Quantum move toward next generation computing
McGill researchers make important contribution to the
development of quantum computing
Physicists at McGill University have developed a system for
measuring the energy involved in adding electrons to semi-conductor
nanocrystals, also known as quantum dots – a technology that may
revolutionize computing and other areas of science. Dr. Peter
Grütter, McGill’s Associate Dean of Research and Graduate
Education, Faculty of Science, explains that his research team has
developed a cantilever force sensor that enables individual
electrons to be removed and added to a quantum dot and the energy
involved in the operation to be measured.
Being able to measure the energy at such infinitesimal levels is an
important step in being able to develop an eventual replacement for
the silicon chip in computers – the next generation of computing.
Computers currently work with processors that contain transistors
that are either in an on or off position – conductors and
semi-conductors – while quantum computing would allow processors to
work with multiple states, vastly increasing their speed while
reducing their size even more.
Although the term “quantum leap” is used in everyday language to
connote something very large, the word “quantum” itself actually
means the smallest amount by which certain physical quantities can
change. Knowledge of these energy levels enables scientists to
understand and predict the electronic properties of the nanoscale
systems they are developing.
“We are determining optical and electronic transport properties,”
Grütter said. “This is essential for the development of components
that might replace silicon chips in current computers.”
The electronic principles of nanosystems also determine their
chemical properties, so the team’s research is relevant to making
chemical processes “greener” and more energy efficient. For
example, this technology could be applied to lighting systems, by
using nanoparticles to improving their energy efficiency. “We
expect this method to have many important applications in
fundamental as well as applied research,” said Lynda Cockins of
McGill’s Department of Physics.
The principle of the cantilever sensor sounds relatively simple.
“The cantilever is about 0.5 mm in size (about the thickness of a
thumbnail) and is essentially a simple driven, damped harmonic
oscillator, mathematically equivalent to a child's swing being
pushed,” Grütter explained. “The signal we measure is the damping
of the cantilever, the equivalent to how hard I have to push the
kid on the swing so that she maintains a constant height, or what I
would call the ‘oscillation amplitude.’ ”
Dr. Yoichi Miyahara, Aashish Clerk and Steven D. Bennett of
McGill’s Dept. of Physics, and scientists at the Institute for
Microstructural Sciences of the National Research Council of Canada
contributed to this research, which was published online late
yesterday afternoon in the Proceedings of the National Academy of
Sciences. The research received funding from the Natural Sciences
and Engineering Research Council of Canada, le Fonds Québécois de
le Recherche sur la Nature et les Technologies, the Carl Reinhardt
Fellowship, and the Canadian Institute for Advanced Research.
This image shows the electrostatic energy given off when electrons
are added to a quantum dot. It was created with an atomic-force
microscope. Photo Credit: Dept. of Physics, McGill University.