The authors propose the laser cooling scheme for eleven transition-metal atoms, including both bosonic and fermionic species. A number of cycling optical transitions from the ground state or from a long-lived metastable state to the excited states are identified for the cooling scheme.
We report in this talk the first demonstration of the laser cooling of a metastatic atomic bean, and the transfer of cooled atoms between two different metastatic states. The laser cooling and trapping of neutral atoms have been demonstrated only on alkali atoms. It is of great interest to extend this technique to other atomic species. The standard cooling scheme for those atoms uses the ground state as the lower energy level of the cooling transition. The cooling transtion must have a sizable transition moment and its wavelength must be in the region where a continuous laser is available. Such an excited level can generally be found in alkali, alkali earths. For many transition and rare-earth metals, an adequate excited level can be found only in relatively high excited states.
The efficiency of laser cooling relies on the existence of an almost closed optical-transition cycle in the energy spectrum of the considered species. In this respect, rare-earth elements exhibit many transitions which are likely to induce noticeable leaks from the cooling cycle. In this work, to determine whether laser cooling of singly ionized erbium Er+ is feasible, we have performed accurate electronic-structure calculations of energies and spontaneous-emission Einstein coefficients of Er+, using a combination of ab initio and least-squares-fitting techniques. We identify five weak closed transitions suitable for laser cooling, the broadest of which is in the kilohertz range. For the strongest transitions, by simulating the cascade dynamics of spontaneous emission, we show that repumping is necessary, and we discuss possible repumping schemes. We expect our detailed study on Er+ to give good insight into the laser cooling of neighboring ions such as Dy+.
Despite the prominent role of laser cooling in modern atomic physics, with applications ranging from quantum sensors to high-precision spectroscopy and ultracold chemistry, laser cooling techniques are still limited to atoms with simple energy level structure and closed transitions that are accessible by currently available continuous wave (cw) laser sources. Two main obstacles prevent the extension of laser cooling techniques to a variety of atomic species and molecules. The first is associated with technical difficulties in creating cw laser light in the vacuum ultraviolet (VUV) spectral range - the absence of those laser sources prevents laser cooling of simple atoms such as hydrogen, deuterium, and antihydrogen. The second obstacle is associated with complex energy level structure of many atoms and almost all molecules - it permits decay of an excited state into a number of lower-lying states that can be widely separated in energy, which makes laser cooling of such species inefficient and experimentally very challenging.
We propose a scheme to directly laser cool Rydberg atoms by laser cooling the residual ion core within the Rydberg-electron orbit. The scheme is detailed for alkaline-earth-metal Rydberg atoms, whose ions can be easily laser cooled. We demonstrate that a closed optical cooling cycle can be found despite the perturbations caused by the Rydberg electron and that this cycle can be driven over more than 100 μs to achieve laser cooling. The cooling dynamics with and without the presence of magnetic fields are discussed in detail.
We realize a magneto-optical trap (MOT) of titanium (Ti) atoms, performing laser cooling on the 498 nm transition between the long-lived 3 d 3 ( F 4 ) 4 s a 5 F 5 metastable state and the 3 d 3 ( F 4 ) 4 p y 5 G 6 o excited state. Without the addition of any repumping light, we observe MOTs of the three stable, I = 0 bosonic isotopes, Ti 46 , Ti 48 , and Ti 50 . Up to 8.30 ( 26 ) × 10 5 Ti 48 atoms are trapped at a maximum density of 1.3 ( 4 ) × 10 11 cm − 3 and at a temperature of 90 ( 15 ) µ K . By measuring the decay of the MOT, we constrain the leakage branching ratio of the cooling transition ( ≤ 2.5 × 10 − 6 ) and the two-body loss coefficient ( ≤ 2 × 10 − 10 cm 3 s − 1 ). Our approach to laser cooling Ti can be applied to other transition metals, enabling a significant expansion of the elements that can be laser cooled.