System allowing strong photons’ interaction to be useful in quantum optics

A group of researchers has successfully developed a system using an ultra-thin glass fibre that will allow strong interaction between two photons.

The successful set up for the photons was developed by the researchers at the Vienna University of Technology (TU Wien).

The scientists explain two photons present in free space usually do not interact.

According to the optics experts, interactions between photons are highly crucial in the field of quantum optics. The photon-photon interaction is very important for the creation of quantum information networks as well as the construction of optical logic gates.

The quantum information network enables a secure transmission of data.

Until now, the scientists used non-linear media for the interaction between two light forms. During this method, the light affects the properties of the material, which has an influence on the light.

According to the researchers, this light interaction method carries several drawbacks. One of them is that strong light intensities are required and many photons contribute to the process.

This process results in indirect photon coupling, scientists say.

In the newly built system, the interaction occurs only between two photons and their interface is so strong that it leads the photons to change phase by a complete 180 degrees. For the experiment, the researchers utilized a minimal amount of light to accomplish the highest interaction. A very thin glass fibre was coupled with a small bottle-like light resonator.

This allowed the light to enter the resonator partially and then shift in circles and finally come back to the glass fibre. This results into inversion of the photon’s phase. After this, the researchers coupled a single rubidium atom to the resonator which in turn prevented light from entering the resonator as well as the oscillation phase of photon which could not be changed.

When two photons arrive together, a different process occurs. For a short interval of time, a photon is absorbed by the atom and then releases it into the resonator. As only one photon is absorbed, the other photon gets shifted in other phase.

These photons finally cannot be differentiated from each other. This allows creation of a photon state which can serve very useful in quantum optics, quantum computing and quantum teleportation.

The study was detailed in Nature Photonics journal.

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Christina Langfold

Remember that weird girl in school who never quite managed to fit in? Who was always silent and strange? That was me during my entire teenage life. A few years after finishing college (with a degree in arts) I decided that the best way to become more sociable, while also feeling safe, is to test my people skills online.