Pint of Science – Particles Go Quantum


On Monday 18th May, Dr Matt Himsworth and Dr Simone de Liberato from the Quantum Light and Matter group in physics will be at Avondale House talking about their research, accompanied by Martin Fogel, artist in residence, and his guitar.

Matt Himsworth is a postdoctoral fellow conducting research into ultracold matter, cooling atoms to the lowest temperatures possible. How cold is cold? “Colder than anything in the universe -” Matt explains “space is cold, but it still has some left over heat from the big bang, so it has a temperature of about 2.7K.” In other words, 2.7°C above absolute zero (-273.15°C). But the atoms Matt is working with are cooled below 2.7K, to a millionth of a degree above 0K, absolute zero.  When you have atoms this cold, you can observe quantum effects happening; we think of quantum physics as being things on a very small scale, but with atoms with very low temperatures, according to the Heisenberg uncertainty principle,  if we know their velocity, or momentum, very precisely, there is a large uncertainty in their exact position. When you have around a million atoms or so, this “fuzziness”, as Matt calls it, in their position, becomes larger than the separation between atoms, resulting in an “homogeneous blob” of atoms which you can’t tell apart from one another.

A diagram of a "Mach-Zehnder" Interferometer
A diagram of a “Mach-Zehnder” Interferometer

Matt works with atom interferometers. Time for some physics – laser interferometers are devices used to split a beam of light, send it via two paths, and make it reconverge, to create interference patterns in certain circumstances, such as if the whole system is rotating, making the path that one beam has to travel slightly longer. You can use interferometers to do this same process, but with atoms; in quantum mechanics, the atom acts as a probability wave, and therefore can be put through an interferometer to interfere with itself. (Stay with me, it gets better…) The reason you might want to do this with atoms is that they have much smaller wavelengths than light, so the process is much more sensitive to any small motions. As well as this, atoms travel much slower, so the difference between the path lengths of the two beams will be increased, making the interference pattern more pronounced.

Dr Himsworth’s work has possible applications in creating navigation systems, due to its sensitivity to motion, as well as sensing things underground, such as pipes – we currently only know about 30% of what’s underground – and also, this is how atomic clocks work, which count time to unprecedented levels of precision, the most accurate of which in the world is at the National Physical Laboratory (NPL), in London. All of these applications mean that the government recently invested £250 million into this area of research.

The most accurate timekeeper in the world
The most accurate timekeeper in the world

Matt did his undergraduate degree at Southampton, in Physics with Space Science. I asked why he moved discipline: “I wanted to create big propulsion engines for rockets, something with impressive explosions, but discovered you basically had to be American to go into that. I took a lasers module, and the lecturer, Anne Tropper, showed us a picture of an optical trap device, and it looked so science fiction, with a vacuum chamber with lasers, and a glowing ball of atoms which you can use to create supercomputers – I had to make one!” He managed to then get a PhD in interferometry, and finding new ways to cool atoms to low temperatures, and has now carried on in the QLM group as a postdoc.

Also speaking at the event is Dr Simone De Liberato, whose research is in a very new field of quantum physics, cavity quantum electrodynamics. In short, he traps atoms and light together in between two mirrors, and observes very interesting quantum effects that happen when you combine them. This field has really advanced in the last 20 years ago. Quantum Electrodynamics (QED) is one of the most accurate theories ever produced, for which we have Rchard Feynman to thank. Matt says he doesn’t know yet what Simone will be speaking about exactly, other than the interaction of light and matter, but says that he is a very good speaker and he is interested to see how he will bring QED to a pub setting!

Martin Fogel
Martin Fogel

Joining Matt and Simone is Martin Fogel, an incredible guitarist from Sweden, who has been working with them and trying to understand how to portray quantum effects through art. Because they are dynamic things, based on waves, it is difficult to do statically, through painting or other means, but musically he tries to interpret these abstract ideas. The evening will also include demonstrations in holography, and a pub quiz. Matt, Simone and Martin will be at Avondale House on Monday 18th May.


More articles in Pint of Science
  1. A Pint of Science
  2. Pint of Science – Making and Maintaining Connections
  3. Pint of Science – The Immune System and The Brain
  4. Pint of Science – Particles Go Quantum
  5. Pint of Science – Regenerating Organs in the Lab
  6. Pint of Science – Time Flies: A Brain Perspective
  7. Pint of Science – Understanding Addiction
  8. Pint of Science – Life: From Surface to Deep Sea
  9. Pint of Science – To Infinity… And Beyond!
  10. Pint of Science – The War On Cancer
  11. Pint of Science – Light: The Future of Data
  12. Pint of Science – Under the Crust
  13. Pint of Science – Análogos de Marte – Madrid
  14. Pint of Science Madrid – Preparing for Mars

Physics student and regular freelance science communicator, shooting for the stars. I'm your Science Editor and with the help of a team of talented writers, strive to bring you the most interesting and relevant science stories.

Leave A Reply