Physics & Astronomy ETDs

Publication Date

Spring 4-19-2022

Abstract

Atom-based inertial measurement systems can measure acceleration and rotation very precisely in the laboratory. The central element of these systems is atom interferometry where the phase shifts are sensitive to inertial forces experienced by the atom. This phenomenon has been used to make atom-based gravimeters, gradiometers, and gyroscopes. Recent effort has been made to make these systems more compact which require small size, light weight, and low power (SWaP). Nano-fabricated waveguides, such as photonic waveguides or optical nanofibers, offer a promising avenue to meet these goals. They have dimensions comparable to the guided light’s wavelength producing a mode that not only propagates within the waveguide but also without in the form of an evanescent wave. This mode has a small area that is comparable to the atom’s absorption cross section providing a highly efficient atom-light interaction. This property reduces the laser power required for efficient manipulation of atomic systems. In addition, photonic waveguides on silicon substrates provide the added benefit of further reducing the system size and being intrinsically scalable. In this thesis, I detail two projects that aim to help progress the implementation of these platforms for use in inertial measurements.

Most of this thesis focuses on the nanofiber platform. I detail the construction of a fiber pulling rig used to fabricate tapered optical fibers with sub-micron diameters, so-called nanofibers. The fiber pulling rig has the capability of tailoring the fiber geometry for use as a 1-dimensional atom guide. Using a scanning-electron-microscope, we verify the accuracy and repeatability of nanofiber fabrication. In addition, we experimentally demonstrate trapping of cesium atoms around a nanofiber using a dual-color optical trap with magic wavelengths. This trap implements far detuned laser beams that repel and attract atoms near the surface to produce a potential well where they can be trapped. We measure trap lifetimes up to 26 ms with an optical depth (OD) of 5.5 ± 0.3, corresponding to about 70 atoms. Additionally, the coherence properties of the trapped atoms are probed using microwave spectroscopy. I also discuss theoretical efforts in understanding the effects of driving Raman transitions with fiber guided fields.

Finally, I present an atom chip with a suspended optical rib waveguide extending across a cutout enabling an atomic cloud to be overlapped with the waveguide as a source for the trap. Simulations show that a dual-color trap with a trap depth of 350 μK can be generated using a total power of 6 mW. To demonstrate the chip designs are suitable for this type of trap, we experimentally test several waveguide designs and demonstrate power-handling capabilities close to 30 milliwatts before breaking. In addition, we measure the effect of the waveguide on the atom cloud by measuring the atom number when the atomic cloud is overlapped with the waveguide. Using fluorescence imaging, we measure the initial atom number in the cloud and find that it is reduced by an order of magnitude when overlapped with the waveguide.

Degree Name

Physics

Level of Degree

Doctoral

Department Name

Physics & Astronomy

First Committee Member (Chair)

Ivan Deutsch

Second Committee Member

Grant Biedermann

Third Committee Member

Elohim Becerra

Fourth Committee Member

Victor Acosta

Language

English

Keywords

nanofiber, tapered optical fiber, atom interferometry, waveguide

Document Type

Dissertation

Comments

This is a re-submission of my dissertation. I re-numbered the pages so that the dedication page is page iii. Previously it read page ii.

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