Nonclassical polarization states of light, switching effect in the Stokes parameters, and the problem of quantum computing for nonlinear distributed feedback systems

摘要

In our paper, we consider a nonclassical behavior of both the polarization Stokes parameters of light and the phase characteristics for two modes that result in the existence of the quantum polarization slates for an optical field. The conditions of formation of polarization-squeezed light in the case of interaction of two orthogonally polarized modes in a nonlinear distributed feedback (DFB) system are discussed. In the general case, we introduce two pairs of the phase operators associated with the phase angles in 3D picture of the Poincare sphere for the polarization Stokes parameters of light. The special eight-port polarization interferometer (polarimeter) is presented for simultaneous homodyne detection of both the Stokes parameters of light and the optical phases difference, and also of their fluctuations. It is shown that a spatio-inhomogeneous optical fiber being placed in the polarization interferometer can be used for generation and detection of the polarization-squeezed phase (PSP) states of light. The analysis of the arising instabilities for two (or four) orthogonally polarized modes in a tunnel-coupled optical fiber (TCOF) has been carried out. New effects of polarization switching are obtained, and we discuss the problem of both the coding of information, and the principles of polarization quantum logical elements in the quantum computing problem. The optical schemes to realize the quantum AND (NOT-AND), OR (NOT-OR) operations, and controlled-NOT gates with quantum nondemolition filtering of the signal, are proposed. [References: 37]