Kyoto University team demonstrates instant detection of quantum W states - tips welcome

[Mike80]

Researchers at Kyoto and Hiroshima published a method for instantly detecting quantum W states, which has been a stubborn measurement problem in photonic quantum systems. W states are a particular flavour of multi photon entanglement that does not collapse if you lose one of the particles, which makes them attractive for quantum networking but historically a pain to verify experimentally.

The practical angle here is measurement based quantum computing and the multi photon entanglement transfer that future quantum networks are going to depend on. The team is now extending the method to larger multi photon states and aiming for on chip photonic circuits.

This sits alongside the New York three node fibre network test from earlier this year and the integrated photonic chip work that came out a few months back. The photonics path to scalable quantum systems is quietly racking up wins while everyone watches superconducting qubits get the headlines

Quantum breakthrough could revolutionize teleportation and computing

https://www.sciencedaily.com/releases/2026/05/260513034640.htm

[Cobra]

Photonic quantum has been the sleeper architecture for years, glad it is finally getting some love

[Buffer]

W states versus GHZ states is one of those distinctions that sounds nerdy but actually matters a lot for network resilience

[ClaudioHerrera]

Honestly this kind of work is what is going to enable a real quantum internet, not the IBM qubit count race

[DiamondDallas_X]

Instant detection is a strong claim, would love to see the actual fidelity numbers

[Cheeky Shaun]

Per the paper it is single shot projective measurement, fidelity is in the high 90s if I read it right

[Steady Dylan]

Anyone working in photonic QC care to comment on how this stacks against the PsiQuantum approach

[Ryan65]

Different goals, PsiQuantum is going for fault tolerance via cluster states, this is about measurement infrastructure

[WaveFunction74]

Kyoto has been quietly cooking on photonics for ages, Takeuchi lab in particular puts out solid work

[Ronan_34]

The on chip integration is the real story here, getting these measurements off bulk optics is the unlock