Memory Hierarchies for Quantum Data

Computing with quantum states may be the most efficient approach to solving some problems which take exponential time on conventional computers. Quantum states, however, are short-lived without constant error correction involving tremendous overheads. We propose to reduce these overheads by storing quantum data in a hierarchical structure. Large groups of quantum bits can be encoded together to reduce overhead in mass storage, but smaller groups are needed to support the working set of a computation.