Reservoir spectroscopy of5s5p3P2–5sn

Abstract

We perform spectroscopy on the optical dipole transitions 5s5p 3 P 2 -5snd 3 D 1,2,3 , n ∈ (5,6), for all stable isotopes of atomic strontium. We develop a spectroscopy scheme in which atoms in the metastable 3 P 2 state are stored in a reservoir before being probed. The method presented here increases the attained precision and accuracy by two orders of magnitude compared to similar experiments performed in a magneto-optical trap or discharge. We show how the state distribution and velocity spread of atoms in the reservoir can be tailored to increase the spectroscopy performance. The absolute transition frequencies are measured with an accuracy of 5 MHz. The isotope shifts are given to within 200 kHz. We calculate the A and Q parameters for the hyperfine structure of the fermionic isotope at the MHz level. Furthermore, we investigate the branching ratios of the 3 D J states into the 3 P J states and discuss immediate implications on schemes of optical pumping and fluorescence detection.

Two-dimensional magneto-optical trap as a source for cold strontium atoms

“…However, applying repumping light can play an important role in prolonging the lifetime of a 3D-MOT (see Sec. IV) or by recollecting atoms in the reservoir state magnetically trapped by the MOT field [34,41]. Accordingly, we use a repumping laser (Toptica, DL 100) to address the transition 5s5p 3 P 2 → 5p 2 3 P 2 at 481 nm to increase the lifetime of the 3D-MOT [41,42].…”

Comparison between 403 nm and 497 nm repumping schemes for strontium magneto-optical traps

“…We represent this loading by a vector  ( ) b t , whose components are all zero except for the one at the same position of the population ρ 1 transition being a popular choice [20]. Stellmer et al [19] recently proposed to use the ñ  º ñ…”

“…The measurements described in the next section compare both schemes. It is important to note that both upper levels ñ |7 g and ñ |7 b present different decay probabilities to the metastable º ñ ( ) | 5s5p P 4 3 0 level by indirect dipole-allowed decay paths through several intermediate levels [19]. For 88 Sr, the lifetime of the level is calculated to be thousands of years [28]; magnetic fields can shorten it to a fraction of a second [29].…”

“…Most of them are direct natural decay rates, reported in the literature (the references are given in the table caption). For the G k g 7 and G k b 7 decay rates, with k=5, 6 (see figure 1), we have computed a total decay rate, considering the direct decay path and the indirect ones through dipole-allowed transitions, calculated following the lines of [19]. For the G g 47 and G b 47 decay rates, the above calculation gives p G =2…”

“…In this paper, simplified names are given for the relevant levels, such as ñ |1 or ñ |7 g , as explained in the main text. Note that the decay rate Γ 24 is not reported in the literature, but we have included following a hypothesis raised by Stellmer et al, [19], discussed in the main text. See also table 1.…”