Light is incredible. You can bend it, you can bounce it, and researchers have now found a way to trap light, physically move it, and then release it again.
This incredible feat of physics was demonstrated at the Johannes Gutenberg University Mainz and published in Physics Review Letters. Researchers trapped light in a quantum memory, a cloud of ultra-cold rubidium atoms. The quantum memory was then moved 1.2 millimeters and the light was released with little impact on its properties.
"We stored the light by putting it in a suitcase so to speak, only that in our case the suitcase was made of a cloud of cold atoms. We moved this suitcase over a short distance and then took the light out again. This is very interesting not only for physics in general, but also for quantum communication because light is not very easy to 'capture', and if you want to transport it elsewhere in a controlled manner, it usually ends up being lost," senior author Professor Patrick Windpassinger said in a statement.
Quantum communication networks are crucial for the future of computing, which uses the quantum properties of nature as a way to produce incredible computational power. The ability to store and even move light is key to that goal. Without this ability, it would not be possible to scale up a quantum network.
Moving a cloud of atoms is not easy without messing with them. If you want to keep the light trapped within them safe, you need to affect them very little. To solve this, the team developed an “optical conveyer belt.” Two lasers are used to move the cloud of atoms without losing or heating them.
Many obstacles to commercial quantum computers and networks remain but certain barriers were overcome in this work. Quantum systems are susceptible to interference and noise from its surroundings, which is why they are kept at very low temperatures in order to keep the properties of the system under control.
The transport distance is short for now due to several factors, but it boils down to the fact that light can only be stored this way for a limited time. Current storage approaches, like many quantum phenomena, can be disrupted easily. The goal is to keep the light as unaltered as possible. So while 1.2 millimeters might not seem like much, this is a huge step for the field.