We present a faster repumping scheme for strontium magneto-optical traps operating on the broad 5 s 2 1 S 0 − 5 s 5 p 1 P 1 laser cooling transition. Contrary to existing repumping schemes, we directly address lost atoms that spontaneously decayed to the 5 s 4 d 1 D 2 state, sending them back into the laser cooling cycle by optical pumping on the 5 s 4 d 1 D 2 − 5 s 8 p 1 P 1 transition. We thus avoid the ∼ 100 µ s -slow decay path from 5 s 4 d 1 D 2 to the 5 s 5 p 3 P 1 , 2 states that is part of other repumping schemes. Using one low-cost external-cavity diode laser emitting at 448 nm , we show our scheme increases the flux out of a 2D magneto-optical trap by 60 % compared to without repumping. Furthermore, we perform spectroscopy on the 5 s 4 d 1 D 2 − 5 s 8 p 1 P 1 transition and measure its frequency ν Sr 88 = ( 668917515.3 ± 4.0 ± 25 ) MHz . We also measure the frequency shifts between the four stable isotopes of strontium and infer the specific mass and field shift factors, δ ν SMS 88 , 86 =<
We present a faster repumping scheme for strontium magneto-optical traps operating on the broad
5s21S0−5s5p1P1 laser cooling transition. Contrary to existing repumping schemes, we directly address lost atoms that spontaneously decayed to the
5s4d1D2 state, sending them back into the laser cooling cycle by optical pumping on the
5s4d1D2−5s8p1P1 transition. We thus avoid the
∼100μs-slow decay path from
5s4d1D2 to the
5s5p3P1,2 states that is part of other repumping schemes. Using one low-cost external-cavity diode laser emitting at
448nm, we show our scheme increases the flux out of a 2D magneto-optical trap by
60% compared to without repumping. Furthermore, we perform spectroscopy on the
5s4d1D2−5s8p1P1 transition and measure its frequency
ν88Sr=(668917515.3±4.0±25)MHz. We also measure the frequency shifts between the four stable isotopes of strontium and infer the specific mass and field shift factors,
δνSMS88,86=−267(45)MHz and
δνFS88,86=2(42)MHz. Finally, we measure the hyperfine splitting of the
5s8p1P1 state in fermionic strontium, and deduce the magnetic dipole and electric quadrupole coupling coefficients
A=−4(5)MHz and
B=5(35)MHz. Our experimental demonstration shows that this simple and very fast scheme could improve the laser cooling and imaging performance of cold strontium atom devices, such as quantum computers based on strontium atoms in arrays of optical tweezers.
We have demonstrated Zeeman slowing and capture of neutral 225Ra and 226Ra atoms in a magneto-optical trap. The intercombination transition 1S0-->3P1 is the only quasicycling transition in radium and was used for laser-cooling and trapping. Repumping along the 3D1-->1P1 transition extended the lifetime of the trap from milliseconds to seconds. Room-temperature blackbody radiation was demonstrated to provide repumping from the metastable 3P0 level. We measured the isotope shift and hyperfine splittings on the 3D1-->1P1 transition with the laser-cooled atoms, and set a limit on the lifetime of the 3D1 level based on the measured blackbody repumping rate. Laser-cooled and trapped radium is an attractive system for studying fundamental symmetries.