|a type of computer which uses the ability of quantum systems to be in many different states at once, thus allowing it to perform many different computations simultaneously|
A computer that exploits the quantum mechanical properties of superposition in order to allow a single operation to act on a large number of pieces of data. In a quantum computer, the data to be manipulated, represented in quantum bits, exists in all possible states simultaneously, in superposition. This allows a single operation to operate over all of these states at once, in contrast with a classical computer, which must carry out an operation for each state separately. Because of the difficulty of creating environments small enough for quantum effects to emerge but sufficiently isolated to prevent interaction with outside influences such as heat, only extremely rudimentary quantum computers currently exist, though algorithms for possible future devices are being developed.