Abstract

State superpositions and entanglement are central notions in quantum physics which can be used to process information in non-classical ways. Two-level particles such as photons, ions, atoms or nuclear spins can encode binary information and play the role of quantum bits (qubits) in various quantum manipulations. Operation of simple quantum gates, teleportation of quantum states and secure cryptographic key distribution have been realized in this way. Great hopes have been raised that qubit manipulations could be extended to the operation of large systems, making it possible to build real quantum computers which would make full use of entanglement and realize some tasks (such as the factorization of large numbers) much more efficiently than classical machines.

© 2000 IEEE