature and the fraction of the atoms left in the trap after the modulation are explored. It is also demonstrated that the cooling induced by parametric resonance can also increase the phase space density of the trapped atoms.展开更多
We demonstrate that the parametric resonance in a magnetic quadrupole trap can be exploited to cool atoms by using Bird＇s method. In our programme the parametric resonance was realized by anisotropically modulating t...We demonstrate that the parametric resonance in a magnetic quadrupole trap can be exploited to cool atoms by using Bird＇s method. In our programme the parametric resonance was realized by anisotropically modulating the trap potential. The modulation frequency dependences of temperature and fraction of the trapped atoms are explored. Furthermore, the temperature after the modulation as functions of the modulation amplitude and the mean elastic collision time are also studied. These results are valuable for the experiment of parametric resonance in a quadrupole trap.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant No. 10974210)the National Basic Research Program of China (Grant No. 2011CB921504)
文摘This work experimentally demonstrates a new method of optimizing the transport of cold atoms via modulating the velocity profile imposed on a magnetic quadrupole trap.The trap velocity and corresponding modulation are controlled by varying the currents of two pairs of anti-Helmholtz coils.Cold 87Rb atoms are transported in a non-adiabatic regime over 22 mm in 200 ms.For the transported atoms their final-vibration amplitude dependences of modulation period number,depth,and initial phase are investigated.With modulation period n = 5,modulation depth K = 0.55,and initial phase φ = 0,cold atom clouds with more atom numbers,smaller final-vibration amplitude,and lower temperature are efficiently transported.Theoretical analysis and numerical simulation are also provided,which are in good agreement with experimental results.
基金Supported by the National Basic Research Program of China under Grant No 2001CB309307the National Natural Science Foundation of China under Grant Nos 10974210 and 10474105
文摘We present a scheme for generating a ring magnetic waveguide on a single-layer atom chip. The wire layout consists of two interleaved Archimedean spirals of the same size. The waveguide avoids the trapping perturbation caused by the input and output ports, resulting in an enclosed guiding loop for neutral atoms in weak-field seeking states. Such a configuration can create a tight and deep trap potential with a small current. Taking the [F = 2, mF =2} state of 87Rb as an example, the trap frequency and depth are estimated to be 18kHz and 335 μK, respectively, with adc current of 2 A.
基金Project supported by the National Natural Science Foundation of China(Grant No.11604348)
文摘We demonstrate the direct loading of cold atoms into a microchip 2-mm Z-trap, where the evaporative cooling can be performed efficiently, from a macroscopic quadrupole magnetic trap with a high loading efficiency. The macroscopic quadrupole magnetic trap potential is designed to be moveable by controlling the currents of the two pairs of anti-Helrnholtz coils. The cold atoms are initially prepared in a standard six-beam magneto-optical trap and loaded into the macroscopic quadrupole magnetic trap, and then transported to the atom chip surface by moving the macroscopic trap potential. By means of a three-dimensional absorption imaging system, we are able to optimize the position alignment of the atom cloud in the macroscopic trap and the microchip Z-shaped wire. Consequently, with a proper magnetic transfer scheme, we load the cold atoms into the microchip Z-trap directly and efficiently. The loading efficiency is measured to be about 50%. This approach can be used to generate appropriate ultracold atoms sources, for example, for a magnetically guided atom interferometer based on atom chip.
基金the National Natural Science Foundation of China(No.10474105)the National Basic Research Programme of China(No.2006CB921202)
文摘It is demonstrated experimentally that the anharmonic property of the quadrupole trap can be exploited to cool trapped atoms by modulating the trap potential anisotropically. This cooling effect arises from the energy-selective removal of the most energetic trapped atoms and the thermal equilibrium of the remaining atoms. The frequency dependences of the temperature and the fraction of the atoms left in the trap after the modulation are explored. It is also demonstrated that the cooling induced by parametric resonance can also increase the phase space density of the trapped atoms.
基金Supported by the National Natural Science Foundation of China under Grant No 10474105, and the National Basic Research Programme of China under Grant No 2006CB921202.
文摘We demonstrate that the parametric resonance in a magnetic quadrupole trap can be exploited to cool atoms by using Bird＇s method. In our programme the parametric resonance was realized by anisotropically modulating the trap potential. The modulation frequency dependences of temperature and fraction of the trapped atoms are explored. Furthermore, the temperature after the modulation as functions of the modulation amplitude and the mean elastic collision time are also studied. These results are valuable for the experiment of parametric resonance in a quadrupole trap.
