Your research is in quantum thermodynamics. What’s that?
My research lies at the interface of two very important theories. One is quantum mechanics, which is the physics of atoms, electrons and photons. This underpins all of modern chemistry and it tells us, for example, how lasers work, how transistors work.
The second theory is thermodynamics, which is basically the physics of energy. My research sits right at the boundary of those two theories. I think about how energy behaves at the quantum scale, and what that means for powerful new technologies such as quantum computing.
What inspired you to become a theoretical physicist?
I was always a very curious child, I used to chew my parents’ ears off with questions. My dad is a chemist, so there was science in the house from an early age, and I studied physics and maths at University College Cork and then found I never stopped wanting to study. So I went on to do a PhD and built my career as a theoretical physicist. It’s one of the big privileges and joys of working in academia that you can spend your life learning and trying to understand things that nobody has understood before. That’s a rare and wonderful thing.
You recently discovered insights about how hot water can freeze faster than cold water. What drew you to that?
It goes back to Aristotle, who observed thousands of years ago that hot liquids cool faster than cold ones do. The more modern version of the story comes from a school student called Erasto Mpemba in Tanzania in the 1960s. He was making ice cream in his home economics class and noticed that a warm milk-and-sugar solution, put directly into the fridge, froze faster than a cooled one did. His teacher told him it was impossible, that it violated Newton’s laws. But the student persisted, and eventually brought it to the attention of a physicist at the University of Dar es Salaam, who called it the Mpemba effect.
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Our group in Trinity showed that this effect can also be explained in quantum mechanical systems, and now we’re applying that theory in computation, for example, to speed up certain algorithms. The moral of the story here is that you should always listen to the students.
You are the director of the new Rinn Quantum centre, what inspired you to drive that?
I worked abroad for many years, in Singapore, Italy and the UK, and when I came back to Ireland, I wanted to establish more quantum information science here. I had a Royal Society Fellowship and later a European Research Council grant, which allowed me to build my research group in Trinity and to build links with industry.
We also set up a master’s programme in quantum science, and that has been running successfully for five years now, but we noticed that many of our graduates were leaving the country after we’d worked so hard to train them. We knew we needed to generate an ecosystem to retain that talent, so we formed this new national centre called Rinn Quantum, which is funded by Research Ireland. It’s just getting started now, and I think it’s going to really boost quantum science in Ireland for the next decade.
And finally, what do you do to switch off?
In recent years I’ve started to get into mountain biking, and adventure biking in particular. I mountain biked across the north of Spain last year, which was an incredible experience. I love going out on the bikes with my kids too; that’s lots of fun.
