Regular quantum graphs

We introduce the concept of regular quantum graphs and construct connected quantum graphs with discrete symmetries. The method is based on a decomposition of the quantum propagator in terms of permutation matrices which control the way incoming and outgoing channels at vertex scattering processes are connected. Symmetry properties of the quantum graph as well as its spectral statistics depend on the particular choice of permutation matrices, also called connectivity matrices, and can now be easily controlled. The method may find applications in the study of quantum random walks networks and may also prove to be useful in analysing universality in spectral statistics.Comment: 12 pages, 3 figure

Quantum search algorithms on a regular lattice

Quantum algorithms for searching one or more marked items on a d-dimensional lattice provide an extension of Grover's search algorithm including a spatial component. We demonstrate that these lattice search algorithms can be viewed in terms of the level dynamics near an avoided crossing of a one-parameter family of quantum random walks. We give approximations for both the level-splitting at the avoided crossing and the effectively two-dimensional subspace of the full Hilbert space spanning the level crossing. This makes it possible to give the leading order behaviour for the search time and the localisation probability in the limit of large lattice size including the leading order coefficients. For d=2 and d=3, these coefficients are calculated explicitly. Closed form expressions are given for higher dimensions

The cost of passenger delay to airlines in Europe - consultation document

This document updates estimates, previously adopted by EUROCONTROL, of the cost of passenger delay to European airlines. It draws on various sources of evidence, with a particular focus on the impact of Regulation (EC) No 261/2004, which establishes the rules for compensation and assistance to airline passengers in the event of denied boarding, cancellation or delay. It reviews major legal rulings on the Regulation to assess the broader cost impacts on airlines. It also assesses changes to the Regulation being considered by the European Commission, in order to ensure that the cost framework used for these delay cost calculations is sufficiently adaptable to such changes and to gain an insight into the likely future regulatory emphasis, particularly where this has a financial implication for airlines. The objective is to produce cost reference values for industry use, which accurately reflect airline delay costs. These results will be used to develop European reference values for use by industry and in wider research, updating previously published values adopted by EUROCONTROL. The Performance Review commission of EUROCONTROL has used such findings in the past, and is likely to do so again in the future. Feedback on the delay cost values presented in this document is invited, particularly from airlines. All feedback will be treated in confidence and suggestions for evidence-based adjustments will be taken into account

The challenge of managing airline delay costs

Estimates of airline delay costs as a function of delay magnitude are combined with fuel and (future) emissions charges to make cost-benefit trade-offs in the pre-departure and airborne phases. Hypothetical scenarios for the distribution of flow management slots are explored in terms of their cost and target-setting implications. The general superiority of passenger-centric metrics is of significance for delay measurement, although flight delays are still the only commonly-reported type of metric in both the US and Europe. There is a particular need for further research into reactionary (network) effects, especially with regard to passenger metrics and flow management delay

European airline delay cost reference values

The objective of this report is to provide users with updated reference values for the cost of delay to European airlines. It updates previous reporting (appended herewith) based on 2010 as the reference year. This new report presents costs for the reference year 2014 and extends the range of aircraft covered from 12 to 15, generated by a fully updated version of the model