Reduction of background scattered light for future compact atom interferometers

Thomas, Hester (2022). Reduction of background scattered light for future compact atom interferometers. University of Birmingham. M.Phil.

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Abstract

Atom Interferometry has exciting potential for use in gravity surveys which has many applications, for example in civil engineering. When doing field surveys, a compact system is highly valuable; a system needs to be moved and operated by one person and last for a day of measurements operating on battery power. A compact cold atoms system is built; the final system has a weight of 17 kg, a power of 125 W and a volume of 45 l meeting the objective of < 20 kg, < 150 W and < 100 l. The system currently operates using a bench power supply not accounted for in the volume, a compact power supply has been built and is now being tested. A cloud of cold rubidium atoms is formed in the magneto optical trap, trapping 1.2 × 10^8 atoms with a loading time of 0.7 s and with a typical error of approximately 5%. This is the first step in realising a compact atom interferometer. Due to the size of the compact system any noise contributions become more significant; one way of addressing this is in reducing the contribution of scattered background light to the signal to noise and signal to background ratios. A new method of using anodised titanium to realise a blackened coating while constructing the vacuum chamber of the MOT is investigated; the reflectance of this coating is investigated and compared to that of uncoated titanium. It is found that the reflectance of light is reduced by the PCO35 coating across all investigated wavelengths, proving the PCO35 coating to be significantly less reflective than the uncoated titanium. The coating is tested in a vacuum chamber where no significant outgassing is observed, it is then used in a test prism MOT to asses compatibility with rubidium vapour; there is a possible noise reduction of 23% compared to an uncoated test system. The chamber was kept at UHV pressure for over a year and no degradation of the coating was observed. The suitability and advantages of using the PCO35 coating in a cold atoms system have been assessed and the PCO35 coating is available as a technology choice for future quantum sensor systems.

Type of Work:

Thesis (Masters by Research > M.Phil.)

Award Type:

Masters by Research > M.Phil.

Supervisor(s):