Linear optics achieve 9/32 success rate for four-photon entanglement

Stefan N. van den Hoven of the University of Twente and colleagues have achieved a 9/32 success rate for four-photon entanglement using a new family of linear-optical measurements. The work introduces high-efficiency GHZ measurements based on four-mode interferometers, incorporating many-body interference to improve entangling operations. Researchers found that even unsuccessful attempts at entanglement project onto useful stabilizer states, a practical benefit for quantum processing. The results establish high-efficiency many-body measurements as a new primitive for scalable photonic quantum information processing. A 9/32 success rate for entangling four photons using linear optics represents a substantial gain over previous methods, offering a concrete benchmark for efficiency in photonic quantum systems. This achievement stems from a newly developed family of four-mode interferometers designed to perform high-efficiency GHZ measurements, directly addressing a long-standing challenge in scaling up quantum technologies. The design incorporates many-body interference, a key element for unlocking the computational potential inherent in photonic quantum systems, unlike earlier approaches reliant solely on pairwise interactions. The researchers…