In quantum information processing, the fundamental rules of information representation are different than in the classical setting. The fundamental unretrievability of some forms of information from quantum memory enable unique capabilities that enhance privacy and security. Unique correlations between quantum bits, referred to as quantum entanglement, enable fundamentally faster algorithms for important computational problems. Quantum bits are very delicate, and require extraordinarily low noise levels in order that they can be stored successfully. However, the long-term storage of quantum information is not hopeless, with relatively new discoveries of unique features of quantum entanglement showing that effective use of redundancy should make possible the solution of the quantum memory problem. Laboratory capabilities are just starting to make it possible to test these ideas, and a clear concept of the architectural solutions to scalable quantum computing is emerging.

We expand on our work on quantum data hiding - hiding classical data among parties who are restricted to performing only local quantum operations and classical communication (LOCC). We review our scheme that hides one bit between two parties using Bell (1964) states, and we derive upper and lower bounds on the secrecy of the hiding scheme. We provide an explicit bound showing that multiple bits can be hidden bitwise with our scheme. We give a preparation of the hiding states as an efficient quantum computation that uses at most one ebit of entanglement. A candidate data-hiding scheme that does not use entanglement is presented. We show how our scheme for quantum data hiding can be used in a conditionally secure quantum bit commitment scheme.