Question: Wouldn't going on a conference abroad be more like a holiday rather than work, and also, how does shining lasers in diamonds make better computers?

Philip Dolan answered on 13 Jun 2011:

Well, I guess it wouldn’t be super duper hard work, but you’d be surprised. Most of the conferences have full timetables (from 9am until 6pm) and during the breaks, and often at breakfast and dinner as well you will be chatting about science with all of the other people there.

This generally means that you have to be paying attention, thinking about your work and science and what work you could do with this guy or that group etc… for quite a long time each day.

As for the diamonds on computers – that’s quite a long explanation. I’ll try and be quick:

Normal computers use 1’s and 0’s (known as ‘bits’). In your computer’s hard disk this is a tiny little magnet that points up or down. In the processor this is a little circuit that either lets electricity flow, or stops it.

Quantum mechanics (this is a theory that you might learn a little bit about in sixth form) allows us to put something into two states at the same time. But it has to be something really small (like an electron might be in two places at once). It’s also really tough to do, cause if anything bumps into the electron it suddenly decides which of the two places it’s in.

This means we’d need to stop air molecules (they’re thrashing around your classroom right now like crazy) light, so it’d have to be completely pitch black, and absolutely everything else from disturbing it (even things like mobile phone signals, TV signals, sounds, and vibration).

If we do manage to keep it in 2 places at once, then it’s like a ‘1’ and a ‘0’ at the same time.

So for 1 ‘quantum bit’ or qubit’ you’d need 1 pair of ‘bits’ (in a regular computer), a ‘1’ and ‘0’.

But for 2 ‘qubits’ we kinda have lots of ways of arranging the 1’s and 0’s. We can have
1 – 1,
1 – 0,
0 – 1,
0 – 0.

So we’d need 4 pairs bits in a regular computer.

For 3 ‘qubits’ you’d need
1-1-1,
1-1-0,
…,
etc,
0-0-0.
In total – 8 pairs of bits.

If you have 4 qubits, 16 regular bits. By the time we have 30 qubits you’d need 1, 073, 741, 824 regular pairs to show all of the combinations. If we could have a quantum computer with 300 qubits (this might only be 300 electrons kept in their delicate ‘two-states-at-one-time) it’d take all of the atoms in the universe to represent all of the combinations!

The key to it all is keeping the electrons from bumping into anything. So we use the diamond as a kind of cage, to keep everything else out, and keep our electrons in their delicate two-states-at-one-time. We use the lasers to delicately nudge the electrons into being in two places at once.

I hope that made (a little) sense!

It’s really a very tough idea to explain, even to other scientists so don’t worry if it seems difficult.

Thanks for asking tho!

Phil