The development and theory of an experiment to investigate quantum computation with trapped calcium ions is described. The ion trap, laser and ion requirements are determined, and the parameters required for quantum logic operations as well as simple quantum factoring are described.
Modern optical networking techniques have the potential to greatly extend the applicability of quantum communications by moving beyond simple point-to-point optical links, and by leveraging existing fibre infrastructures. We experimentally demonstrate many of the fundamental capabilities that are required. These include optical-layer multiplexing,… (More)
Quantum key distribution (QKD) has the potential for widespread real-world applications. To date no secure long-distance experiment has demonstrated the truly practical operation needed to move QKD from the laboratory to the real world due largely to limitations in synchronization and poor detector performance. Here we report results obtained using a fully… (More)
The significance of quantum computation for cryptography is discussed. Following a brief survey of the requirements for quantum computational hardware, an overview of the ion-trap quantum-computation project at Los Alamos is presented. The physical limitations to quantum computation with trapped ions are analysed and an assessment of the computational… (More)
Quantum cryptography is an emerging technology in which two parties may simultaneously generate shared, secret cryptographic key material using the transmission of quantum states of light whose security is based on the inviolability of the laws of quantum mechanics. An adversary can neither successfully tap the key transmissions, nor evade detection, owing… (More)
We have implemented the 'six-state' quantum cryptography protocol using polarization-entangled photon pairs, in which the polarization of each photon of a pair is measured in one of three randomly chosen bases. For a given amount of eavesdropping, this protocol results in a larger error rate than in four-or two-state protocols, but reduces the number of… (More)
The secure distribution of the secret random bit sequences known as " key " material, is an essential precursor to their use for the encryption and decryption of confidential communications. Quantum cryptography is an emerging technology for secure key distribution with single-photon transmissions: Heisenberg's uncertainty principle ensures that an… (More)