Optimal transport of cold atoms by modulating the velocity of traps

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.