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Register a new userOne dimensional magneto-optical compression of a cold CaF molecular beam
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We demonstrate with a RF-MOT the one dimensional, transverse magneto-optical compression of a cold beam of calcium monofluoride (CaF). By continually alternating the magnetic field direction and laser polarizations of the magneto-optical trap, a photon scattering rate of $2pi times$0.4 MHz is achieved. A 3D model for this RF-MOT, validated by agreement with data, predicts a 3D RF-MOT capture velocity for CaF of 5 m/s.
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We demonstrate significantly improved magneto-optical trapping of molecules using a very slow cryogenic beam source and RF modulated and DC magnetic fields. The RF MOT confines $1.1(3) times 10^5$ CaF molecules at a density of $4(1) times 10^6$ cm$^{-3}$, which is an order of magnitude greater than previous molecular MOTs. Near Doppler-limited temperatures of $340(20)$ $mu$K are attained. The achieved density enables future work to directly load optical tweezers and create optical arrays for quantum simulation.
Employing a two-stage cryogenic buffer gas cell, we produce a cold, hydrodynamically extracted beam of calcium monohydride molecules with a near effusive velocity distribution. Beam dynamics, thermalization and slowing are studied using laser spectroscopy. The key to this hybrid, effusive-like beam source is a slowing cell placed immediately after a hydrodynamic, cryogenic source [Patterson et al., J. Chem. Phys., 2007, 126, 154307]. The resulting CaH beams are created in two regimes. One modestly boosted beam has a forward velocity of vf = 65 m/s, a narrow velocity spread, and a flux of 10^9 molecules per pulse. The other has the slowest forward velocity of vf = 40 m/s, a longitudinal temperature of 3.6 K, and a flux of 5x10^8 molecules per pulse.
Cooling the rotation and the vibration of molecules by broadband light sources was possible for trapped molecular ions or ultracold molecules. Because of a low power spectral density, the cooling timescale has never fell below than a few milliseconds. Here we report on rotational and vibrational cooling of a supersonic beam of barium monofluoride molecules in less than 440 $mu$s. Vibrational cooling was optimized by enhancing the spectral power density of a semiconductor light source at the underlying molecular transitions allowing us to transfer all the populations of $v=1-3$ into the vibrational ground state ($v=0$). Rotational cooling, that requires an efficient vibrational pumping, was then achieved. According to a Boltzmann fit, the rotation temperature was reduced by almost a factor of 10. In this fashion, the population of the lowest rotational levels increased by more than one order of magnitude.
We demonstrate an atom interferometer that uses a laser-cooled continuous beam of $^{87}$Rb atoms having velocities of 10--20 m/s. With spatially separated Raman beams to coherently manipulate the atomic wave packets, Mach--Zehnder interference fringes are observed at an interference distance of 2L = 19 mm. The apparatus operates within a small enclosed area of 0.07 mm$^2$ at a bandwidth of 190 Hz with a deduced sensitivity of $7.8times10^{-5}$ rad/s/$sqrt{{Hz}}$ for rotations. Using a low-velocity continuous atomic source in an atom interferometer enables high sampling rates and bandwidths without sacrificing sensitivity and compactness, which are important for applications in real dynamic environments.
Laser slowing of CaF molecules down to the capture velocity of a magneto-optical trap (MOT) for molecules is achieved. Starting from a two-stage buffer gas beam source, we apply frequency-broadened white-light slowing and observe approximately 6x10^4 CaF molecules with velocities near 10,m/s. CaF is a candidate for collisional studies in the mK regime. This work represents a significant step towards magneto-optical trapping of CaF.
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