Intracavity squeezing for Kerr QND Measurement scheme
In Ref. [Phys. Rev. A 108, 053708], the scheme of quantum non-demolition measurement of optical quanta that uses a resonantly enhanced Kerr nonlinearity in the optical microresonator, pre-squeezing of the probe beam, and its parametric amplification before the detection, was analyzed theoretically. It was shown that the main factor that limits the sensitivity of the considered scheme is the interplay of optical losses and the non-linear self-phase modulation (SPM) effect. Here we show that using the intracavity squeezing of the probe beam in this scheme, it is possible to cancel out the SPM effect. In this case, the sensitivity will be limited only by the available power in the pump beam and by the input/output losses in the signal beam. Our estimates show, that using the best optical microresonators currently available, the single-photon sensitivity for the intracavity photon number can be achieved. Therefore, this scheme could be of interest for optical quantum information processing tasks.