Optical Quantum Computation

We review the field of Optical Quantum Computation, considering the various implementations that have been proposed and the experimental progress that has been made toward realizing them. We examine both linear and nonlinear approaches and both particle and field encodings. In particular we discuss the prospects for large scale optical quantum computing in terms of the most promising physical architectures and the technical requirements for realizing them

Phase-dependent decoherence of optical transitions in Pr3+:LaF3 in the presence of a driving field

The decoherence times of orthogonally phased components of the optical transition dipole moment in a two-level system have been observed to differ by an order of magnitude. This phase anisotropy is observed in coherent transient experiments where an optical driving field is present during extended periods of decoherence. The decoherence time of the component of the dipole moment in phase with the driving field is extended compared to T_2, obtained from two-pulse photon echoes, in analogy with the spin locking technique of NMR.Comment: 5 pages, 2 figures; replaced with published versio

A Social Networking Strategy for Improving Knowledge Management and Communication in the Travel Industry

In today’s technology-driven marketplace, the adoption and management of corporate and customer-facing Social Networking Sites (SNs) is often viewed as a key success factor for Travel Industry (TI) organisations. Knowledge management and the sharing of expertise and experiences through communication between internal and external stakeholders via social networks is an activity which TI organisations are aiming to exploit in order to improve the open sharing, retrieval, organisation and leveraging of knowledge. Through a study of currently-available literature relating to social networking adoption within the TI and a case study analysis of corporate social networking practices at three multi-national TI organisations (British Airways, Thomas Cook and Marriott Hotels), it may be observed that correlations exist between the development of social networking and the processes TI organisations now use to manage knowledge. We explore how these companies are currently utilizing SNs to improve knowledge management practices inside and outside of their organisational boundaries. From our analysis, lessons may emerge as to how TI companies are gaining competitive advantage through the use of social networking; a proposed strategy is identified to determine how TI organisations may make best use of social networks

Violation of the Leggett-Garg inequality with weak measurements of photons

By weakly measuring the polarization of a photon between two strong polarization measurements, we experimentally investigate the correlation between the appearance of anomalous values in quantum weak measurements, and the violation of realism and non-intrusiveness of measurements. A quantitative formulation of the latter concept is expressed in terms of a Leggett-Garg inequality for the outcomes of subsequent measurements of an individual quantum system. We experimentally violate the Leggett-Garg inequality for several measurement strengths. Furthermore, we experimentally demonstrate that there is a one-to-one correlation between achieving strange weak values and violating the Leggett-Garg inequality.Comment: 5 pages, 4 figure

Experimental semi-device-independent certification of entangled measurements

Certifying the entanglement of quantum states with Bell inequalities allows one to guarantee the security of quantum information protocols independently of imperfections in the measuring devices. Here we present a similar procedure for witnessing entangled measurements, which play a central role in many quantum information tasks. Our procedure is termed semi-device-independent, as it uses uncharacterized quantum preparations of fixed Hilbert space dimension. Using a photonic setup, we experimentally certify an entangled measurement using measurement statistics only. We also apply our techniques to certify unentangled but nevertheless inherently quantum measurements.Comment: 7 pages, 2 figure