In the laboratory of the University of Pennsylvania engineers have created a chip on which quantum skyrmions retain their topological structure even after the complete destruction of photon entanglement. This discovery, published on 30 October 2026 in Nature Physics, shows that topological properties can survive the loss of one of the most fragile quantum connections.
The team led by Liang Feng and with the participation of first author Haoqi Zhao fabricated a miniature chip at the Singh Center for Nanotechnology. On the chip, a pair of entangled photons was generated, after which a characteristic polarization pattern — a quantum skyrmion — was applied to one of them. The researchers then transferred the topological property of this pattern to the joint quantum state of the two photons. When the system was subjected to increasingly strong disturbances, including stray light, the entanglement disappeared, but the defining winding number of polarization states in the skyrmion remained unchanged.
Imagine a vortex in hair: individual strands can be shifted, but the overall pattern and direction of the swirl are preserved. This is exactly how the topological invariant of a skyrmion behaves — it is independent of local perturbations until the critical threshold of destruction is exceeded. Even after the disappearance of entanglement, more general quantum correlations measured via quantum discord were preserved.
This changes the understanding of how to protect information in future quantum networks. Instead of relying solely on fragile entanglement, one can encode data in robust topological patterns that withstand disturbances for longer. The discovery also deepens the understanding of the relationship between topology and quantum correlations in general.
The results obtained on a specially designed chip confirm that topology can exist independently of entanglement, opening the way to more reliable quantum communications and computing.
