Transfer of Bose–Einstein Condensates from Quadrupole-Ioffe-configuration Magnetic Trap to Crossed-beam Optical Trap

Abstract

We studied the transfer of ⁸⁷Rb Bose–Einstein condensates prepared in a quadrupole-Ioffe-configuration (QUIC) magnetic trap to a far-detuned crossed-beam optical trap. The condensates could not be effectively transferred by merely switching the QUIC trap off after superposing the optical trap beams onto magnetically trapped condensates. This was attributed to the transient magnetic field generated by eddy currents, which were induced by the switching-off of the QUIC trap. We suppressed this transient field by applying a magnetic pulse field that was synchronized with the switching-off of the QUIC trap, thereby achieving the efficient transfer of condensates to the optical trap. The transfer rate was estimated to be approximately 70%, and the 1/e lifetime of the optical trap was measured to be 3.1 ± 0.2 s.