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We present the properties of a magneto-optical trap (MOT) of CaF molecules. We study the process of loading the MOT from a decelerated buffer-gas-cooled beam, and how best to slow this molecular beam in order to capture the most molecules. We determine how the number of molecules, the photon scattering rate, the oscillation frequency, damping constant, temperature, cloud size and lifetime depend on the key parameters of the MOT, especially the intensity and detuning of the main cooling laser. We compare our results to analytical and numerical models, to the properties of standard atomic MOTs, and to MOTs of SrF molecules. We load up to $2 times 10^4$ molecules, and measure a maximum scattering rate of $2.5 times 10^6$ s$^{-1}$ per molecule, a maximum oscillation frequency of 100 Hz, a maximum damping constant of 500 s$^{-1}$, and a minimum MOT rms radius of 1.5 mm. A minimum temperature of 730 $mu$K is obtained by ramping down the laser intensity to low values. The lifetime, typically about 100 ms, is consistent with a leak out of the cooling cycle with a branching ratio of about $6 times 10^{-6}$. The MOT has a capture velocity of about 11 m/s.
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We study inelastic collisions between CaF molecules and $^{87}$Rb atoms in a dual-species magneto-optical trap. The presence of atoms increases the loss rate of molecules from the trap. By measuring the loss rates and density distributions, we determine a collisional loss rate coefficient $k_{2} = (1.43 pm 0.29) times 10^{-10}$ cm$^{3}$/s at a temperature of 2.4 mK. We show that this is not substantially changed by light-induced collisions or by varying the populations of excited-state atoms and molecules. The observed loss rate is close to the universal rate expected in the presence of fast loss at short range, and can be explained by rotation-changing collisions in the ground electronic state.
We demonstrate a scheme for magneto-optically trapping strontium monofluoride (SrF) molecules at temperatures one order of magnitude lower and phase space densities three orders of magnitude higher than obtained previously with laser-cooled molecules. In our trap, optical dark states are destabilized by rapidly and synchronously reversing the trapping laser polarizations and the applied magnetic field gradient. The number of molecules and trap lifetime are also significantly improved from previous work by loading the trap with high laser power and then reducing the power for long-term trapping. With this procedure, temperatures as low as 400 $mu$K are achieved.
We demonstrate a Magneto-Optical Trap (MOT) configuration which employs optical forces due to light scattering between electronically excited states of the atom. With the standard MOT laser beams propagating along the {it x}- and {it y}- directions, the laser beams along the {it z}-direction are at a different wavelength that couples two sets of {it excited} states. We demonstrate efficient cooling and trapping of cesium atoms in a vapor cell and sub-Doppler cooling on both the red and blue sides of the two-photon resonance. The technique demonstrated in this work may have applications in background-free detection of trapped atoms, and in assisting laser-cooling and trapping of certain atomic species that require cooling lasers at inconvenient wavelengths.
We propose and demonstrate the laser cooling and trapping of Rydberg-dressed Sr atoms. By off-resonantly coupling the excited state of a narrow (7 kHz) cooling transition to a high-lying Rydberg state, we transfer Rydberg properties such as enhanced electric polarizability to a stable magneto-optical trap operating at $< 1 mu K$. By increasing the density to $1 times 10^{12} rm{cm^{-3}}$, we show that it is possible to reach a regime where the long-range interaction between Rydberg-dressed atoms becomes comparable to the kinetic energy, opening a route to combining laser cooling with tunable long-range interactions.
A large number of $^{87}$Rb atoms (up to $1.5 times 10^{11}$) is confined and cooled to $sim 200~mu$K in a magneto-optical trap. The resulting cloud of atoms exhibits spatio-temporal instabilities leading to chaotic behaviour resembling a turbulent flow of fluid. We apply the methods of the turbulence theory based on the structure functions analysis to classify and quantify the different degrees of excitation of turbulence, including its scaling and morphological properties in the moving cloud images.
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