Activity: Talk or presentation › Oral presentation
In order to transmit a secret message between a sender (Alice) and a receiver (Bob), both parties need a shared secret for encryption and decryption. Quantum Key Distribution (QKD) provides a secure way of generating such shared keys. The original BB84 protocol uses a two-dimensional polarization basis, limiting the information content of a single photon to 1 bit. Using the position of single photons as one basis and the Fourier space as second basis, one can construct a pair of mutually unbiased higher-dimensional bases. This improves not only the security of the protocol, but also the key generation rate. We present our experimental results with an encoding scheme using a Spatial Light Modulator (SLM) allowing two nearly orthogonal alphabets with in the order of 103 symbols and an information content per single photon of about 10 bit.