Quandela makes over 1,000 spin-photon interfaces on a pilot production line

[ShadowRider91]

French quantum company Quandela, working with the C2N nanoscience centre and several universities, has shown it can fabricate more than 1,000 spin-photon interfaces on a foundry compatible semiconductor production line. That might not sound thrilling, but it is a big step for the field. Most quantum hardware results so far have come from what researchers call hero devices, a handful of carefully made samples that work brilliantly but cannot be reproduced at scale

A spin-photon interface is a small semiconductor structure that links a stationary qubit, stored in the spin of an electron, with photons that can carry that information elsewhere. The idea is that spins act as memory while photons move data around a network or between processors. That hybrid approach is one of the more promising routes to building larger quantum computers

The performance numbers are solid across the batch, not just in one lucky device. The team achieved seven-partite entanglement, with one spin entangled with six photons, and a spin-photon entangling fidelity of 93.5 percent. Photon indistinguishability averaged 95 percent and reached 98 percent in the best devices. Extraction efficiency was 80 percent, and spin coherence stretched to 1.94 microseconds, about two orders of magnitude better than before

The researchers put it neatly, saying the challenge is shifting from proving the spin-photon interface works to optimising and integrating it. That is what maturity looks like in any technology. You stop asking whether something is possible and start asking how to make lots of it reliably. The work is currently a preprint on arXiv with collaborators from France, Singapore, Denmark, Germany and Italy

This comes a day after we discussed Pasqal stepping back from a French defence programme, so France is clearly having a busy week in quantum. Do you think manufacturing is now the real bottleneck for quantum computing, more than the physics? And is 93.5 percent fidelity good enough to build on?

Quandela Builds Thousands Of Spin-photon Interfaces For Hybrid Quantum Computingquantumzeitgeist.com