My main research interest is in constructing precise experimental tests of the laws of physics. For more than a decade I've been building (with others, of course!) an experiment to measure the electron's electric dipole moment. In plainer language, this is a measurement of the shape of the electron: is it round or not? This is an exceedingly difficult thing to measure, as any deviation from roundness is known to be tiny. But ultimately it will be a worthwhile measurement as the knowledge of the electron's shape will shed light on some of the most mysterious processes in particle physics. In particular it promises to yield valuable information on the striking matter-antimatter asymmetry of the universe, one of the biggest mysteries in physics today. It also will allow us to probe processes at far higher energies than even the next generation of particle accelerators can hope to acheive.
From this work I have developed a growing fascination with cold, and hopefully one day ultracold, molecules. Atoms are rich physical systems with a variety of interactions and behaviours, but are still simple enough to be very accurately described by theory. This makes them ideal "test-benches" to precisely study and test the theory. Small molecules are also simple enough that their properties can be calculated with tremendous precision. But they differ by having additional degrees of freedom, as compared to atoms (they vibrate and rotate in a way which atoms do not). This makes it possible to probe and test aspects of physical law that would not be possible, or practical, with atoms alone. Techniques for manipulating molecules, however, are not as mature as those for manipulating atoms, making such experiments difficult. In particular, general techniques for manipulating the molecules' motion are not well-developed. I am currently (again, with others!) investigating a number of techniques which might give us such control of the molecules' motion.
I also have an amateur interest in computer programming and programming languages. I'm always on the look out for things that I can half-inch from computer science to get computers to do more of my work for me. Recent "highlights" have included thinking about how to represent, generate, and verify the correctness of hierarchical/nested digital patterns; and a rewrite-rule based computer algebra package for Dirac-notation style quantum mechanical calculations.
If you're interested, you can find out more on my personal website, http://j-star.org .
Hills DJA, Grutter AM, Hudson JJ, 2015, An algorithm for discovering Lagrangians automatically from data, Peerj Computer Science, ISSN:2376-5992
et al., 2014, Laser cooling and slowing of CaF molecules, Physical Review A, Vol:89, ISSN:1094-1622
et al., 2014, Stochastic multi-channel lock-in detection, New Journal of Physics, Vol:16, ISSN:1367-2630
et al., 2013, Shaking-induced dynamics of cold atoms in magnetic traps, Physical Review A, Vol:88, ISSN:1050-2947
Tarbutt MR, Sauer BE, Hudson JJ, 2013, Design for a fountain of YbF molecules to measure the electron's electric dipole moment, New Journal of Physics, Vol:15