When photons meet: a step toward the quantum computer published in Nature Communications

These interactions are essential for exploring new states of light and creating more complex quantum optical systems. In the context of quantum computing, they could enable the design of more sophisticated photonic logic gates capable of performing calculations that are currently impossible with conventional computers.

The challenge faced by the researchers was twofold:

1. Manufacturing the device: KITE measures only a few micrometers and incorporates around a hundred Josephson junctions. Its production required high-precision electron lithography.
2. Detecting interactions: using spectroscopy, the researchers were able to observe frequency variations when photons were introduced successively, proving that they interact strongly.

We observed a previously unknown pattern: to introduce a second photon, then a third and a fourth, sometimes the frequency had to increase, sometimes it had to decrease, and the amplitudes were much greater than in conventional systems. This proves that the interactions between photons were much stronger than those obtained so far!

Zaki Leghtas, researcher at Mines Paris – PSL

Although this breakthrough is a “digression” from their initial goal—the design of a protected qubit—it provides a solid foundation for further research on superconducting circuits and next-generation quantum computers.

The full interview with Zaki Leghtas on the Inria website:

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Further reading

• Extended control of cat qubits: a breakthrough in quantum computing published in Nature
• Antoine Tilloy analyzes tensor networks in relation to quantum computers in the magazine Pour la Science

Read the article in Nature Communications