This work discuss the entanglement and quantum polarization of superpositions of two-mode coherent states. We use the concurrence to measure their entanglements and the quantum Stokes parameters and the Q function in order to analyze their polarization and degree of polarization.
Polarization has been used extensively in quantum information processing, and quantum entanglement is essential to many areas of research, including quantum computing. Here we investigate the degree of polarization and the entanglement of a family of quantum states known as photon-added entangled coherent states. Such states could serve as means of entanglement distribution and quantum key distribution. Using the quantum Stokes parameters and the Q function, we demonstrated that, in general, the polarization of a superposition of two two-mode photon-added coherent states increases significantly with the number of added photons. And using the concurrence, we showed that the amount of entanglement in this kind of superposition presents a behavior that is dependent on whether or not the number of added photons on each mode is the same.
Polarization of light has been used extensively in quantum information processing, and quantum entanglement is essential to many areas of research, including quantum computing. Here we investigate the degree of polarization and the entanglement of a family of quantum states known as photon-added entangled coherent states. Such states could serve as means of entanglement distribution and quantum key distribution. Using the quantum Stokes parameters and the Q function, we demonstrate that, in general, the degree of polarization of two two-mode photon-added coherent states increases significantly with the number of added photons. And using the concurrence, we show that the amount of entanglement in this kind of superposition presents a behavior that is dependent on whether or not the number of added photons in each mode is the same.
Polarization has been used extensively in quantum information processing, and quantum entanglement is essential to many areas of research, including quantum computing. Here we investigate the degree of polarization and the entanglement of a family of quantum states known as photon-added entangled coherent states. Such states could serve as means of entanglement distribution and quantum key distribution. Using the quantum Stokes parameters and the Q function, we demonstrated that, in general, the polarization of a superposition of two two-mode photon-added coherent states increases significantly with the number of added photons. And using the concurrence, we showed that the amount of entanglement in this kind of superposition presents a behavior that is dependent on whether or not the number of added photons on each mode is the same.
A brief review of theoretical studies of the quantum state of polarization of light exhibiting the level of fluctuations in at least one of the Stokes parameters which is below the quantum noise limit is presented. Two approaches to generation of polarization-squeezed state of light are analyzed in detail: by propagating coherent radiation in a cubic nonlinear medium and by mixing radiation of two orthogonally polarized quadrature-squeezed modes. The degree of polarization of light is discussed. Other areas of quantum polarization optics, in particular, entanglement of quantum Stokes parameters and quantum polarization tomography, are also discussed.
We present a quantum analysis of two-mode single-photon states based on the probability distributions of the optical field strength (or position quadrature) in order to describe their quantum polarization characteristics, where polarization is understood as a significative confinement of the optical field-strength values on determined regions of the two-mode optical field-strength plane. We will show that the mentioned probability distributions along with the values of quantum Stokes parameters allow us to characterize the polarization of a two-mode single-photon state, in an analogous way to the classical case, and to distinguish conceptually between mixture and partially polarized quantum states; in this way, we propose a simple definition of the quantum polarization degree based on the recent concept of distance measure to an unpolarized distribution, which gives rise to a depolarization degree equivalent to an overlapping between the probability distribution of the quantum state and a non-polarized two-mode Gaussian distribution. The work is particularly intended to university physics teachers and graduate students as well as to physicists and specialists concerned with the issue of optical polarization.