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TOM: I'm kind of expecting it to be this enormous
bit of equipment that's sitting round here somewhere.

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JACQUES: No, no, you're almost there. It's
just in... this cupboard.

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TOM: This cupboard!

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JACQUES: So here is... the quantum computer.

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TOM: That little chip there?

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JACQUES: In fact, what it really is, is just
this -- you see the very thin black strip

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in the middle. That's actually the chip.

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Most classical computers store information
on big macroscopic things. And what we do

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at the Centre for Quantum Photonics, and what
other people are doing around the world, is

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try to store that information on single particles.
Or single atoms. In our case, we're going

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to do it with photons, particles of light.
And then you start inheriting the beautiful

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rules of quantum physics.

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TOM: So this is double-slit experiment, this
is something that is a particle and a wave

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at the same time.

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JACQUES: And if you imagine these -- your
two slits, and we say, well, a photon going

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through the top slit is a 0, and a photon
going through the bottom slit is a 1, now

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when we run this experiment we've got the
idea that we've got both a 0 and a 1 at the same time.

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TOM: So by cleverly cancelling out those waves,
adding them, you can kind of design an algorithm?

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JACQUES: ...yeah. This is where it gets a
bit tricker. Back in the olden days, when

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you wanted to build a quantum computer, you
needed big things like this. The problem with

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this is that it gets a bit hot, and we maybe
knock something, and it all misaligns. What

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we do in Bristol is we've been designing and
fabricating what we call waveguides. Now waveguides

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are basically just bits of fibre-optic on
chip, on a bit of glass.

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TOM: Okay.

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JACQUES: So we can actually manipulate the
photons moving through a bit of silicon.

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TOM: And so by changing how the waveguides
act, you can change the photons --

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the way the photons pass through the system.

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JACQUES: Exactly.

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TOM: And that's your programming? That's algorithm
design...

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JACQUES: That's our programming. So we're
going to get our bit of glass, and we're going

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to put a metal piece of conductor on top.
And when we apply a voltage, it's going to

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heat the thing up -- it's a heater...

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TOM: Which changes how the waveguide acts...

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JACQUES: Yeah! It changes the refractive index.

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TOM: Which slows the light down.

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JACQUES: Precisely.

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TOM: Just a tiny amount but enough to change
the interference pattern later on, because

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we're dealing with the speed of light, the
wavelengths involved are tiny tiny tiny...

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JACQUES: Yes, exactly.

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TOM: So a tiny bit of heating in the waveguide
changes the interference pattern, changes

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the quantum computer, that's your programming.

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JACQUES: You got it. You got it!

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TOM: There is a guy -- the person from the
university who's just behind the camera, who

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you can't see in the dark there, is just going
"yes! he got it!"

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JACQUES: It's online now. So what you can
do is, you can go and play around with a simulation

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of it, a model, and if you come up with an
idea you can then ask to actually use it.

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TOM: To use that?

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JACQUES: And to put photons into it and to
heat it up in real life. So it's there, for

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people to use, it's called Quantum in the
Cloud.

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That's what we're getting excited about.

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TOM: Jacques Carolan is from the Centre for
Quantum Photonics at the University of Bristol.

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Jacques, thank you very much.

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JACQUES: Thank you very much, Tom.