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Generating Entangled Photons On A Single Chip

 

Entangled photon pairs form the basis of quantum computers and information. The quantum properties of entangled photons allow us to transmit information faster and more efficiently.

However, in order to create this beautiful advantage, some technical problems need to be overcome. Chief among these technical challenges is generating the entangled photons that underpin everything about quantum computers.

Within our current technological capabilities, cumbersome lasers are needed to generate the desired amount of entangled photons and precise procedures for long-term alignment are required and their commercial viability is limited.

A research team at the Leibniz University of Hannover in Germany and the University of Twente in the Netherlands has succeeded in developing a new technology device that can overcome this fundamental problem. In their work, they developed a coin-sized chip that produces entangled photon pairs.

The manufactured chip consists of three main components: a laser; a filter that provides laser stability in a narrow frequency band; and a nonlinear medium that produces entangled photon pairs.

One of the main challenges of the experiment is that the materials used for lasering differ from those required for filtering and entangled pairing, and the manufacturing processes of the two materials are often incompatible.

They worked together with the team of Klaus Boller at the University of Twente to assemble these materials on the chip.

To solve this problem, the team used a technique called hybrid integration. Thus, they were able to combine incompatible materials. The gain medium used for lasering was made of indium phosphide, while the filtering and photon-generating components are made of silicon nitride. They also added an anti-reflective coating to prevent reflection on the interface.

Photons are constrained to travel in micron-wide waveguides printed on the chips.

This chip, which is produced in compact form, is expected to provide a great gain in terms of labor and cost for superconducting and confined atom or ion-based quantum computers, especially photonic-based quantum computers.

The team is now working to expand on-chip photonic capabilities to include the creation of multi-photon cluster states.

If you want to read more about the study, you can reach the article from the reference section.





Reference

Mahmudlu, H., Johanning, R., van Rees, A. et al. Fully on-chip photonic turnkey quantum source for entangled qubit/qudit state generation. Nat. Photon. (2023). https://doi.org/10.1038/s41566-023-01193-1


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