Optomechanical Sensing for Inertial, Accelerometry, and Navigation

OSIAN is a 4 year DSTL-funded experimental PhD studentship opportunity including industrial placement at DSTL Porton Down and possible placement at an Australian partner institution through DST Australia.

The project runs from October 2023 to September 2027.

Background

Optical forces arise when light, which has no mass yet carries momentum, is deflected through interaction with a material object. Lasers of power \(\sim 100\,\text{mW}\) focused to a spot \(\sim10\,\text{um}\) exert significant forces on objects \(\sim100\,\text{nm}\) across. These nanoparticles can be levitated, in vacuum, and manipulated by modulating the optical field. Interferometric measurement and active feedback techniques allow these systems to approach quantum limits of position sensitivity.

This research is part of the field of levitated optomechanics. Since the seminal demonstration of feedback cooling to sub-Kelvin temperatures [Gieseler 2012], the field has seen rapid and intense research, with recent achievements including cooling to the quantum-mechanical ground-state with optical cavities [Delić 2020] and in a cryogenic environment [Tebbenjohanns 2021].

This project will implement an accelerometer through a robust experimental platform, which bridges levitated optomechanics and fiber telecommunications technologies, such as lasers, modulators, and detectors.

The immediate goals are to build classical devices, where the nanoparticle is treated as a point-like object undergoing Newtonian motion and subject to classical noise sources. Several interesting approaches from macroscopic, traditional devices translate and are promising in terms of sensitivity, robustness, reliability, and bandwidth.

Development of the robust platform provides a route towards quantum devices, where the particle is treated as a quantum mechanical object subject to superposition and decoherence. Establishing capability in this classical space is a necessary step towards realising fully quantum-limited devices, for which there are a number of exciting theoretical proposals in accelerometry with predicted sensitivities \(\sim10^{-17}\,\text{g}/\sqrt{\text{Hz}}\) [Pontin 2018].

[Gieseler 2012] Gieseler, Deutsch, Quidant, Novotny; PRL 109 103603 (2012)
[Delić 2020] Delić et al.; Science 10.1126/science.aba3993 (2020)
[Pontin 2018] Pontin et al.; New J. Phys. 20 023017 (2018)
[Tebbenjohanns 2021] Tebbenjohanns et al.; Nature 595 378-382 (2021)