Matthew Steinecker

Submillikelvin Dipolar Molecules in a Radio-Frequency Magneto-Optical Trap.

We demonstrate a scheme for magneto-optically trapping strontium monofluoride (SrF) molecules at temperatures one order of magnitude lower and phase space densities 3 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  μK are achieved.

Improved magneto–optical trapping of a diatomic molecule

gradient and the laser polarization at RF frequencies. Although magneto-optical trapping of diatomic molecules is in its infancy, our results indicate that access to the ultracold regime may be possible for several molecular species, with potential applications from quantum simulation to tests of fundamental symmetries to ultracold chemistry.

Improved Radio-Frequency Magneto-Optical Trap of SrF Molecules

We report the production of ultracold, trapped strontium monofluoride (SrF) molecules with number density and phase-space density significantly higher than previously achieved. These improvements are enabled by three distinct changes to our recently-demonstrated scheme for radio-frequency magneto-optical trapping of SrF: modification of the slowing laser beam geometry, addition of an optical pumping laser, and incorporation of a compression stage to the magneto-optical trap. With these improvements, we observe a trapped sample of SrF molecules at density 2.5×105  cm-3 and phase-space density 6×10-14 , each a factor of 4 greater than in previous work. Under different experimental conditions, we observe trapping of up to 104 molecules, a factor of 5 greater than in previous work. Finally, by reducing the intensity of the applied trapping light, we observe molecular temperatures as low as 250 μK.

On the transverse confinement of radiatively slowed molecular beams

Radiative forces from near-resonant laser light can be used for cooling and slowing the motion of diatomic molecules. While radiative-force slowing can be efficient in reducing the longitudinal velocity of molecules in a beam, this method has so far resulted in relatively low fluxes of slow molecules available for loading into a trap. This is primarily due to the divergence of the molecular beam, which increases in inverse proportion to the forward velocity. In this paper, we discuss methods to transversely confine molecules as they are slowed by radiative forces. We focus in particular on a promising method that uses a microwave field tuned to the blue of a rotational transition in the molecule, to provide the confining force.We argue that with a realistic design, this approach can improve the useful flux of slow molecules from radiative slowing by a factor of ∼100.

A low-cost, FPGA-based servo controller with lock-in amplifier

We describe the design and implementation of a low-cost, FPGA-based servo controller with an integrated waveform synthesizer and lock-in amplifier. This system has been designed with the specific application of laser frequency locking in mind but should be adaptable to a variety of other purposes as well. The system incorporates an onboard waveform synthesizer, a lock-in amplifier, two channels of proportional-integral (PI) servo control, and a ramp generator on a single FPGA chip. The system is based on an inexpensive, off-the-shelf FPGA evaluation board with a wide variety of available accessories, allowing the system to interface with standard laser controllers and detectors while minimizing the use of custom hardware and electronics. Gains, filter constants, and other relevant parameters are adjustable via onboard knobs and switches. These parameters and other information are displayed to the user via an integrated LCD, allowing full operation of the device without an accompanying computer. We demonstrate the performance of the system in a test setup, in which the frequency of a tunable external-cavity diode laser (ECDL) is locked to a resonant optical transmission peak of a Fabry-Perot cavity. In this setup, we achieve a total servo-loop bandwidth of ~ 7 kHz and achieve locking of the ECDL to the cavity with a full-width-at-half-maximum (FWHM) linewidth of ~ 200 kHz.

Hyperfine structure of the B3Π1 state and predictions of optical cycling behavior in the X→B transition of TlF

The rotational and hyperfine spectrum of the

In-vacuum scattered light reduction with black cupric oxide surfaces for sensitive fluorescence detection

X^1\Sigma^+ \rightarrow B^3\Pi_1

Magneto-optical trapping of a diatomic molecule

transition in TlF molecules was measured using laser-induced fluorescence from both a thermal and a cryogenic molecular beam. Rotational and hyperfine constants for the

Magnetic Trapping of an Ultracold Gas of Polar Molecules

B

Magnetically-trapped molecules efficiently loaded from a molecular MOT

state are obtained. The large magnetic hyperfine interaction of the Tl nuclear spin leads to significant mixing of the lowest