Jan Florjanczyk

One of the most basic and intuitive properties of most information measures is that the amount of information carried by a physical system must be bounded by its size. We consider locking, which occurs when classical information encoded into a quantum system can be extracted given access to the cyphertext only with much less probability than expected. We show that locking occurs with high probability in physical systems whose internal dynamics are sufficiently random, with implications for thermodynamics and the black hole information problem. We also generalise locking to the case where the measuring device is allowed to share entanglement with the cyphertext-key compound system.