Polarization states of the two-photon system

欣 王

Vladimir Lvovich Lyuboshitz, Vladimir Lvovich Lyuboshitz

The correlations of the linear and circular polarizations in the system of two photons have been theoretically investigated. The polarization of a two‐photon state is described by the one‐photon Stokes parameters and by the components of the correlation “tensor” in the Stokes space. The correlations between the Stokes parameters in the case of the two‐photon decays are considered.

Frederik Jozef Belinfante

Eugen Muchowski

A system of two polarized photons in singlet state appears as being in one of two product states independent of any measurement. These states depend on the selected polarization angles. With the polarizers on either side perpendicular to each other, both photons pass the polarizers without any disturbance. Action at a distance is therefore not needed to explain the results of the measurements. In general, the elements of physical reality demanded by EPR are the polarization states of the two photons of the entangled pair. As these are local elements in the regions of space of the polarizers the EPR paradox for the case of entangled photons can be regarded as resolved.

Daniel J. Gauthier, Olivier Pfister, William J. Brown +1 more

Jeffrey Bub

Chapter 2 clarifies the connection between Bananaworld correlations and quantum correlations with an introduction to the simplest quantum systems, qubits, using polarized photons – particles of light – as the standard example. A “bit” is the basic unit of classical (Shannon) information, but the term is also used to refer to an elementary classical system that can be in one of two states. The corresponding elementary quantum system is referred to as a “qubit,” short for “quantum bit.” A photon is a qubit with respect to its state of polarization. The Born rule specifies the probability that a photon in a certain initial polarization state, prepared by passing the photon through a polarizing filter, will be detected by a photon detector after being directed to pass through a second polarizer called an “analyzer.” A pair of qubits can be in an “entangled” state. Two separated “maximally entangled” photons exhibit nonclassical correlations for appropriate polarization measurements analogous to Bananaworld correlations.