Computeractive – 6 January 2016

What’s All the Fuss About...
Quantum dots
Einstein wouldn’t have liked it, but scientists say they have created
an internet that’s impossible to hack
What are they?
Semiconductor crystals so mindbogglingly
small - between two and 10
nanometres (10 to 50 atoms in diameter)
- that they start behaving very oddly.
How oddly?
So oddly that even Albert Einstein
refused to believe it was possible (he
described the phenomenon as “spooky”).
Here’s a quick lesson in quantum
physics. In this subatomic world very
weird things happen. One of the
weirdest is that particles can be
connected by a mysterious force even
if they are separated by vast distances.
In this process – called quantum
entanglement – one particle can affect
how another behaves. For example, if
one particle spins clockwise, its partner
will spin counter-clockwise.
A team of scientists based at the
universities of Glasgow, Stanford, Tokyo
and Würzburg recently demonstrated
how these connected particles can be
used to encrypt data that becomes
impossible to hack when sent over
the internet.
Are you sure hackers couldn’t
fi nd a way?
Only if they altered the laws of physics by
stopping particles affecting each other.
Hackers are clever, but not that clever.
What did the scientists
actually do?
Just the sort of everyday task we all
perform: they ‘entangled’ the spin of
an electron stored in a quantum dot
with a single photon that was sent
across two kilometres of standard
fi bre-optic cable. Next, they encoded
information in these particles in the
form of qubits, which are the quantum
equivalent of binary bits - ones and
zeroes - in conventional computing.
Because these particles are linked, any
attempt by hackers to intercept the data
would change its properties, making the
Caption
attack easy to spot. Furthermore, the
information is impossible to copy
because at the quantum level particles
exist in all possible states until they are
observed or measured (the famous
Schrödinger’s cat paradox). By observing
the data, hackers would fundamentally
change it, making it useless to them.
Doesn’t this require
specialised equipment?
Not anymore. What’s important about
the recent experiment is that it shows
how information can be sent on standard
fi bre-optic cables - the type already
used worldwide. Th e scientists who
conducted the research claim that the
technology could be commonly used
by communications companies “in the
near future”.
Quantum dots - as seen in these dials - can be
used to produce better screen quality on TVs
Can quantum dots be used
for anything else?
Yes, and if you’ve got a Kindle Fire tablet,
you may have seen what they can do
- which is to emit light that produces
brighter, more precise colours than was
previously possible. Amazon built
quantum dots into the HDX 7 and 8.9
models of its tablet, while Sony, Samsung
and LG have all made LED TVs with them.
Th ese work by sitting on top of the
backlight layer on screens in order to
produce richer whites that contain all the
colours of the spectrum. Th e results are
images that look more realistic than ever.
What’s that got to do with
internet security?
Nothing. Th e potential for quantum
dots to improve encryption has only
recently been taken seriously. Another
use could be to make phones and
tablets charge faster. In November,
researchers at Vanderbilt University in
Nashville said they made quantum dots
out of iron pyrite - also known as fool’s
gold - that could fully charge devices in
just 30 seconds. Not bad for an object
that’s 10,000 times narrower than a
human hair.
6 – 19 January 2016 49