A team of researchers from the University of St Andrews and
the University of York has slowed down the speed of light in a process which
could have major applications in fundamental science and medical diagnosis.
Dr Yoshihiko Arita and Professor Kishan Dholakia of the
School of Physics and Astronomy at the University of St Andrews and Dr Mark
Scullion and Professor Thomas Krauss of the University of York created a
specially fabricated nanostructure and used it to drive particles at high speed
along a track of light.
The work, published in the international journal Optica,
could open up more rapid methods of understanding disease or indeed the way we
look at the biological world in general.
As light bends through a transparent object such as a
marble, it exerts a minuscule but important force. The marble could not move as
the force is too weak, but the force is sufficient to move and propel particles
the size of blood cells or smaller.
Light moves at 186,000 miles per second but can be slowed
down in glass, for example, by a third.
The researchers designed special nanostructures made from
silicon that affect the motion of photons, called photonic crystals, to reduce
the speed further.
The effect is like placing speed bumps into the light’s
path, and the researchers managed to slow the light down by 95%, corresponding
to a reduction by a factor 20 compared to free space.