We report on the photoassociation (PA) spectroscopy of cold
171Yb atoms in a one-dimensional optical lattice. The PA spectral lines correlating to the
1S0+3P1 (f=1/2) state are observed experimentally. High accuracy and narrow atom-loss spectra are measured ranging up to about 1.2 GHz red detuning with respect to the atomic resonance. The main systematic frequency shifts of the PA transitions are determined with total uncertainties less than 100 kHz, which is more accurate than previous similar experimental results. We determine the initial scattering state of the PA spectra by comparing the spectra with polarized and unpolarized atomic samples. By comparatively analyzing theoretical results calculated based on an adiabatic molecular potential with experimental data, the excited molecular potentials corresponding to the spectral lines are clarified. The precision measurement of the narrow PA spectra plays an important role in exploring atomic interactions and lays the groundwork for the study of cold ytterbium molecules.
in a lattice. Sr2 has a range of electronically excited bound states which are readily accessible with optical wavelengths using the narrow 1S0->3P1 intercombination line. As in Nat. Phys. 11, 32, we measure the lifetimes of the narrow, deeply-bound subradiant states in the 1g (1S0+3P1 dissociative limit) potential, allowing for coherent control of molecules and a comparison with theoretical predictions of the lifetimes and transition strengths of these states. Next, we study ultracold photodissociation of Sr2 molecules through abortion of one and two photons near the atomic intercombination line. This allows us to observe the vector character of transition elements through the angular dissociation pattern and to directly measure barrier heights in the excited state potentials. Finally, as shown in PRL 114, 023001, we demonstrate that in a non-magic lattice, a narrow transition can be used to measure the trapped gas temperature through the linewidth of the spectral feature corresponding to the carrier transitions. We use this technique to measure the temperature of Sr2 molecules to 10x higher precision than with standard techniques. We discuss future prospects with this molecular lattice clock. 1 Funding from NIST, ARO, and NSF IGERT
We observed high-resolution photoassociation spectra of laser-cooled ytterbium (Yb) atoms in the spin-forbidden 1S0 - 3P1 intercombination line. The rovibrational levels in the 0u+ state were measured for red detunings of the photoassociation laser ranging from 2.9 MHz to 1.97 GHz with respect to the atomic resonance. The rotational splitting of the vibrational levels near the dissociation limit were fully resolved due to the sub-MHz linewidth of the spectra in contrast to previous measurements using the spin-allowed singlet transition. In addition, from a comparison between the spectra of 174Yb and those of 176Yb, a d-wave shape resonance for 174Yb is strongly suggested.
Photoassociation (PA) of cold atoms is a key tool widely used for accurate determination of long-range molecular potentials, measurement and tuning of interatomic interactions, as well as creation of desired cold molecules. We report the observation of PA spectra of ultracold ytterbium (Yb) atoms at the 1 S 0 — 3 P 1 inter-combination line by detecting the resonant loss of atoms trapped in a crossed far-off-resonance trap (crossed-FORT). Eight vibrational levels in the 1 0 + u molecular state are observed for PA laser detunings up to 1 GHz with respect to the atomic resonance. The photoassociation resonances have a Lorentzian shape and sub-MHz linewidths due to the ultra low temperature of the atoms, and the resonance positions agree well with that predicted by the semiclassical formula.
State-of-the-art ab initio techniques have been applied to compute the potential energy curves for the SrYb molecule in the Born-Oppenheimer approximation for the electronic ground state and the first fifteen excited singlet and triplet states. All the excited state potential energy curves were computed using the equation of motion approach within the coupled-cluster singles and doubles framework and large basis-sets, while the ground state potential was computed using the coupled cluster method with single, double, and noniterative triple excitations. The leading long-range coefficients describing the dispersion interactions at large interatomic distances are also reported. The electric transition dipole moments have been obtained as the first residue of the polarization propagator computed with the linear response coupled-cluster method restricted to single and double excitations. Spin-orbit coupling matrix elements have been evaluated using the multireference configuration interaction method restricted to single and double excitations with a large active space. The electronic structure data were employed to investigate the possibility of forming deeply bound ultracold SrYb molecules in an optical lattice in a photoassociation experiment using continuous-wave lasers. Photoassociation near the intercombination line transition of atomic strontium into the vibrational levels of the strongly spin-orbit mixed b(3)Σ(+), a(3)Π, A(1)Π, and C(1)Π states with subsequent efficient stabilization into the v'' = 1 vibrational level of the electronic ground state is proposed. Ground state SrYb molecules can be accumulated by making use of collisional decay from v'' = 1 to v'' = 0. Alternatively, photoassociation and stabilization to v'' = 0 can proceed via stimulated Raman adiabatic passage provided that the trapping frequency of the optical lattice is large enough and phase coherence between the pulses can be maintained over at least tens of microseconds.
We predict feasibility of the photoassociative formation of Sr
2 molecules in arbitrary vibrational levels of the electronic ground state based on state-of-the-art ab initio calculations. Key is the strong spin-orbit interaction between the
c${}^{3}\phantom{\rule{-0.16em}{0ex}}{\ensuremath{\Pi}}_{u}$,
A${}^{1}\phantom{\rule{-0.16em}{0ex}}{\ensuremath{\Sigma}}_{u}^{+}$, and
B${}^{1}\phantom{\rule{-0.16em}{0ex}}{\ensuremath{\Sigma}}_{u}^{+}$ states. It creates not only an effective dipole moment allowing free-to-bound transitions near the
1S+3P1 intercombination line but also facilitates bound-to-bound transitions via resonantly coupled excited-state levels to deeply bound levels of the ground
X${}^{1}\phantom{\rule{-0.16em}{0ex}}{\ensuremath{\Sigma}}_{g}^{+}$ potential, with ${v}^{\ensuremath{'}\ensuremath{'}}$ as low as ${v}^{\ensuremath{'}\ensuremath{'}}=6$. The spin-orbit interaction is responsible for both optical pathways. Therefore, those excited-state levels that have the largest bound-to-bound transition moments to deeply bound ground-state levels also exhibit a sufficient photoassociation probability, comparable to that of the lowest weakly bound excited-state level previously observed by Zelevinsky et al. [Phys. Rev. Lett. 96, 203201 (2006)]. Our study paves the way for an efficient photoassociative production of Sr
2 molecules in ground-state levels suitable for experiments testing the electron-to-proton mass ratio.