Aaron W Jones | Portfolio

Experimental & Instrumentation

Future gravitational wave detectors, such as Einstein Telescope and Cosmic Explorer will transition to very cold mirrors. The mirrors will be made of pure Silicon and the lasers will operate at a different wavelength.

In this project, I have designed a coupled cavity with adaptive optics. I have installed a free running laser operating at 1995nm and test masses into small suspensions. Together with a team of students, we have cleaned two vacuum tanks and installed a pre-isolators into them. I have also led the setting up up three clean rooms and assembled a 8 stage seismic isolator.

Since lasers are beams of light, very far from the centre of the beam the intensity of the field goes to zero (no light). Previous research tells us that far from any scattering source (air molecules, edges, etc), this intensity must vary smoothly. As a result, only certain spatial patterns of laser are possible, these are called spatial modes and some are shown right. The typical image of a laser (known as the TEM00, HG00 or fundamental mode) is shown top left.

For a given laser, there are unique sets of spatial modes that the laser can support. If there is light present in several of these modes, new patterns can emerge from interference.

Unfortunately, mismatches in modal basis cause losses of entangled photons in quantum systems. In this project, I am investigating active optics to mitigate the effect.

In cold atom instruments such as, atomic interferometers and optical clocks, very stable lasers are used to move electrons in the cold sample of atoms between different atomic energy levels. The frequency of these lasers is stabilized with an optical cavity. As the temperature of this cavity rises, it will expand due to thermal expansion, and so the frequency of light which resonates in this cavity will change, causing the laser to drift away from the resonances in the atoms.

Usually an analogue temperature control system is used, however, very sensitive devices require multiple layers of temperature control. I designed a digital temperature controller using an Arduino and some additional custom electronics. This allowed each layer to communicate, achieving more stable control. An Arduino was chosen because it is a friendly system for future users to work with. Stability of (3 ± 1)mK was obtained for an open system, with breadboard design.

See my report and code.

Computational Modeling & Programming

I have been leading an effort to accurately model and understand the opto-mechanical interactions and noise budgeting at the LIGO 40m prototype. You can find the source code on git.ligo.org

In an Atomic interferometer, a cloud of atoms is prepared in a common electronic state. Lasers are then used to put the atoms in a 50:50 quantum superposition of states. By interfering these states with each other, it is possible to make statements about the fields encountered by the atoms on their paths. Unfortunately, the lasers carry some noise. Optical cavities have been proposed to address some of these noise issues. This could promise significant advances for both gravitational wave detectors and portable atom interferometers.

In this work, I developed a computational model of atoms interacting with a generic time domain laser field. I developed the model for Raman interactions and verified it against known test cases, chose a suitable integration routine and characterized the errors. We found that for reasonable choices of parameters, cavity-assisted Raman interferometry was not viable. We further developed the routine for multi-photon Bragg transitions and explored the limits. The results are published in Physical Review A, ArXiv and Proceedings of Science. You can also check out Chapter 7 of my doctoral thesis

The image right is used under the Creative Commons Attribution 4.0 License. The original content can be found here.

I built the Birmingham Environment for Software Testing (BEST) shortly after my work verifying numerical models for the cavity assisted atom interferometry paper. I found that each time I modified part of the model, to introduce a new feature or speed up the execution time, I would need to re-run lots of detailed simulations to ensure I hadn't introduced a bug. These simulations could take hours and so I wanted to automate the process.

The solution I was looking for was not unlike Continuous integration in software engineering. Unfortunately, unlike software engineering my builds were not fast and my tests were very slow and computationally expensive. I found common tools like Jenkins and GitLab were not suitable for my tests.

I built BEST to alleviate these problems, it can be used standalone or it can hook into GitLabs CI system. It supports grouping of errors by return codes, so you can separate programming errors from numerical/science errors. It supports invoking multiple interacting languages (e.g. C++, Python, Bash) all in one test, so you can have a script (e.g. python) that tests your program (e.g. C) in some large parameter space.

If you are interested in using BEST, or setting up your own server please do let me know.

Update 2021: BEST is no longer used for Finesse3 development. All the desired functionality could now be found in the updated versions of pytest and gitlab-ci.

I developed a Newtonian model of the solar system as part of my undergraduate studies. The aim was to predict the trajectory of a satellite undergoing a gravity assist (e.g. voyager), but the program models all of the gravitational interactions between the planets with an adaptive step size routine written in C++.

See my report and code.

I developed a fully encrypted database as part of a course C++ programming. The Fast Light Toolkit (FLTK) was used for a GUI and the Quincy IDE was used for development.

See my report and code.

Public Talks, Engagement & Outreach

• Major Projects
• Outreach Talks
• Festivals & Organization

Major Projects

The Gravity Synth is a musical performance that is formed by the fusion of a Miniaturized Gravitational Wave Detector and a modular synthesizer.

The project explores a new way of engaging both artists and the general public. I built a working, portable, robust Michelson Interferometer, that was capable of interfacing with a modular synthesizer. Together with the modular synthesizer, the device is an entirely new musical instrument.

The device provides an immediate source of engagement to artists who can become inspired by Gravitational Waves and can incorporate this into their work.

I have been leading this project for a number of years now, right from the initial build, through the first prototypes to the final build. I give regular talks about the project to artists, scientists and the general public.

