University of Pennsylvania-led team moves a photonic quantum skyrmion onto a two-photon entangled state on a chip

Photonic Inc.

A team led by the University of Pennsylvania showed that a quantum skyrmion, a light pattern with a topological count, can be prepared and transferred on a silicon nitride nanophotonic chip. The structure moves from one photon to a shared two-photon entangled state, which the authors propose as a noise-tolerant link for distributed quantum computing. The work appears in Nature Physics.

• Entangled photon pairs are generated by four-wave mixing in 650 nm wide silicon nitride spiral waveguides.
• Spin-orbit-locked microring resonators encode the skyrmion on one photon; an on-chip Bell measurement transfers it to the shared two-photon state.
• The measured skyrmion number is 1.981 ± 0.002 before transfer and 1.981 ± 0.001 after, close to the ideal value of 2.
• Pure-state quantum fidelity is 89% ± 2%.
• The optical-interconnect use is a proposed blueprint, not a demonstrated system; the article does not say whether the noise tests were run on hardware or in simulation.