Production of dual species Bose–Einstein condensates of ^(39)K and ^(87)Rb

We report the production of^(39) K and^(87) Rb Bose–Einstein condensates(BECs) in the lowest hyperfine states |F =1, m_(F) = 1 simultaneously. We collect atoms in bright/dark magneto-optical traps(MOTs) of^(39) K/^(87) Rb to overcome the light-assisted losses of^(39) K atoms. Gray molasses cooling on the D1 line of the^(39) K is used to effectively increase the phase density, which improves the loading efficiency of^(39) K into the quadrupole magnetic trap. Simultaneously, the normal molasses is employed for^(87) Rb. After the microwave evaporation cooling on^(87) Rb in the optically plugged magnetic trap,the atoms mixture is transferred to a crossed optical dipole trap, where the collisional properties of the two species in different combinations of the hyperfine states are studied. The dual species BECs of^(39) K and^(87) Rb are obtained by further evaporative cooling in an optical dipole trap at a magnetic field of 372.6 G with the background repulsive interspecies scattering length a_(KRb)= 34 a_(0)(a_(0) is the Bohr radius) and the intraspecies scattering length a_K= 20.05 a_(0).

Influence on the Lifetime of ^(87)Rb Bose-Einstein Condensation for Far-Detuning Single-Frequency Lasers with Different Phase Noises

We study the influence of the phase noises of far detuning single frequency lasers on the lifetime of Bose-Einstein condensation（BEC）of^（87）Rb in an optical dipole trap.As a comparison,we shine a continuous-wave singlefrequency Ti：sapphire laser,an external-cavity diode laser and a phase-locked diode laser on BEC.We measure the heating and lifetime of BEC in two different hyperfine states：｜F=2,m_F=2〉and｜F=1,m_F=1〉.Due to the narrow linewidth and small phase noise,the continuous-wave single-frequency Ti：sapphire laser has less influence on the lifetime of^（87）Rb BEC than the external-cavity diode laser.To reduce the phase noise of the external-cavity diode laser,we use an optical phase-locked loop for the external-cavity diode laser to be locked on a Ti：sapphire laser.The lifetime of BEC is increased when applfying the phase-Jocked diode laser in contrast with the external-cavity diode laser.