1. You wish to set up a secure communication channel with your friend, in which confidential messages are locked using some symmetric cryptographic algorithm that requires a binary key of length 10 bits. You both have access to a quantum channel, which you will use to securely set up that key. Approximately what should be the length of the random bit string you initially create? Create a random bit string of the length you choose, using a random number generator, such as that provided by Matlab or Excel. 2. Likewise generate your own random filter sequence comprising rectilinear (+) and diagonal (x) filters. 3. Prepare the photo polarisations based on your randomly chosen bit string and filters. 4. From the perspective of your friend, randomly generate your filter sequence. 5. You friend receives the photons you transmitted. What is the sequence of photon polarisations he/she receives? 6. You and your friend publicly discuss your filters. What is the resulting key you agree on? Is it long enough? Or too long? 7. Research the old one-time-pad cipher. How can QKD be used to make this cipher both secure and robust to multiple uses