1. Quantum Technology gravity sensors – first steps to aerial sensing
NSGG Postgraduate Research Symposium
Friday 12th May 2017
Daniel Roberts, Luuk Earl, Michael Wright Mohammed Uddin, Nicole Metje & Michael Holynski

2. Introduction Quantum Technology (QT) Hub
UK National Quantum Technology
Sensors and Metrology
Why develop the QT gravity sensor?
What’s wrong with existing equipment?
What are the benefits of using QT sensors?
MOT 101
Why aerial surveys?
Initial steps to aerial sensing
Trial and error
Implementation
Drone & MOT in Action
Conclusion
Next steps
Questions

3. Quantum Technology (QT) Hub
UK National Quantum Technology
In 2013, the UK government invested £270 million over a five year period into the National Quantum Technologies Programme (a collaboration of universities) to accelerate innovative technologies.
Sensors and Metrology
We are developing and delivering smaller, cheaper and more accurate and energy-efficient components for all types of industries.
Research will dramatically improve the accuracy of measuring time, frequency, rotation, magnetic fields and gravity.
Applications include: GPS navigation; dementia research; and mapping the underworld.
For more information, you can go to the Quantum Technology Hub’s website at:

4. Why develop the QT gravity sensor?
Microgravity measures minute variations of the gravitational field that is caused by density changes in the subsurface (Reynolds, 2011).
Existing sensors are affected by a multitude of factors, such as:
Density of surrounding features;
Vibrations from traffic;
Wind;
Earthquakes;
Ocean tides etc.
Using cold-atom interferometry, the gravity gradient can be measured – rather than an absolute value – which suppresses several noise sources and, ultimately, creates a sensor that is useful in every day applications
Traditional gravimeters measure gravity to a standard deviation of mGal after 30 seconds. A quantum technology gravity sensor has a standard deviation of mGal (2 x 10-8) after 1.3 seconds (Peters et al., 2001).

5. Why aerial surveys?
Traditional microgravity surveys can be time consuming and are dependent on:
Access and egress;
Weather;
Location;
Extremely sensitive (and sometimes temperamental) equipment.
Traditional airborne gravity surveys:
Relatively low resolution of 50m to 1km;
Sufficient for regional and planetary surveys;
Resolution not adequate enough for near-surface investigations.
What’s good about aerial surveys?
Easy access and egress;
Can conquer almost any terrain;
Pre-determined flight paths and survey routes;
Health and safety bonuses.
Obviously, there are also bad points about drone surveys:
For example: Small payload, problematic battery life, drop out in connectivity, falling out of the sky, hitting a plane, bird, building, human... The list is almost endless.

6. Initial steps to aerial sensing
The need for a system that can take multiple readings over minutes lead to:
Developing a magneto-optical trap (MOT) – a precursor to atom interferometry – stable enough, in laboratory conditions, to display a cloud of atoms.
Designing a 3D model for the housing in relation to the drone.
How is the sensor going to be attached to the drone?
How is it going to be powered on the drone?
How long will it last in the air?
Will the sensor be stable enough for a MOT, let alone atom interferometry?
Developing code for an Arduino in order to output various voltages to safely use and monitor the lasers used within the MOT.
Learning to fly.
Designing the more lightweight housing.
Getting the equipment off the ground.
Checking out the trial and error for the sensor + other stuff.

7. MOT 101
A magneto-optical trap (MOT) uses a system of lasers shot in an orthogonal direction to trap atoms in the centre of the instrumentation.
Atoms are pumped into the vacuum chamber.
Atoms, such as Rubidium (85Rb) can be slowed down from hundreds of metres per second to tens of centimetres per second (Diboune et al., 2016).
Checking out the trial and error for the sensor + other stuff.

8. Initial steps to aerial sensing

9. Drone in action

10. MOT in action

11. MOT in action

12. Conclusion
Traditional surveys inhibit the ability to efficiently collect microgravity data.
Developing a quantum technology microgravity sensors is paramount to increase the speed and productivity of gravity surveys.
Aerial surveys remove the possible health and safety implications of to inaccessible locations.
Research and development is at the forefront of producing new equipment for the future.
It actually works!

13. Next steps
Build a cold atom interferometer that can be mounted to the drone.
Model the quantum microgravity data.
Research sensor stability and determine any possible remediation.
Get batteries that last longer…

14. Questions?

15. References
Peters, A., Chung, K. Y. & Chu, S. (2001). High-precision gravity measurements using atom interferometry. Metrologia, 38, pp
Boddice, D. Metje, N. & Tuckwell, G. (2016). The potential for quantum technology gravity sensors. European Geosciences Union General Assembly, April, Vienna, Austria.
Reynolds, J. M. (2011). An introduction to applied and environmental geophysics. 2nd Ed. Oxford:Wiley.
Diboune, C. Zahzam, N. Bidel, Y. Cadoret, M & Bresson, A. (2016). Fiber laser systems for cesium and rubidium atom interferometry. Available online: [Accessed 12th May 2017].