Sensitivity enhancement of a dispersive cavity with squeezed vacuum light injection

The measurement sensitivity of a cavity could be enhanced for sensing applications in an anomalous dispersion condition. In this paper, we find that when injecting a squeezed vacuum light into a dispersive cavity, the sensitivity could be improved further, even beating the standard quantum limit at the detuning frequencies via controlling the dispersion condition. It is amazing that normal dispersion is superior to anomalous dispersion in improving the measurement sensitivity in the presence of a squeezed vacuum field. It implies this paper could be used to realize high-precision sensing applications.