Optomagnomechanical mass sensor enhanced by higher-order exceptional point

In non-Hermitian physics, exceptional points (EPs) hold great potential for quantum technologies, while optomagnomechanical (OMM) systems offer a versatile platform for exploring such effects. Here, we propose a third-order EP-enhanced OMM mass sensor, where the eigenfrequency evolution of the system is directly mapped to the optical cavity output spectrum. We demonstrate that the third-order EP delivers a strongly enhanced eigenfrequency response to tiny mass perturbations, achieving over two orders of magnitude higher frequency sensitivity than conventional EP-free OMM systems, without requiring strong optomagnomechanical coupling or high-intensity driving. The sensing mechanism relies on mass-induced mechanical frequency shifts that lift the EP degeneracy and split eigenfrequencies, enabling high-sensitivity detection via the linear scaling between the cube of the eigenfrequency shift and target adsorbed mass. Spectral analysis confirms optimal measured spectral resolution (MSR) at the EP under gain-dissipation balance, with the performance enhancement originating from the intrinsic properties of the third-order EP rather than cavity gain. This scheme breaks the sensitivity bottleneck of traditional OMM sensors, paving the way for ultrasensitive nanoparticle detection and quantum metrology.