The hyperfine structure of the 13Δg state of Na 2

The hyperfine Hamiltonian for a homonuclear diatomic molecule was expressed in the Hund's case b βS basis. With this matrix, the hyperfine splittings for the Na 2 1 3Δ g state were theoretically calculated. The hyperfine spectra of Na 2 1 3Δ g ← b 3π 1u transitions for both high- and low-rotational quantum numbers were reanalyzed. Overall, significant results were obtained.published_or_final_versio

Creation of ultracold molecules from a Fermi gas of atoms

Since the realization of Bose-Einstein condensates (BEC) in atomic gases an experimental challenge has been the production of molecular gases in the quantum regime. A promising approach is to create the molecular gas directly from an ultracold atomic gas; for example, atoms in a BEC have been coupled to electronic ground-state molecules through photoassociation as well as through a magnetic-field Feshbach resonance. The availability of atomic Fermi gases provides the exciting prospect of coupling fermionic atoms to bosonic molecules, and thus altering the quantum statistics of the system. This Fermi-Bose coupling is closely related to the pairing mechanism for a novel fermionic superfluid proposed to occur near a Feshbach resonance. Here we report the creation and quantitative characterization of exotic, ultracold $^{40}$K$_2$ molecules. Starting with a quantum degenerate Fermi gas of atoms at T < 150 nanoKelvin we scan over a Feshbach resonance to adiabatically create over a quarter million trapped molecules, which we can convert back to atoms by reversing the scan. The small binding energy of the molecules is controlled by detuning from the Feshbach resonance and can be varied over a wide range. We directly detect these weakly bound molecules through rf photodissociation spectra that probe the molecular wavefunction and yield binding energies that are consistent with theory

Ultracold dense gas of deeply bound heteronuclear molecules

Recently, the quest for an ultracold and dense ensemble of polar molecules has attracted strong interest. Polar molecules have bright prospects for novel quantum gases with long-range and anisotropic interactions, for quantum information science, and for precision measurements. However, high-density clouds of ultracold polar molecules have so far not been produced. Here, we report a key step towards this goal. Starting from an ultracold dense gas of heteronuclear 40K-87Rb Feshbach molecules with typical binding energies of a few hundred kHz and a negligible dipole moment, we coherently transfer these molecules into a vibrational level of the ground-state molecular potential bound by >10 GHz. We thereby increase the binding energy and the expected dipole moment of the 40K-87Rb molecules by more than four orders of magnitude in a single transfer step. Starting with a single initial state prepared with Feshbach association, we achieve a transfer efficiency of 84%. While dipolar effects are not yet observable, the presented technique can be extended to access much more deeply bound vibrational levels and ultimately those exhibiting a significant dipole moment. The preparation of an ultracold quantum gas of polar molecules might therefore come within experimental reach.Comment: 5 pages, 5 figure

PERTURBATION-FACILITATED ALL-OPTICAL TRIPLE RESONANCE SPECTROSCOPY OF THE NA2 B 3-PI-U STATE

The Na2 b 3PI(u) state has been studied by the continuous wave (cw) all-optical triple resonance (AOTR) technique. The AOTR technique used here corresponds to a perturbation-facilitated optical-optical double resonance (PFOODR) excitation through A 1SIGMA(u)+ approximately b 3PI(u) mixed intermediate levels from the ground state to the 2 3PI(g) state and stimulated emission pumping (SEP) of the 2 3PI(g) --> 3PI(u) transition. This sub-Doppler high-resolution PFOODR-SEP technique has allowed us to reach many b 3PI(u) levels (OMEGA=0, 1, 2, perturbed and unperturbed, including low v below the A1 SIGMA(u)+ potential minimum and higher vibrational levels up to v = 57). Based on these new high resolution data and previous results from high resolution spectroscopy, we have determined a new set of deperturbed molecular constants from the b 3PI(u) state up to nu=57, the corresponding RKR potential energy curve and the A 1SIGMA(u)+ approximately 3PI(u) spin-orbit interaction constants. This represents an example of a powerful and general technique for observing a "dark" (e.g., triplet) perturbing state when only the "bright" (e.g., singlet) perturbed state is well known from single photon spectroscopy

CW ALL-OPTICAL TRIPLE RESONANCE SPECTROSCOPY

This paper reports for the first time continuous-wave, high-resolution, all-optical triple resonance spectroscopy. Using this technique, one can overcome the spin forbidden nature of a singlet-triplet transition and consequently unperturbed triplet rovibronic levels can be reached from a singlet ground state. This technique also facilitates state-selective population transfer to highly excited vibrational levels, both in the ground state and in excited states