Scientists have slowed down light inside a vacuum for the first time. By changing the shape of the individual particles in a light beam, they have now proved that light speed in free space is not a constant.
By building a liquid crystal device to alter the shape of individual photons, the physicists worked at the quantum level.
Light travels at an amazing -186,282 miles an hour. Ordinarily, some barrier is needed to slow it down even by a tiny margin. Water and glass work best to illustrate this. But a team of researchers from the Glasgow and Heriot-Watt universities proved that the issue could be approached differently, by using individual photons instead of whole beams.
Not only did they manage to slow down light by using a special ‘mask,’ they managed to keep it moving slowly even after the device was no longer acting upon the photons.
Professor Miles Padgett, Dr Jacquiline Romero, Dr Daniel Giovannini and their teammates working from Glasgow’s laboratory demonstrated their finding by building a sort of ‘race track’ of two photons. They set out to demonstrate how a single photon’s quantum characteristics of both wave and particle can be used to build a special software-controlled device that could alter these functions at will.
The results of their study were published in the journal Science Express on January 23.
The dual racecourse culminated at a light sensor about three feet away, to measure the resulting speeds of two groups of photons. The first group was fired off through empty space unhindered, while the second traveled through the device shaping it into a curved beam. Unlike working with beams from the outset, shaping light in this way proved much more efficient. Individual particles offer greater flexibility.
The software-controlled ‘mask’ slowed down individual photons – an event the researchers compare to a cycling race. If before, we were inclined to measure the average speed of an entire group, we can now make more precise calculations by measuring the speed of a single racer. The group formation always makes it difficult to do that.
The first group of beams reached their destination quicker by a measly 0.001 percent, but that is already a massive implication for physics and the future prospects of working with light.