Abstract
Recent advances in the understanding and control of cold atom systems have resulted in devices with extraordinary metrological performance. To further improve the performance in these systems, additional methods of noise reduction are needed. Here, we examine the noise reduction possible from vacuum compatible low reflection coatings in cold atom systems by characterizing a black coating and its compatibility in a Magneto-Optical Trap (MOT). We demonstrate that the commercially available PCO35® coating provides low-reflectivity surfaces that are ultra-high vacuum compatible. The reflective properties of the coating are compared to titanium, a common vacuum chamber material, and the reduction to scattered light is characterized over a range of angles and wavelengths. The outgassing properties of the coating are measured to be less than that of the vacuum system used to test the coating, which is limited to 3 × 10−8 mbar L cm−2 s−1. The coating is applied to a vacuum chamber housing a rubidium prism MOT, and its vacuum compatibility is assessed and compared to an identical non-coated system. Finally, the effect of scattered light reduction in a generalized system is explored theoretically. These results show promise for reducing background light in cold atom experiments via the use of low-reflectivity coatings.
Highlights
The exceptional performance of cold atom systems has enabled measurements of the fine structure constant,1 the equivalence principle,2 the gravitational constant,3 and the redefinition of the kilogram as part of a watt balance4 and resulted in several proposals for gravitational wave detection.5–7 In addition, quantum technologies based on cold atoms have begun to move out of the lab and into the real world, where they are expected to address a number of different applications.8–10 Despite this success, there is still scope to make these devices more sensitive and for even more precise measurements to be made.In a cold atom system, one or more photodetectors are often used to measure light produced by atom fluorescence
The potential improvements of a reduction in background light levels were explored for cold atom systems
The optical properties of a coating were tested compared to a titanium surface, a common vacuum chamber material
Summary
Quantum technologies based on cold atoms have begun to move out of the lab and into the real world, where they are expected to address a number of different applications.8–10 Despite this success, there is still scope to make these devices more sensitive and for even more precise measurements to be made. Background light in cold atom systems often originates from specular reflections off of vacuum chamber walls and fluorescence from background atoms These effects have been observed to introduce systematic shifts and noise sources, as well as loss of contrast in many cold atom systems including gyroscopes, clocks, and gradiometers.. These effects have been observed to introduce systematic shifts and noise sources, as well as loss of contrast in many cold atom systems including gyroscopes, clocks, and gradiometers.14 Reducing these noise sources will be important when realizing current proposals for cold atom experiments targeting fundamental physics.. The tests and theory presented provide a tool set to allow for the potential benefits of low-reflectivity coatings in existing systems to be evaluated
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