The ultimate limit of phase sensitivity Δ φ QCRB of an MZI with the PS-TMSVS. (a) The Δ φ QCRB as a function of the initial squeezing parameter z for some values of (k,l); (b) The Δ φ QCRB varies with the total mean photon number for some values of (k,l). The upper black line denotes the SNL limit, while the below black dashed line represents the HL limit.