The Royal Society Summer Science Exhibition is a week-long public engagement event held at the Royal Societies London headquarters. I joined as part of the Birmingham group, alongside a number of other UK universities working in Gravitational wave research. Considered by some to be the premier public engagement event, attended by media, politicians as well as the general public.

The Birmingham group presented a large interactive tabletop Michelson interferometer . The interferometer was previously part of an exhibit in the Thinktank Futures gallery and needed to be upgraded with a real-time signal readout and large plastic buttons to modulate the length of the arms, mimicking the effect of a Gravitational Wave passing though detector.

There were 4 buttons, each mimicking the effect of a different Gravitational Wave source on the detector. They worked by moving one of the mirrors a small amount to represent a changing space-time interval. The light would then interfere as it does in a gravitational wave detector (e.g. LIGO/Virgo). The interference pattern would be visible (as in the original exhibit), but also read by a photo diode and plotted real time on the screen.

This presented a number of technical challenges, for safety reasons we restricted ourselves to 1mW of light (same as a laser pointer), this was enough to produce a visible pattern. The photo-diode was placed behind the screen with a small pinhole providing light to it. However, after accounting for losses only a few hundred microwatts of power (which is comparable to a bright room) reached the photo-diode and so the signal was noisy.

Alongside two other PhD students, we solved the problem by only allowing certain frequencies of light to pass through and be amplified. Then averaging was applied in software.

I also developed the internal electronics for the button box, reading the signal and relaying over USB. Mounting this into the box with reliable joints that could be fixed away from the lab presented its own set of technical problems.

• 1 October 2020 IOP West Midlands - Gravitational Waves
  Recording on YouTube
  An introduction to Gravitational Waves, the techology we used to detect them and the app Chirp.
• 3rd September 2019 BBC Digital Planet - World Service Radio Interview.
  I spoke on the BBC Digital Planet programme about gravitational wave detector technology and my Gravity Synth project with Leon Trimble.
• 16th February 2019 TEDx - The Gravity Synth (Invited Talk)
  Official Video:
  
• 21st November 2018 Astronomy In the City (Invited Talk) - Instruments Gravitational Wave Detectors and Musical Instruments Alike.
  
  
• 27th July 2018 Lunar Festival (Invited Talk) - Gravitational Waves.
• 16th May 2018, The Botanist, Birmingham. Pint of Science (Invited Talk) - How Improvements To Gravitational Wave Observatories Enabled GW-Multi-Messenger Astronomy. LIGO Document Link (login required).
• 16th May 2018, 1000 Trades, Birmingham. Maker Monday (Invited Talk) - Audio Synthesis Using Miniature Model Gravitational Wave Detectors.
• 21st March 2018, Whitworth Art Gallery. Future Sessions Launch Party (Invited Talk) - I presented for 10 minuets on the significance of Gravitational Wave Instrumentation to contextualize a Gravity Synth performance. This was a real opportunity to artists about science.

• 26th-30th September 2018 Gravity Fields Festival I won £500 funding plus accommodation to run a three day Gravitational Waves themed science exhibit including the Gravity Synth and planetarium.
• 27th-29th July 2018 Lunar Festival I built and installed a 3 day day art installation centered on Gravitational Wave technology. I also gave a talk (see above) alongside a Gravity Synth performance later in the evening.
• 10th March 2018 Seventh Wave Festival of Electronic Music I presented the Gravity Synth as a preliminary trial using this performance to engage with music enthusiasts and artists about science.
• 3rd October 2017, Malvern Malvern Festival of Innovation. I organized the groups attendance at the Malvern Festival of Innovation. We developed a new interactive planetarium exhibit for this event on cosmological distance scales.
• Summer 2017 Procured a 5.5m planetarium for the research group, trained fellow postgraduates and the student astronomical society to use it and built a website for it.
• 1st-9th July 2017 Royal Society Summer Science Exhibition (see above).
• 15-17th May 2017 Co-organized Pint of Science Atoms to Galaxies event. Larger than a usual Pint of Science, our event was held at Millennium Point and sold around 200 tickets each night. I built two new exhibits including a Rubins Tube and a Michelson Interferometer. We won funding from IoP to support the venue hire costs.
• Spring 2017 Built Gravity Synth! initial prototype.
• 25th Feb 2017 Organized visit to Big Bang Fair at Leicester Grammar School about Gravitational Waves.
• 1st Nov 2016 Organised visit to William Brookes Sixth Form about Gravitational Waves and Quantum Technology.
• 21st - 22nd September 2016, Grantham, UK Gravity Fields Festival. Presented Gravitational Waves exhibit.
• 16-19th March 2016, Birmingham NEC, UK Nuclear Institute Big Bang Fair. I organized my attendance at the event and drafted a business case to my employer to allow me to attend and cover my costs. I was awarded a Certificate of Appreciation in return. This was the first STEM outreach I had done and I immediately recognized the importance, both outside the university sector and within. Big Band Fair Marketing Video.

Teaching

I developed content for and delivered a mini-lecture series for a new module at the University of Western Australia. The topic was Introduction to Gravitational Wave Detectors, which sat within the High Energy Physics (Introduction to Gravitational Wave Astronomy) module. The unit was for Physics Masters students.

In the first year of my PhD I co-developed a new second year python module, teaching students how to do simple numerical modeling in a Jupyter notebook. The module is automatically marked. I continued to work as a PGTA for the following two years while the course was in its infancy.

I worked as a PGTA for three years at the University of Birmingham. I marked reports and helped students develop skills to solve the problems they had been set.