Progress of the Inertial Mass Measurement Project at NIM

An experiment is proposed to precisely measure the Planck constant. In this experiment, the Planck constant is measured based on the inertial mass measurement rather than the gravitational mass determinations in some other well-known experiments, e.g., the Kibble balance and counting atoms. We link the mechanical force to a quantum-traceable electrostatic force by a beam balance oscillator. After a 5-year continuous effort, the principle of the proposal is verified by a preliminary measurement with a relative uncertainty of 5.4\times 10^-5. The proposal has the potential to achieve much higher measurement accuracy with further improvements.