Researchers achieve record quantum entanglement with 14 photons at once

Researchers at the Max Planck Institute of Quantum Optics set a new record after achieving a quantum entanglement of 14 photons, the largest on record so far, an institutional press release said.

Quantum entanglement, famously described by Albery Einstein as "spooky action at a distance" is a phenomenon where particles become intertwined in such a way that they cease to exist individually, and changing the specific property of one results in an instant change of its partner, even if it is far away.

Even though science fails to explain this, experiments successfully demonstrate that quantum entanglement exists and has now even become the basis of upcoming technologies like quantum computing, where entangled particles are used to store and process information. Following computing parlance, these are called quantum bits or qubits.

Quantum entangling photons

Scientists have previously managed to entangle trillions of atoms of gas. While this might be useful to demonstrate the phenomenon, it cannot be used for purposes of computing where a more controlled entanglement is required.

Researchers at the Max Planck Institute of Quantum Optics, therefore, set about to achieve this. They placed a single rubidium atom in an optical cavity so that it be bombarded with light particles and bounce off electromagnetic waves. When the atom was struck by a laser at a particular frequency, it prepared it to have a certain property. Then a separate control pulse was beamed at it, which caused it to emit a photon that was entangled with the atom.

The process was then repeated until a whole chain of photons was produced that were all entangled with each other. Between each emission, the atom was rotated which helped in the entangling of the 14 photons, the press release said.

The researchers claim not only claim that this is the largest number of photons entangled with an atom in a laboratory but also that it is the most efficient process developed so far, with a 43 percent source-to-detection efficiency.

In plain speak, it means that for every second push of the button to fire a laser, the researchers were able to generate, one photon of light that could be used for a specific application. This has solved the long-standing obstacle on the path of scalable, measurement-based quantum computing, the researchers claim.

Where will this help?

The quantum entanglement of 14 photons generated using this method may seem too low when compared to other methods. However, photons created on those methods are generated randomly and cannot be bundled. Since a single atom was used by the researchers in this method, they can produce photons in a highly deterministic way, which is necessary for quantum applications.

Apart from quantum computing, the research can also help in advancing quantum communication, where information sent through optic fiber won't be prone to tapping. The method developed by the researchers will allow quantum information to be sent over entangled photons, which will not only survive certain amounts of light loss but also secure communication, the press release said.

The researchers are now working to generate photons from two atoms to take their work forward.

The results of the study were published in the journal Nature.