Fundamental limitations of sensitivity of whispering gallery mode gyroscopes

We analyze theoretically both the fundamental and the technical quantum limitations of the sensitivity of a passive resonant optical gyroscope based on a high finesse monolithic optical microcavity. We show that the quantum back action associated with the resonantly enhanced optical cross- and self-phase modulation results in the standard quantum limit of the angle random walk of the gyroscope, which reaches approximately 0.2 deg/hr1/2 for a millimeter scale CaF2 whispering gallery mode resonator based device.