Nanostructured surfaces for future quantum computer chips

Nanostructured surfaces for future quantum computer chips

Researchers at Paderborn University have developed a new technology for manipulating light that can be used as a basis for future optical quantum computers.

New optical elements for manipulating light will allow for more advanced applications in modern information technology, particularly in quantum computers. However, a major challenge that remains is non-reciprocal light propagation through nanostructured surfaces, where these surfaces have been manipulated at a tiny scale.

Non-reciprocity is a special characteristic in optics that causes light to produce different material characteristics when its direction is reversed. One example would be a window made of glass that is transparent from one side and lets light through, but which acts as a mirror on the other side and reflects the light. This is known as duality.

The researchers combined non-reciprocal light propagation with a frequency conversion of laser light, in other words a change in the frequency and thus also the colour of the light.

In their first experiments, the intensity of the frequency-converted light within the visible range was still very small. The next step, therefore, is to further improve efficiency so that less infrared light is needed for the frequency conversion. In future optically integrated circuits, the direction control for the frequency conversion could be used to switch light directly with a different light, or to produce specific photon conditions for quantum-optical calculations directly on a small chip.

The work has been published in the journal Nature Photonics.

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