Entangled photon-pair source using a wedge-shaped nonlinear crystal

Entangled photon pairs constitute a crucial resource in quantum technologies. The current technique for preparing photon pairs involves performing spontaneous parametric down-conversion (SPDC) in bulk nonlinear crystals. The increased prominence of quantum technologies has led to a growing interest in high performance entangled photon-pair sources. However, the birefringence walk-off caused by nonlinear crystals affects the quality of the entangled photon pairs generated in SPDC. This letter presents an innovative approach for producing entangled photon pairs using a wedge-shaped nonlinear crystal to compensate for the birefringence walkoff. The proposed scheme features a basic entanglement source path, which can be applied to other methods of preparing entangled photon pairs. An experiment demonstrated that this method can produce high-quality entangled photon pairs with a high degree of entanglement, paving the way for the development of practical quantum communication, sensing, and computation.