The reason Bose-Einstein condensates may prove useful outside the laboratory is that they are to matter what a laser is to light: all their constituent particles march in step.
The way Dr Hau and her team have slowed down light by a factor of 600 million or so is to use a group of atoms called a Bose-Einstein condensate (BEC).
That, at least, was the conclusion of Satyendranath Bose and Albert Einstein, who did the relevant sums in the 1920s, decades before anyone had made a laser, let alone the Bose-Einstein condensate that is named in their honour.
Since they were first made in 1995, Bose-Einstein condensates have become commonplace as experimental tools. (They are particularly valued for their ability to slow the speed of light all the way down to zero.) Dr Steinhauer and his colleagues created a condensate out of a gas of rubidium atoms held in a magnetic trap.