Physicists transport a entangled state between atoms and photons, Physicists have successfully demonstrated the transport of a entangled state between atoms and photons via optical fiber up to 20 km away, thereby setting a new record.

“Entanglement” describes a very specific type of quantum state that is not assigned to only one particle, but is divided by two different particles.

This irrevocably links their next fate, no matter how far away they are, which is known to have prompted Albert Einstein to describe the phenomenon as a ghostly act in the distance. Attachments have become the foundation of new technologies based on quantum effects, and long distance transmission is the main goal of quantum communication, now the Physicists transport a entangled state between atoms and photons.

Researchers have now shown that entangled states of atoms and photons can be transmitted through glass fibers (such as those used in telecommunications networks) up to 20 km away. The previous record is 700 meters. This experiment is a milestone in the distance traveled asserted that quantum information can be disseminated on a large scale with little loss.

Quantum networks basically consist of quantum memories (for example, one or more atoms) which act as nodes and communication channels through which photons (quanta of light) can spread to connect nodes.

In their experiments, the researchers braided rubidium atoms with photons and discovered the entangled state that now shares the quantum properties of two particles after they cross a 20 kilometer optical fiber coil.

The biggest problem facing researchers is the properties of the rubidium atom. After targeted excitation, these atoms emit photons with a wavelength of 780 nanometers in the region of the near infrared spectrum. “In optical fiber, light is quickly absorbed at this wavelength,” Weinfurtter explained.

As a result, conventional telecommunications networks use wavelengths around 1550 nanometers, which significantly reduces transit losses.

Clearly, this wavelength will also increase the chances of the researchers’ success. Matthias Bock, a member of the Saarbrücken group, built a quantum frequency converter that was developed specifically to increase the wavelength of photons emitted from 780 to 1520 nanometers. The task itself is associated with a number of very challenging technical challenges. It is important to ensure that conversion from only one photon to another occurs and that no other properties of the entangled state, in particular the polarization of the photons, change during the transformation process. If not, the entangled condition will disappear.

By using this highly efficient converter, we were able to maintain a state of entanglement at the wavelength of telecommunications in a much larger area and thus transport quantum information over long distances.

In the next step, the researchers wanted to change the frequency of light emitted by the second atom to create a bond between two atoms in long telecommunication fibers. The properties of fiber optic cables vary depending on factors such as temperature and voltage affected. For this reason, the team intends to carry out this experiment first under controlled conditions in the laboratory.

If successful, a field trial is carried out to add new nodes to the growing network. Because even a long journey can lead to full success step by step.