Researchers from Vienna have succeeded in carrying out a strong interaction between two photons using a system of ultra-thin glass fibers. The groundbreaking development could open new possibilities in quantum technology.

The idea that interaction between two photons doesn't usually occur in free space supports the fact that light waves pass through each other without influencing each other at all.

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Current technology uses non-linear media to make light waves interact with each other. This method creates indirect photon coupling where light can affect the material's properties and the material, as well influencing light.

The downside to the use of this method, however, is that strong light intensities are required, allowing many photons to take part in the process.

In the new system developed at the Vienna University of Technology (TU Wien), the interaction occurs only between two photons by using the smallest possible intensity of light to achieve the strongest interaction.

The interaction is strong enough to change the phase of the photons by 180 degrees.

Professor Arno Rauschenbeutel from the Institute of Atomic and Subatomic Physics in TU Wien described the process as a pendulum, which typically swings to the left, but because of the presence of coupling in the second pendulum, it swings to the right instead.

To make the system work, researchers coupled a very thin glass fiber with a "bottle-like" optical resonator. This allows light to enter the resonator, move in circles and then return to the glass fiber.

The sequence inverted the phase of the photon. In order to maintain the phase shift and to prevent light from entering the resonator, the researchers paired a single rubidium atom to the resonator.

In addition, when two photons arrive simultaneously, a photon can be absorbed in a short time while the others can still be phase shifted. This is a completely different behavior than that seen in single photons.

"That way, a maximally entangled photon state can be created," noted Rauschenbeutel. "Such states are required in all fields of quantum optics -- in quantum teleportation, or for light-transistors which could potentially be used for quantum computing."

The study, which demonstrates how photon interaction occurs in a fiber system, was published recently in the journal, Nature Photonics.

TagsPhotons, Light Waves, Photon Interaction, quantum mechanics, Quantum technology, Quantum computing, Nature Photonics