If you are among the group of people who either are really into quantum physics, or people
who have used a computer, there's some big news this week. But it took place on
a very small scale. researchers at the University of New South Wales in Sydney,
have just created a kind of quantum logic circuit out of silicon, clearing
the way for actual -were not just talking about the many- where we can actually
build one now: quantum computers. Quantum computers are exciting because they
could carry out multiple computations at once. This won't make browsing the internet
any faster, but it will, for example, let drug companies test all of the possible
outcomes of different chemical combinations at the same time, which
could make discovering new drug treatments exponentially faster. But how
would a computer like that work? Well, the fundamentals would be kind of the same as they are now.
The computer or phone or tablet you're using right now
renders data in binary bits. Bits are binary because they can only be in one
of two states; one or zero. So if you have two bits they can be in any of the
following positions. 00 01 11 or 10. Those are all of the four combinations you can
make out of two bits. But while each bit can be in any of those positions, they're
only in one of them at a time. In a quantum computer, two bits
could be in all four of those positions at once. Now! how in the name of Schrodingers cat,
is that possible?
well if you've ever heard of doctor Schrodingers's famous thought experiment,
the same logic that applies to the cat, applies here. In conventional computers,
bits are encoded by circuits that are either on or off, 1 or 0, by using an
electrical current, which is just a flow of electrons. But quantum computers could use
quantum bits called qubits, by using a single electron. And unlike a digital
circuit an electron can be doing all sorts of things at once.
A single-electron for example might either be spinning in alignment with the
nearest magnetic field or spinning perpendicular to it. But until you measure
the electron, it's actually doing both at the same time. It doesn't have a defined
state. This is called quantum superposition. Now, you still have to
measure this spin to get a value for that qubit, so you're still going to get a 1 or a 0.
But by measuring it in parallel, you can get multiple values for a single qubit
at the same time. So with two qubits wired together you could get four values
and if you have three qubits you can have eight, and so on. But guess what?
Making actual circuits with qubits is incredibly hard. What the New South Wales
team managed to do is build on all of these ideas to create a quantum logic gate.
qubits that could interact with each other. logic gates are the basis of any
digital circuit, they take data from bits apply programmed logic, to the
information and then output new data based on the results. So the team took
the existing technology in a silicon microchip, and reinvented its transistor.
The tiny switch that turns off and on to create ones and zeros. But instead of being
controlled by a current or a flow of electrons, each transistor basically
trapped a single electron and stored it spins as information. They then use
microwaves and electrodes in the chip, to change the spin of one electron, and
therefore the information in that qubit. That information then change the state of the
qubit that it was connected to. The result was a sort of quantum if/then
command, where the state of 1 qubit depended on the state of the other.
The researchers have worked out how to scale up this design from two qubits, to hundreds
or potentially millions. And they've patented this design based on the same
manufacturing methods that are used to make microchips today. So quantum physics
is weird, but quantum computing would be amazing. Thank you for watching this sci-show news,
brought to you by Audible, which is giving away free audiobook to sci-show
viewers. Check out audible.com/scishow where you can download books like the
pleasure of finding things out, the best short works of Richard P Fineman or
practically any other book for free.
go to audible.com/scishow
to learn more.