Identification of Deeply Bound Heteronuclear Molecules Using Pulsed Laser Depletion Spectroscopy

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 transfe…

Photoassociative creation of ultracold heteronuclear 6Li40K* molecules

We investigate the formation of weakly bound, electronically excited, heteronuclear 6Li40K* molecules by single-photon photoassociation in a magneto-optical trap. We performed trap loss spectroscopy within a range of 325 GHz below the Li(2S_(1/2))+K(4P_(3/2)) and Li(2S_(1/2))+K(4P_(1/2)) asymptotic states and observed more than 60 resonances, which we identify as rovibrational levels of 7 of 8 attractive long-range molecular potentials. The long-range dispersion coefficients and rotational constants are derived. We find large molecule formation rates of up to ~3.5x10^7s^(-1), which are shown t…

Giant formation rates of ultracold molecules via Feshbach Optimized Photoassociation

Ultracold molecules offer a broad variety of applications, ranging from metrology to quantum computing. However, forming "real" ultracold molecules, {\it i.e.} in deeply bound levels, is a very difficult proposition. Here, we show how photoassociation in the vicinity of a Feshbach resonance enhance molecular formation rates by several orders of magnitude. We illustrate this effect in heteronuclear systems, and find giant rate coefficients even in deeply bound levels. We also give a simple analytical expression for the photoassociation rates, and discuss future applications of the Feshbach Opti…

Stimulating the production of deeply bound RbCs molecules with laser pulses: the role of spin-orbit coupling in forming ultracold molecules

We investigate the possibility of forming deeply bound ultracold RbCs molecules by a two-color photoassociation experiment. We compare the results with those for Rb_2 in order to understand the characteristic differences between heteronuclear and homonuclear molecules. The major differences arise from the different long-range potential for excited states. Ultracold 85Rb and 133Cs atoms colliding on the X^1Sigma+ potential curve are initially photoassociated to form excited RbCs molecules in the region below the Rb(5S) + Cs(6P_1/2) asymptote. We explore the nature of the Omega=0^+ levels in thi…

Production of rovibronic ground state RbCs molecules via two-photon cascade decay

We report the production of ultracold RbCs molecules in the rovibronic ground state, i.e., $X^1Σ^+ (v=0, J=0)$, by short-range photoassociation to the $2^3Π_{0}$ state followed by spontaneous emission. We use narrowband depletion spectroscopy to probe the distribution of rotational levels formed in the $X ^1Σ^+(v=0)$ state. We conclude, based on selection rules, that the primary decay route to $X ^1Σ^+(v=0)$ is a two-step cascade decay that leads to as much as $33\%$ branching into the $J=0$ rotational level. The experimental simplicity of our scheme opens up the possibility of easier access t…

超冷碱土金属双原子分子的化学反应

Chemical reactions of ultracold alkaline-earth-metal diatomic molecules

本文通过电子结构计算研究超冷碱土金属双原子分子的反应能量学，发现原子交换和三聚体形成均无势垒、能量允许，表明这些分子在超低温下化学不稳定，需光晶格或屏蔽方案抑制损耗。