No Arabic abstract
We present measurements of the hyperfine coefficients and isotope shifts of the Dy I $683.731 $nm transition, using saturated absorption spectroscopy on an atomic beam. A King Plot is drawn resulting in an updated value for the specific mass shift $delta u_mathrm{684,sms}^mathrm{164-162}=-534 pm 17 MHz$. Using fluorescence spectroscopy we measure the excited state lifetime $tau_{684}=1.68(5) mu$s, yielding a linewidth of $gamma_mathrm{684} = 95 pm 3 kHz$. We give an upper limit to the branching ratio between the two decay channels from the excited state showing that this transition is useable for optical pumping into a dark state and demagnetization cooling.
We present our technique to create a magneto-optical trap for dysprosium atoms using the narrow-line cooling transition at 626$,$nm to achieve suitable conditions for direct loading into an optical dipole trap. The magneto-optical trap is loaded from an atomic beam via a Zeeman slower using the strongest atomic transition at 421$,$nm. With this combination of two cooling transitions we can trap up to $2.0cdot10^8$ atoms at temperatures down to 6$, mu$K. This cooling approach is simpler than present work with ultracold dysprosium and provides similar starting conditions for a transfer to an optical dipole trap.
A steady-state magneto-optical trap (MOT) of fermionic strontium atoms operating on the 7.5 kHz-wide ${^1mathrm{S}_0} - {^3mathrm{P}_1}$ transition is demonstrated. This MOT features $8.4 times 10^{7}$ atoms, a loading rate of $1.3times 10^{7}$atoms/s, and an average temperature of 12 $mu$K. These parameters make it well suited to serve as a source of atoms for continuous-wave superradiant lasers operating on strontiums mHz-wide clock transition. Such lasers have only been demonstrated using pulsed Sr sources, limiting their range of applications. Our MOT makes an important step toward continuous operation of these devices, paving the way for continuous-wave active optical clocks.
The dispersed fluorescence following pulsed dye laser excitation of the $textrm{B}_2 Sigma^+ - textrm{X}^2 Sigma^+(0,0)$ band of a cold sample of SiO$^+$ has been recorded and analyzed. The branching ratios for $textrm{B}_2 Sigma^+ (v=0) rightarrow textrm{X}^2 Sigma^+(v)$ and $textrm{B}_2 Sigma^+ (v=0) rightarrow textrm{A}^2 Pi_i(v)$ emission were determined and compared with values predicted based upon existing experimental and theoretical data. The experimentally determined branching ratios show that the $textrm{B}_2 Sigma^+ (v=0) rightarrow textrm{X}^2 Sigma^+(v)$ transitions are somewhat less diagonal than predicted. The implications for laser cooling of a trapped sample of SiO$^+$ using broadband laser excitation are discussed.
We report on the experimental realization of a robust and efficient magneto-optical trap for erbium atoms, based on a narrow cooling transition at 583nm. We observe up to $N=2 times 10^{8}$ atoms at a temperature of about $T=15 mu K$. This simple scheme provides better starting conditions for direct loading of dipole traps as compared to approaches based on the strong cooling transition alone, or on a combination of a strong and a narrow kHz transition. Our results on Er point to a general, simple and efficient approach to laser cool samples of other lanthanide atoms (Ho, Dy, and Tm) for the production of quantum-degenerate samples.
Using new experimental measurements of photoassociation resonances near the $^1mathrm{S}_0 rightarrow phantom{ }^3mathrm{P}_1$ intercombination transition in $^{84}$Sr and $^{86}$Sr, we present an updated study into the mass-scaling behavior of bosonic strontium dimers. A previous mass-scaling model [Borkowski et al., Phys. Rev. A 90, 032713 (2014)] was able to incorporate a large number of photoassociation resonances for $^{88}$Sr, but at the time only a handful of resonances close to the dissociation limit were known for $^{84}$Sr and $^{86}$Sr. In this work, we perform a more thorough measurement of $^{84}$Sr and $^{86}$Sr bound states, identifying multiple new resonances at deeper binding energies out to $E/h=-5$ GHz. We also identify several previously measured resonances that cannot be experimentally reproduced and provide alternative binding energies instead. With this improved spectrum, we develop a mass-scaled model that reproduces the observed binding energies of $^{86}$Sr and $^{88}$Sr to within 1 MHz. In order to accurately reproduce the deeper bound states, our model includes a second $1_u$ channel and more faithfully reproduces the depth of the potential. As determined by the previous mass-scaling study, $^{84}$Sr $0_u^+$ levels are strongly perturbed by the avoided crossing between the $^1mathrm{S}_0 + phantom{ }^3mathrm{P}_1$ $0_u^+$ $(^3Pi_u)$ and $^1mathrm{S}_0 + phantom{ }^1mathrm{D}_2$ $0_u^+$ $(^1Sigma_u^+)$ potential curves and therefore are not included in this mass-scaled model, but are accurately reproduced using an isotope-specific model with slightly different quantum defect parameters. In addition, the optical lengths of the $^{84}$Sr $0_u^+, u=-2$ to $ u=-5$ states are measured and compared to numerical estimates to characterize their use as optical Feshbach resonances.