Critical States Boost Measurement Precision Beyond Current Quantum Limits

A new framework, criticality-assisted noncommutative preparation (CANP), improves the precision of measurements by utilising critical evolution for state preparation. Ningxin Kong and colleagues at Peking University, in collaboration with Hefei National Laboratory and Shanxi University, developed CANP to overcome limitations in existing methods caused by restricted parameters and operating conditions. The noncommutativity between preparation and encoding operations genuinely enhances the quantum Fisher information, potentially achieving improvements at a fixed sensing time and energy cost. This enhancement, quantified by the Wigner-Yanase skew information, scales similarly to the quantum Fisher information, establishing CANP as a key technique for criticality-enhanced quantum metrology The criticality-assisted noncommutative preparation protocol (CANP) proves effective in the quantum Rabi and Lipkin-Meshkov-Glick models, establishing it…