(Job 18381) Quantum Dynamics
So quantum dynamics is a branch of physics that describes the microscopic world and
what’s so interesting about it is that it behaves completely differently from the
macroscopic or everyday world that we’re used to.
So the everyday world we have an intuition about the laws of physics. If we drop
something it will fall to the ground and smash, but at the microscopic level those sort of
intuitions which we have really don’t apply.
Amazing theories of quantum dynamics
An example of how the quantum or microscopic world is baffling is something called the
Heisenburg Uncertainty Relation. This basically says that it’s impossible to be able to
predict everything about the world, no matter how good we are at measuring it. And
more than that what the theory says is not just that we can’t predict the world, what the
outcomes of our experiments are going to be, but in some sense those outcomes really
don’t exist until we do the experiment. So it’s as if the uncertainty is not just an
uncertainty in our mind, it’s as if nature itself hasn’t made up its mind about what’s going
to happen until we do the experiment. Until we do nature can be in two minds about
things.
The most famous example of this is Schrödinger's cat, which is a thought experiment, so
it’s not a real experiment, no cats get hurt. The idea of Schrödinger's cat is that the cat is
shut in the box and after an hour you look and see whether the cat is alive or dead but it’s
impossible to be able to predict which you’re going to see. But the interesting thing is
that the theory says that not only can you not predict but before you look, in some sense
the cat was neither alive nor dead, it was as if it was both and just didn’t make up its mind
until you looked.
How can we apply this knowledge?
So quantum computing is a great example of how these crazy ideas about the microscope
world can lead to fundamentally new technologies that could transform the way society
works. And really this is just the idea of Schrödinger's cat applied. So the idea is that
you have not a cat being in two uncertain possible states, but a whole computer being in
an uncertain state about what computation it’s doing. Now this might sound like a bad
thing but if you do set things up very carefully what you can have is this so-called
quantum computer being able to do multiple calculations at the same time but in a way
that when you finally come to read it out you just get one answer and it’s an answer that a
normal, everyday computer couldn’t possible compute in a million years.
Another application of the fundamental laws of quantum mechanics is in quantum
communication, and here what’s interesting is that you can actually guarantee unhackable
communication by using the uncertainty principle. So this is actually a technology which
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is commercially available and here at Griffith University we’re working on this as well
with the ultimate goal of building up a global quantum internet.
What sort of work can research students do at the Centre?
In the Centre for Quantum Dynamics we have students doing a wide range of research in
both theory and experiment. As well as a quantum computing and quantum
communication we have students looking at controlling the motion of quantum particles,
atoms, electrons, etc. In particular we have the Australian Nanosecond Science Facility
which lets us look at those motions on an unimaginably short time scale.
One of the great things about research in this area is we have partners all over the world
and in Australia and this is something that makes it a really exciting research area and
keeps our students engaged. So it’s a great environment for PhD students, honour
students and even bright undergraduates. According to John Nash, who is the man who
inspired Beautiful Mind, it was trying to understand quantum physics that actually sent
him mad, so that’s something we hope doesn’t happen with our students.
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