This paper demonstrates a scheme that combines a linear quantum scissor (LQS) with weak cross-Kerr nonlinearity (CKN) to perform quantum nondemolition (QND) measurements. Performing the postselection on an input coherent state in the LQS, a superposition of vacuum and a single-photon component is truncated. The truncated state is coupled with a Fock state $|N\rangle$, via the CKN. The combination provides more flexibility for generating a nonclassical phase-labeled truncated state (PLTS). The phase shift of the PLTS is proportional to the photon number $N$. Here, we examine the nonclassical properties of the PLTS. By applying beam-splitter interference and detecting the outputs, the QND measurement of the photon number takes place. In this approach, the photon-number information which is imprinted as a phase shift on the PLTS is converted into detectable intensity differences between output ports. For low-photon-number regimes, the scheme outperforms the conventional coherent-state-based QND scheme due to the non-Gaussian nature of the PLTS, which reduces phase diffusion and increases the visibility of interference fringes. Thus, the scheme offers a clear advantage in realistic, low-photon-number conditions, particularly in weakly nonlinear media, where the conventional coherent-state-based QND scheme faces limitations. However, the non-Gaussian features of the PLTS still provide unique advantages in terms of heralding and robustness to experimental imperfections.

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• Quantum measurements
• Quantum nondemolition measurement