306 research outputs found
Precision Test of Mass Ratio Variations with Lattice-Confined Ultracold Molecules
We propose a precision measurement of time variations of the proton-electron
mass ratio using ultracold molecules in an optical lattice. Vibrational energy
intervals are sensitive to changes of the mass ratio. In contrast to
measurements that use hyperfine-interval-based atomic clocks, the scheme
discussed here is model-independent and does not require separation of time
variations of different physical constants. The possibility of applying the
zero-differential-Stark-shift optical lattice technique is explored to measure
vibrational transitions at high accuracy.Comment: 4 pages, 4 figure
Large-Area, Low-Noise, High Speed, Photodiode-Based Fluorescence Detectors with Fast Overdrive Recovery
Two large-area, low noise, high speed fluorescence detectors have been built.
One detector consists of a photodiode with an area of 28 mm x 28 mm and a low
noise transimpedance amplifier. This detector has a input light-equivalent
spectral noise density of less than 3 pW/Hz^1/2, can recover from a large
scattered light pulse within 10 us, and has a bandwidth of at least 900 kHz.
The second detector consists of a 16 mm diameter avalanche photodiode and a
low-noise transimpedance amplifier. This detector has an input light-equivalent
spectral noise density of 0.08 pW/Hz^1/2, also can recover from a large
scattered light pulse within 10 us, and has a bandwidth of 1 MHz.Comment: Submitted to Review of Scientific Instrument
Energy Dependence of Scattering Ground State Polar Molecules
We explore the total cross section of ground state polar molecules in an
electric field at various energies, focusing on RbCs and RbK. An external
electric field polarizes the molecules and induces strong dipolar interactions
leading to non-zero partial waves contributing to the scattering even as the
collision energy goes to zero. This results in the need to compute scattering
problems with many different values of total M to converge the total cross
section. An accurate and efficient approximate total cross section is
introduced and used to study the low field temperature dependence. To
understand the scattering of the polar molecules we compare a semi-classical
cross section with quantum unitarity limit. This comparison leads to the
ability to characterize the scattering based on the value of the electric field
and the collision energy.Comment: Accepted PRA, 10 pages, 5 figure
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