Save light in record-capacity memory

A team of scientists from the University of Warsaw’s Center for New Technologies is working on a device that will remember light and store it in quantum memory. So-called. multimode quantum memory based on cold rubidium atoms could come in handy m.in. in safe communication.

In research at the Quantum Memory Laboratory led by Dr. Parniak. Wojciech Wasilewski has been involved from the very beginning with Dr. Michal Parniak – a researcher of the wyroawarded by the Foundation for Polish Science in this year’s edition of the START scholarship program.

– We started with the construction of an experimental setup, allowing us to obtain one of the longest cold clouds of atomicoin the world. Such an arrangement makes it possible to obtain a high optical density, whichora directly translates into memory performance – mowi Dr. Parniak.

FNP scholar explains that laser cooling stops excessive atom movementoin whichory normally leads to the loss of stored quantum information. Rubidium is a metal, but when heated it evaporates. In this gas atomow can save light. However, for accuracy at the level of single photonoThe gas must be cooled. Atoms are cooled by laser beams to a very low temperature: 20 millionths of a degree above absolute zero.

Tame single photons

The next stage of work in the laboratory was proto control single photonoIn the cloud stored atomow, or in quantum memory. – With a camera sensitive to single photons, we were able to observe photon emissionsow of the cloud under many roThe research will also examine how the loss of the recorded data. This feature is what makes our memory multi-mode, allowing us to store and generate multiple photonow simultaneously – mowi scientist.

Researchers decided to manipulate the stored photonow. In this record-breaking memory, they take the form of so-called spin waves. As Dr. Parniak points out, the ability to manipulate spin waves provides an important bridge between row different approaches to quantum computing. Quantum processors based on superconducting circuits are developing rapidly (e.g. IBM), but difficulties are posed by the transmission of qubitoin between them. On the other hand, scientists are able to transmit single photons over long distances, but it is difficult to process them.

– Our spin wave processor, in whichohe interference between two single waves that we have been able to show so far may allow us to solve these problems, since we already know how to easily convert spin waves into photons and vice versa, he assures wyrosion winner of START grant.

Dr. Parniak points out that creating such a device, in which theorym could save light is a great challenge for quantum physics. Fromod applications that can be imagined is the use of the „caught” photon to secure data. Information in whichorych 1-quantum bit would be stored in a single photon, could not be approached without the knowledge of the participantsoin communication. No one moThis is because if only part of the message were overheard, the signal would simply stop being received.

Dr. Parniak is interning in Copenhagen and has worked in Silicon Valley and Hong Kong. Physicist stresses importance of wsporesearch collaboration with Chinese groups thatore working on solving similar problemsow.

Sourceosource: PAP – Science in Poland, photo. NASA Goddard Space Flight Center/ CC BY 2.0/ Flickr