The blog of Xeno, a slightly mad scientist
It turns out that the fastest known thing in the universe, light, can in fact be stopped. A German team of scientists have successfully stopped light from traveling for a whole minute. The record-breaking event could be a major breakthrough in the field of quantum memory storage.
So how did scientists freeze light for a whole minute, knowing that the speed of this electromagnetic radiation is 300 million meters per second? In one minute, light can actually travel 18 million kilometers (11 million miles), which makes the research team’s feat even more impressive.
The team at University of Darmstadt, led by George Heinze, pulled it off by using a process named electromagnetically induced transparency or EIT. More specifically, they used a quantum interference effect to turn an opaque medium transparent.
During the experiment, the German scientists shot a laser beam through the crystal, sending the atoms into a quantum superimposition of states and making it transparent. A second laser beam was then shot into the crystal, and the first beam was turned off, which consequently switched off the transparency. The result was that the second beam of light was trapped in the crystal for a whole minute.
The researchers also used the opportunity to successfully store and retrieve information from the light beam: a 100 micrometer picture of three horizontal stripes. This further proves that it is possible to imprint information on light beams, an essential step for quantum information processing.
Time of storage however depends on the superposition of the crystal, which can be extended with a magnetic field, but this also complicates the laser configuration. In order to trap light for one minute, the German team designed a specific algorithm to find the best laser and magnet combination for their experiment.
This is not the first time scientists freeze light successfully. The first experiment was conducted in 1999, when physicists slowed light down to 17 meters per second. In 2001, the University of Darmstadt team froze light for a fraction of a second and earlier this year, Georgia Institute of Technology researchers managed to keep it still for a total of 16 seconds, with the help of cold atoms.