Identifying W states—a special form of multi-photon entanglement—has resisted physicists for a quarter century. Researchers now report that they have developed and experimentally demonstrated a method that does exactly that, solving a long-standing measurement challenge.
W states are considered important for quantum information processing, but they are notoriously hard to measure. The new technique could make complex entangled systems much easier to analyze, potentially opening up fresh possibilities for quantum teleportation and related applications.
The report is based on a single source, so there are no conflicting findings to compare. The authors describe the work as a breakthrough, but independent verification and further details would be needed to assess the full scope of the advance.