3,731 research outputs found
Efficient decomposition of quantum gates
Optimal implementation of quantum gates is crucial for designing a quantum
computer. We consider the matrix representation of an arbitrary multiqubit
gate. By ordering the basis vectors using the Gray code, we construct the
quantum circuit which is optimal in the sense of fully controlled single-qubit
gates and yet is equivalent with the multiqubit gate. In the second step of the
optimization, superfluous control bits are eliminated, which eventually results
in a smaller total number of the elementary gates. In our scheme the number of
controlled NOT gates is which coincides with the theoretical lower
bound.Comment: 4 pages, 2 figure
Polarization of lepton from scalar tau decay as a probe of neutralino mixing
The lepton arising from the scalar tau (\st) decay is naturally
polarized. \ptau depends on the left--right mixing of the \st and the
gaugino--higgsino mixing of the neutralino. The polarization \ptau could be
measured from the energy distribution of the decay products of at future
\epem colliders. A measurement of \ptauand of the \st production cross
section allows to determine both these mixing angles.Comment: 20 pages Latex, 5 figures(not included). compressed ps file of the
figures available at ftp://ftp.kek.jp/kek/preprints/TH/TH-425/fig.ps.g
Under the radar? Modern slavery and labour exploitation risks for the hotel industry
The UK's tourism and hospitality industries, having the highest concentration of migrant workers compared to other industries, face complex challenges in managing the risks of labour exploitation and modern slavery (MS); issues largely neglected in academic research. New employment models risk weakening workers' power in employment relations, potentially leading to increased vulnerability and exploitation risk. Based on analysing primary and secondary sources, this article examines the nature of these risks. Our findings show the following drivers: power imbalances; possible enforcement gaps; normalisation and moralisation of possible exploitation; and potential threats posed by macro-level political and socioeconomic issues/events; these, including more competitive labour markets, paradoxically also present opportunities. We develop significant, novel theoretical contributions and propose the new ‘(in)conspicuous exploitariat’ concept, encapsulating their (dis)empowerment, and potential future risks/opportunities. The research advances theory, with implications for policy and practice, for both the UK and the international tourism and hospitality industries
Grown-in defects limiting the bulk lifetime of p-type float-zone silicon wafers
We investigate a recombination active grown-in defect limiting the bulk lifetime (τ bulk ) of high quality float-zone (FZ) p-type silicon wafers. After annealing the samples at temperatures between 80 °C and 400 °C, τ bulk was found to increase from ∼500 μs to ∼1.5 ms. By isochronal annealing the p-type samples between 80 °C and 400 °C for 30 min, the annihilation energy (Eann ) of the defect was determined to be 0.3 < Eann  < 0.7 eV. When the annihilated samples were phosphorus gettered at 880 °C or subject to 0.2 sun illumination for 24 h, τ bulk was found to degrade. However, when the samples were subsequently annealed at temperatures between 250 and 400 °C, the defect could be re-annihilated. The experimental results suggest that the defect limiting the lifetime in the p-type FZ silicon is not related to fast diffusing metallic impurities but rather to a lattice-impurity or an impurity-impurity metastable defect.This work has been supported by the Australian
Renewable Energy Agency (ARENA) fellowships program and
the Australian Research Council (ARC) Future Fellowships
program
Distribution of Alkalis (Na, Cs, Rb) Between Silicate and Sulfide: Implications for Planetary Volatile Depletion
The abundances of volatile elements in the Earth's mantle are correlated with their temperatures of condensation. This depletion can be due to either incomplete condensation of the elements during the nebula condensation or evaporation processes during planetary growth. Elements that have affinities with metals (siderophile) and sulfides (chalcophile) are additionally depleted due to their segregation into the core. Therefore, study of lithophile elements could be useful to isolate processes of volatilization and their effect on the abundance of the elements in the Earth's mantle. However, the correlation of these lithophile elements including alkali elements, with their temperatures of condensation shows a significant scatter, which is difficult to reconcile with a depletion by vaporization or incomplete condensation alone
11 x 11 Domineering is Solved: The first player wins
We have developed a program called MUDoS (Maastricht University Domineering
Solver) that solves Domineering positions in a very efficient way. This enables
the solution of known positions so far (up to the 10 x 10 board) much quicker
(measured in number of investigated nodes).
More importantly, it enables the solution of the 11 x 11 Domineering board, a
board up till now far out of reach of previous Domineering solvers. The
solution needed the investigation of 259,689,994,008 nodes, using almost half a
year of computation time on a single simple desktop computer. The results show
that under optimal play the first player wins the 11 x 11 Domineering game,
irrespective if Vertical or Horizontal starts the game.
In addition, several other boards hitherto unsolved were solved. Using the
convention that Vertical starts, the 8 x 15, 11 x 9, 12 x 8, 12 x 15, 14 x 8,
and 17 x 6 boards are all won by Vertical, whereas the 6 x 17, 8 x 12, 9 x 11,
and 11 x 10 boards are all won by Horizontal
P and T Odd Asymmetries in Lepton Flavor Violating Tau Decays
We calculated the differential cross sections of the processes in which one
of the pair created tau particles at an e^+ e^- collider decays into lepton
flavor violating final states e.g. tau -> mu gamma, tau -> 3 mu, tau -> mu ee.
Using the correlations between angular distributions of both sides of tau
decays, we can obtain information on parity and CP violations of lepton flavor
non-conserving interactions. The formulae derived here are useful in
distinguishing different models, since each model of physics beyond the
standard model predicts different angular correlations. We also calculate
angular distributions of the major background process to tau -> l gamma search,
namely tau -> l nu \bar{\nu} gamma, and discuss usefulness of the angular
correlation for background suppression.Comment: 31 pages, 5 figure
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