Scientists managed to "freeze" light rays for a whole minute

In what could be a major breakthrough in the fields of quantum memory storage and information processing, German researchers have managed to freeze the fastest thing on earth: light. And not only that - they managed to do it for a whole minute.

In what could be a major breakthrough in the fields of quantum memory storage and information processing, German researchers have managed to freeze the fastest thing on earth: light. And not only that - they managed to do it for a whole minute.

The reason why scientists are interested in "holding" the light in its place is to ensure that it preserves its quantum coherence properties (that is, the information state in it) and thus use it to develop a light-based quantum memory. And the longer the state of light can be kept stable for a longer time, the more efficient the state will be in terms of its usefulness for quantum computing. As a result, it will be possible to use more secure quantum communication over longer distances.

It goes without saying that stopping the light is no small task - you can't just put it in the freezer. The light rays are electromagnetic radiation that moves at a speed of 300 million meters per second. For example, for a full minute, light is able to travel 18 million km, a distance equal to the distance of 20 trips to the moon. At the same time, the speed of light can be slowed down and even stopped completely. In fact, researchers have already managed to stop the light for 16 seconds with the help of cold atoms. (Link to the abstract of the article).

In the current study, scientist Georg Heinze and his research team converted optical coherence to atomic coherence. They were able to do so with the help of a quantum effect that transforms an opaque medium - in this case a crystal - into a medium that is transparent to a narrow spectrum of the light spectrum [a process known as electromagnetically induced transparency (EIT)].

The researchers aimed a laser beam at a crystal so that the atoms hit by this beam were transferred to a quantum superposition of two states. In the next step, a second beam caused the radiation of the first laser beam to stop, resulting in transparency. In this way the researchers brought about the collapse of the superposition while trapping the laser beam in the crystal itself.

"The new results are six orders of magnitude better than previous experiments carried out with atomic gases and thus offer fascinating possibilities for long-term quantum memory storage. In the next step, the researchers will try to use different materials in order to further increase the storage time of the quantum information. The research findings were published in the scientific journal Physical Review Letters [Article Summary].

The news about the study