Squeezed Light quAntum MEMS Gravimeter - SLAM Gravimeter

Lead Research Organisation: University of Glasgow
Department Name: School of Engineering

Abstract

Work at the University of Glasgow has already taken a silicon fabricated mass on a spring fabricated using the same Micro- Electro Mechancal System (MEMS) technology to the gyroscope in all smart phones that determine orientation and improved the sensitivity by a factor of 5000. This MEMS gravimeter has the potential to be used to search for new oil & gas researches, find buried utilities quickly thereby reducing roadworks and provide an early warning for volcanic eruptions. The project aims to deliver a quantum squeezed light source with pairs of correlated photons that can be used to measure the output of the MEMS gravimeter improve the sensitivity by up to a factor of 40. The project involves developing a photodetector that can detect single photons which also has applications of rangefinding (determining how far away objects are by bouncing photons off them and timing their return) at wavelengths of light that can see through rain, mist and fog.
A key objective is to secure a UK supply chain using IQE to deliver commercial Ge on Si epitaxy for single photon detectors and Optocap to produce chip-scale vacuum packages with fibe-optic access which are essential components for the MEMS

Planned Impact

MEMS based gravity sensors have significant benefits within the area of environmental montoring (positive societal impact). This includes the development of array based gravity sensors which can be utilisied as an early warning system for volcanic erruptions via monitoring the gravity signal of magma buildup (opportunities for international exploitation /funding). Gravity monitoring has environmental benefits in terms of acquefar monitoring and guarding against the hazard of sink holes, mine shafts within brown field construction sites and water table monitoring to reduce flooding (national impact). There are also applications in the areas of geothermal basin monitoring, particularly in the develping country of Africa, where gravity monitoring could potential identify new areas to drill boreholes. This is aligned to the Global Challenge Research Fund.
Defence applications including harbour security, detection of tunnels and very dense SNM materials. The development of High Speed 2 requires ground monitoring to 20m depths beneath the track. MEMS gravimeters could provide sesimic and gravity monitoring tools, in a single package, to complement other sensing methodologies. National Joint Utilities Group estimates for 2014/15 roadworks to fix utilties costs the UK >£1.5Bn pa with 6.16M days of street occupation. Most disruption (>50%) from inability to locate buried utilities (Blacket review). Conservative estimate of £752M/year saving to UK economy from gravity detection of buried utilities to minimise roadworks. NJUG estimate £319Bn from 2013 to 2030 for utility fixing in streets so MEMS gravity could provide an enormous productivity saving.
Monitoring requires robust, reliable, and preferably cheap, sensors. Optical MEMS sensors potentially have a role in such sensing, but in order to take on this role, good packaging solutions are required that can allow sensors to stay in place for long periods without degradation.
Fibre-fed MEMS vacuum packages will have wide aications across the UK quantum technology programme. There are strong synergies with the Birmingham and Oxford Hubs which utilise ion traps/flip-chip bonded lasers and require optical access inside miniature vacuum chambers. Using a fibre-fed system could provide benfits in terms of thermal load on the package and long term stability. This will directly benefit/accelerate translation of quantum technology in the national market.
Germanium-on-silicon SPADs are enabling for automotive LIDAR and quantum radar. With 25,160 (1810 deaths) people killed or seriously injured in year ending September 2016 costing £4.43Bn to UK economy (Department for Tranport 2017).
Driver aids such as autonomous LIDAR could reduce accident numbers and economic and NHS costs.

Publications

10 25 50