Research Fellow in Optomechanics for Gravimetry

2 days left

United Kingdom
£30,942 to £31,866
Dec 28, 2020
Jan 27, 2021
Organization Type
University and College
Full Time
You will join the research group of Professor Hendrik Ulbricht ( ) at the Quantum, Light and Matter (QLM) research division at the School of Physics and Astronomy (P&A) on a joint project with Dr Jize Yan from the School of Electronics and Computer Science (ECS) at the University of Southampton (UoS), UK.

Research will be on the recently awarded EPSRC project "Integrated levitated optomechanical gravimeter", which is an experimental physics project on waveguide based levitated optomechanics in vacuum. The ultimate goal of this research project is to realise a platform for ultra-precise sensing of forces such as gravity. Current highly sensitive gravimeters, such as superconducting spheres, atom interferometers, and torsion pendulums, suffer from high manufacture and maintenance cost (up to £400k), bulky size (as large as 2.5m^3) and slow measurement speed (typically 1 hour). We propose an exciting innovation in quantifying gravity, based on the frequency measurement of the gravity-induced precession in an optically levitated fast-spinning particle. This novel levitated optomechanical systems (LOMS) gravimeter can be fabricated on a silicon wafer with wafer-level vacuum encapsulation, making its footprint as small as one mm^2. The small size device is mass-producible with a fabrication cost potentially less than £4k. The proposed research uses the analogy of the precession of the Earth, a slow and continuous change in the orientation of the Earth's rotational axis induced by the gravity of the sun, to develop the novel gravimeter. In December 2018, our research for the first time revealed that the precessional motion also appears in sophisticatedly designed LOMS and that optical scattering techniques can precisely measure the frequency of precession U9. Our calculation predicts that levitated rotating particles of 10um diameter can achieve the sensitivity of 10^-9 g/sqrt(Hz) and a very fast-spinning particle (GHz reported in 2018 x19) can achieve 10^-11 g/sqrt(Hz) sensitivity, respectively. The novel gravimeter can also measure the acceleration due to the Einstein equivalence principle. Thanks to the ultra-high Quality-factor (7.7x10^11 demonstrated in 2017 x3) of the rotating particles, the novel sensor will have the potential to cover 11 orders of magnitude of acceleration measurement. Moreover, using the advanced silicon fabrication technique, we will be able to differentiate the centre-of-mass and the centre-of-optical-force of the levitated particle, in order to optimise the range of the gravity (or acceleration) induced torque, and correspondingly design e sensing range and sensitivity of the acceleration, e.g. 10^-6 m/s^2 to 10^5 m/s^2 to cover the seismic and mining health monitoring applications or 1 m/s^2 to 10^11 m/s^2 for fundamental physics research. The sensor only requires short integration times (1ns to 100s, depend on the precession frequency). Thus, it can complete the measurement very rapidly. This novel precession sensing principle can also be utilised to measure force, strain, charge and mass, with similar ultra-wide dynamic range and ultra-high sensitivity potentially. The innovative gravimeter (accelerometer) can be a powerful tool for investigating fundamental physics questions in gravitation, which are pressing and very hard to access experimentally due to the weakness of the gravitational interaction if compared to other interactions. The proposed research can also provide a platform for quantum manipulation of mesoscopic mechanical devices in the nano-scale regime and can serve as a testbed for theoretical predictions.

To be successful you will have a PhD* or equivalent professional qualifications and experience in experimental quantum physics. You should have expertise in at least one of the following experimental research fields: cavity optomechanics, trapped ions and knowledge about experimental techniques including parametric feedback cooling, vibration isolation and cancellation, nanofabrication, vacuum techniques, nanoparticle trapping and control, inertial and force sensing.

The post is available with a start date as soon as possible, but before the beginning of February 2021 and is initially for two years due to funding restrictions with a possibility of an extension.

Equality, Diversity and Inclusion is central to the ethos in Physics and Astronomy. We are strongly committed to diversity in both the academic and student population, and in recognition we were awarded an Athena SWAN Silver award in 2018 and the Institute of Physics Project Juno Champion status in 2019. Physics and Astronomy gives full consideration to applicants that wish to work flexibly, including part-time, and due consideration will be given to applicants who have taken a career break. The University has a generous maternity policy** and onsite childcare facilities. For further information please visit

The University of Southampton is in the top 1% of world universities and in the top 10 of the UK's research-intensive universities. The University of Southampton is committed to sustainability and being a globally responsible university and has recently been awarded the Platinum EcoAward. Our vision is to embed the principles of sustainability into all aspects of our individual and collective work, integrating sustainable development into our business planning, policy-making, and professional activities.

*Applications for Research Fellow positions will be considered from candidates who are working towards or nearing completion of a relevant PhD qualification. The title of Research Fellow will be applied upon successful completion of the PhD. Prior to the qualification being awarded the title of Senior Research Assistant will be given.

**subject to qualifying criteria

For inquiries about the project please contact:

We aim to be an equal opportunities employer and welcome applications from all sections of the community.

Similar jobs

Similar jobs