Question: What was the idea you had to win 1/4 million pounds?

Chris Mansell answered on 16 Jun 2013:

There are two types of people working on quantum computers: software people (a.k.a. theorists) and hardware people (a.k.a experimentalists).

Software people have lots of different ideas but most are way too hard for the hardware people to actually try out on their quantum devices.

The hardware people, meanwhile, are exploring which is the best component for their devices: atoms, ions, photons, superconductors, etc. Each different component has unique strengths and weaknesses. Ideally, we would like a component that is awesome at everything, just like silicon is for ordinary computers.

I am mostly a hardware guy but one day I was listening to a talk on the internet by a quantum software guy. To try out this guy’s idea, you would need a quantum-mechanical system where one part of the device could very strongly interact with the rest of the device. I thought about the atoms in my lab and said to myself, “my atoms could do that.” In fact, most of my research is about getting an atom, or a small group of atoms, to influence loads and loads of atoms.

I then went and looked at what work had already been done related to this software idea. Some hardware guys specialising in photons had done an experiment on it. It was a good experiment but I realised with atoms we could a lot better. I explained all this to my supervisor and she agreed.

The software guy’s idea was a quantum-mechanical way to add up lots of numbers. The photon people only added up two numbers. Adding is hardly an impressive task but listen to this: with 100 atoms, we could add up 2^100 numbers, which is something that would take a modern computer (capable of doing 10^12 additions per second) the age of the universe (10^18 seconds) to do.

With the funding my supervisor and I won, we are actually going to try this experiment in our lab.

Our experiment may also help us learn about something called “quantum discord” that is a fairly hot topic in quantum physics at the moment. This is another thing that probably helped us get the money.