Thermal state quantum key distribution

We analyse a central broadcast continuous variable quantum key distribution protocol in which beam produced by thermal source is used to create secret between two parties, Alice and Bob. A splitter divides the initial into pair of output beams, are sent Bob, with Eve intercepting Bob's beam. investigate detail, calculating mutual informations through analytic methods comparing results outputs Monte Carlo simulation protocol. In lossless system, we find that lower bound on rate remains positive under attack, provided Bob receives nonzero proportion initially him. This suggests state could be experimentally produce secure keys.