The coherent photon-subtracted two-mode squeezed thermal states (CPS-TMSTS) are theoretically introduced by successively performing coherent photon subtraction operation on the two-mode squeezed thermal states (TMSTS). Based upon the normalization factor which is related to bivariate Hermite polynomials, the nonclassicality and non-Gaussianity are analyzed according to the Wigner function. It is shown that the coherent photon subtraction operation is an effective manner in generating nonclassicality and non-Gaussianity. Furthermore, the fidelity in teleporting coherent states using CPS-TMSTS as entangled resources is quantified both analytically and numerically. It is shown that the quantities of fidelity are clearly larger than that in the original TMSTS, and it can be further improved by modulating control parameters effectively. The CPS-TMSTS, as the ideal entangled resources with higher quantum teleportation fidelity, shall have potential applications in quantum optics tasks.

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A scheme is proposed to investigate the non-classical states generated by quantum scissors device (QSD) operating on the the cavity mode of optomechanical system. When the catalytic QSD acting on the cavity mode of optomechanical system, the resulting state contains only the vacuum, single-photon and two-photon states depending upon the coupling parameter of optomechanical system as well as the transmission coefficients of beam splitters. Especially, the output state is just a class of multicomponent cat state truncations at time t = 2π by choosing the appropriate value of coupling parameter. We have discussed the success probability of such state and the fidelity between the output state and input state via QSD. Then the linear entropy is used to investigate the entanglement between the two subsystems, which finds that QSD operation can enhance their entanglement degree. Further-more, we also derive the analytical expression of Wigner function (WF) for the cavity mode via QSD and numerically discuss the WF distribution in phase space at time t = 2π. These results show that the high non-classicality of output state can always be achieved by modulating the coupling parameter of optomechanical system as well as the transmittance of beam splitters.

Nonlinear phase measurement plays an important role in many dynamic processes. In this paper, we propose a single-mode measurement scheme for second-order nonlinear phase shifts that utilizes coherent states and homodyne measurement. The sensitivity at operating point φ = 0 is 1 / 4 N 3 / 2 with N photons on average and approaches the quantum Cramér–Rao bound. In addition, sensitivity with a small value of φ is discussed. For practical purposes, we analyze the effects of photon losses, thermal photon noise, and phase diffusion on sensitivities with φ = 0 as well as a small value of φ . The sensitivity still scales as 1 / N 3 / 2 in the presence of photon losses and thermal photon noise but degrades to the scaling of 1 / N with phase diffusion.