| （英） |
One of the methods of generating a polarized entangled photon pair is to use an emitted photon pair from a biexciton. The polarization-entanglement of the photon pair is considered to correspond to angular-momentum-entanglement of two excitons in the biexciton. However, the angular momentum is not a conserved quantity because crystals do not have continuous rotational symmetry. Instead, a pseudo-angular momentum, which is conserved in systems with discrete rotational symmetry, should be considered. In addition, since excitons have degrees of freedom other than the pseudo-angular momentum, quantum entanglement related only to the pseudo-angular momentum needs to be formulated appropriately. With these considerations in mind, we investigate the relation between the pseudo-angular-momentum-entanglement in a biexciton and the polarization-entanglement of a photon pair emitted from the biexciton, using a lattice model with four-fold symmetry. |