By Paul Rincon BBC News Online science staff Physicists say they
have brought light to a complete halt for a fraction of a second
and then sent it on its way. The researchers stopped the light
for a fraction of a second Harvard University staff held a light
pulse still without taking away all of its energy, the journal
Nature reports. Controlling the movement of light particles -
so-called photons - to store and process data could lead to the
development of quantum computers. In a 2001 experiment, light
pulses were briefly stored when particles of light were taken up
by atoms in a gas. The Harvard experiment tops that achievement
by holding light and its energy at a standstill. Light normally
travels at about 299,000 kilometres per second (186,000 miles
per second), but it slows down when passing through some
materials, such as glass. The team fired a light beam called a
signal pulse through a sealed glass cylinder containing a hot
gas containing atoms of the element rubidium, illuminated by a
strong ray of l