Ntt Co Team Proposes Half-Beam Splitter Protocol for Rotation-Symmetric Cat Bell State Measurement

Scientists Issa Oe of NTT in Japan and colleagues have achieved a deterministic Bell state measurement (BSM) for rotation-symmetric cat codes under ideal conditions, utilising an arbitrary symmetry order N. The team developed a protocol employing only a half beam splitter and photon-number-resolving detectors. This method extracts both photon-number modulo and phase information, exceeding previous techniques that required more complex nonlinear operations and identifying a loss regime where higher-order codes offer advantages. The work simplifies the process of measuring quantum states using rotation-symmetric cat codes, a technique for encoding and transmitting quantum information, and represents a significant advancement in the field of quantum information science. This method requires fewer complex operations than previous…