Two particles of light can 'sync up' their behavior without ever actually meeting or being in the same place.
April 14, 2026
Original Paper
The non-local Hong-Ou-Mandel effect
arXiv · 2604.10886
The Takeaway
This demonstration of a non-local Hong-Ou-Mandel effect proves that quantum interference doesn't require particles to physically cross paths at a beam splitter. It shows that quantum correlations are a property of the paths themselves, enabling new ways to build quantum internet nodes.
From the abstract
Two-photon interference effects arise because photons are indistinguishable particles. In the wellknown Hong-Ou-Mandel (HOM) effect, the transmission of two photons at a beam splitter interferes destructively with the reflection of both photons, requiring both photons to "bunch up" by leaving the beam splitter on the same side. Here, we show that the interference between locally propagating photons and photons exchanged by a mode swap can be implemented by post-selecting spatially separated phot