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 describe repumping and spectroscopy of laser-cooled strontium (Sr) atoms using the (5s5p) 3 P 2 –(5s4d) 3 D 2 transition. Atom number in a magneto-optical trap is enhanced by driving this transition because Sr atoms that have decayed into the (5s5p) 3 P 2 dark state are repumped back into the (5s 2 ) 1 S 0 ground state. Spectroscopy of 84 Sr, 86 Sr, 87 Sr and 88 Sr improves the value of the (5s5p) 3 P 2 –(5s4d) 3 D 2 transition frequency and determines the isotope shifts for the transition accurately enough to guide laser-cooling experiments with less abundant isotopes.
Abstract This article presents spectroscopy results of the 5 s 5 p 3 P 0 → 5 s 5 d 3 D 1 transition in all isotopes of laser cooled Sr atoms and the utility of this transition for repumping application. By employing the 5 s 5 p 3 P 0 → 5 s 5 d 3 D 1 (483 nm) transition in combination with the excitation of 5 s 5 p 3 P 2 → 5 s 6 s 3 S 1 (707 nm) transition, we observe a significant increase (∼13 fold) in the steady state number of atoms in the magneto-optic trap. This enhancement is attributed to the efficient repumping of Sr atoms that have decayed into the dark 5 s 5 p 3 P 2 state by returning them to the ground state 5 s 2 1 S 0 without any loss into the other states. The absolute transition frequencies were measured with an absolute accuracy of 30 MHz. To support our measurements, we performed Fock-space relativistic coupled-cluster calculations of the relevant parameters in Sr To further increase the accuracy of the calculated properties, corrections from the Breit, quantum electrodynamical and perturbative triples were also included. The calculated branching ratio for the repumping state confirms the significantly increased population in the 3 P 1 state. Thereby, leading to an increase of population of atoms trapped due to the enhanced repumping. Our calculated hyperfine-splitting energies are in excellent agreement with the measured values. Moreover, our calculated isotope shifts in the transition frequencies are in good agreement with our measured values.
This article presents spectroscopy results of the
5s5p3P0→5s5d3D1 transition in all isotopes of laser cooled Sr atoms and the utility of this transition for repumping application. By employing the $5s5p{\;^{3} P_{0}} \rightarrow 5s5d{\;^3}D_1 $ (483 nm) transition in combination with the excitation of
5s5p3P2→5s6s3S1 (707 nm) transition, we observe a significant increase (
∼ 13 fold) in the steady state number of atoms in the magneto-optic trap (MOT). This enhancement is attributed to the efficient repumping of Sr atoms that have decayed into the dark
5s5p3P2 state by returning them to the ground state
5s21S0 without any loss into the other states. The absolute transition frequencies were measured with an absolute accuracy of 30 MHz. To support our measurements, we performed Fock-space relativistic coupled-cluster calculations of the relevant parameters in Sr. To further increase the accuracy of the calculated properties, corrections from the Breit, QED and perturbative triples were also included. The calculated branching ratio for the repumping state confirms the significantly increased population in the
3P1 state. Thereby, leading to an increase of population of atoms trapped due to the enhanced repumping. Our calculated hyperfine-splitting energies are in excellent agreement with the measured values. Moreover, our calculated isotope shifts in the transition frequencies are in good agreement with our measured values.
We explore the efficacy of two single-repumping schemes, 5 s 5 p P 2 3 − 5 p 2 P 2 3 ( 481 nm ) and 5 s 5 p P 2 3 − 5 s 5 d D 2 3 ( 497 nm ) , for a magneto-optical trap (MOT) of Sr atoms. We reveal that the enhancement in the MOT lifetime is limited to 26.9(2) for any single-repumping scheme. Our investigation indicates that the primary decay path from the 5 s 5 p P 1 1 state to the 5 s 5 p P 0 3 state proceeds via the 5 s 4 d D 1 3 state, rather than through the upper states accessed by the single-repumping lasers. We estimate that the branching ratio for the 5 s 5 p P 1 1 → 5 s 4 d D 1 3 → 5 s 5 p P 0 3 decay path is 1 : 3.9 ( 1.5 ) × 10 6 and the decay rate for the transition from the 5 s 5 p P 1 1 state to the 5 s 4 d
We investigate a repumping scheme for magneto-optically trapped calcium atoms. It is based on excitation of the
4s3d1D2--
4s5p1P1 transition at
672 nm with an extended cavity diode laser. The effect of the repumping is approximately a factor of three increase in trap lifetime and a doubling of the trapping efficiency from a Zeeman slowed thermal beam. Added to this, the 672-nm laser repumps atoms from an otherwise dark state to yield an overall increase in detected fluorescence signal from the magneto-optic trap (MOT) of more than an order of magnitude. Furthermore, we report isotope shift measurements of the
672-nm transition, for the first time, for four naturally occurring even isotopes. Using available charge radii data, the observed shifts, extending up to
4.3 GHz, display the expected linear dependence in a King plot analysis. The measured shifts are used to determine the isotope shifts of the remaining
41,43,46Ca isotopes. These might be of interest where less abundant isotopes are used enabling isotope selective repumping, resulting in enhanced trapping and detection efficiencies.