Physicists at the University of New South Wales have created a transistor composed of a single atom, which is an amazing feat of nanoengineering, and could provide a better foundation for scalable quantum computing. The technique and experiment have been published in Nature Nanotechnology.
The transistor itself is
composed of a single phosphorous-31 isotope, which has been precisely
placed on a base of silicon using a Scanning Tunneling Microscope in an
ultra-high vacuum chamber. What’s particularly amazing about their
technique is that they were able to position the individual phosphorous
atoms precisely. The atom was confirmed to be exactly where it needed
to be. Considering that most single-atom devices have a positioning
margin of error of about 10 nm, that’s an impressive accomplishment.
“Our group has proved that it is
really possible to position one phosphorus atom in a silicon
environment – exactly as we need it – with near-atomic precision, and
at the same time register gates,” said lead researcher Dr. Martin
Fuechsle in a press release.
Some physicists have conjectured
that the two possible nuclear spins of P-31 make it ideal for use as
the basis for solid-state quantum computing. That’s especially true
because if phosphorous and silicon are used, it’s conceivable that
techniques used are compatible with CMOS systems used in today’s
computers.
Despite the small size
of the transistor, the team was able to confirm that the electrodes
present on the silicon were contacting the transistor, and also
confirmed that they were able to successfully change the quantum states
of the atom – which means that it can be successfully used as a
transistor.
As amazing an achievement as
this is, this is only the start of providing a basis for either
conventional or quantum computing. Researchers will need to build off
of this technology to develop chips comprised of many P-31 transistors
that are able to be used for computation. Even once that’s achieved,
we’re still a long way from using chips based on this transistor in
your home. Scanning Tunneling Microscopy is a pretty powerful tool for
positioning individual atoms, but it’s also incredibly expensive to use
as a basis for manufacturing.
That said, I’m very excited
about the trend of potential quantum computing that uses cheap
materials, such as silicon and phosphorous, as a base for materials.
From an economic standpoint, that obviously has some advantages over
more expensive materials such as superconductors or diamonds, which
have been used in other quantum computation applications. It’ll be
interesting to see how this develops over the next few years.
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