Quantum communication experiments with entangled photon pairs

Today, perhaps more than ever before, the security of information and communication is increasingly important. The cryptographic protocols used in classical cryptography are based on mathematical algorithms and can be breached. On the other hand, the laws of quantum physics enable quantum key distribution (QKD) and it is possible to achieve absolute security of communication based on the fundamental laws of nature. Anyone who would eavesdrop QKD-based communication must perform a measurement, which implies an impact on the system that can be detected by the sender and receiver. In this paper, we present a brief overview of QKD implementations and our experimental setup for generation of quantum key. Using this setup, we measured violation of the Bell's inequality of 114 standard deviations from the classical boundary, which confirms the non-local behavior of the entangled photon pairs. One can also use this source to create hybrid connections in combination with both optical fibers and free space.