37,883 research outputs found
Simple scheme for two-qubit Grover search in cavity QED
Following the proposal by F. Yamaguchi et al.[Phys. Rev. A 66, 010302 (R)
(2002)], we present an alternative way to implement the two-qubit Grover search
algorithm in cavity QED. Compared with F. Yamaguchi et al.'s proposal, with a
strong resonant classical field added, our method is insensitive to both the
cavity decay and thermal field, and doesn't require that the cavity remain in
the vacuum state throughout the procedure. Moreover, the qubit definitions are
the same for both atoms, which makes the experiment easier. The strictly
numerical simulation shows that our proposal is good enough to demonstrate a
two-qubit Grover's search with high fidelity.Comment: manuscript 10 pages, 2 figures, to appear in Phys. Rev.
A longitudinal study of migration propensities for mixed-ethnic unions in England and Wales
This research was funded by the ESRC under the Understanding Population Trends and Processes (UPTAP) programme (Award Ref: RES-163-25-0045).Most studies investigating residential segregation of ethnic minorities ignore the fact that the majority of adults live in couples. In recent years there has been a growth in the number of mixed-ethnic unions that involve a minority member and a white member. To our knowledge, hardly any research has been undertaken to explicitly examine whether the ethnic mix within households has an impact on the residential mobility of households in terms of the ethnic mix of destination neighbourhoods. Our study addresses this research gap and examines the tendencies of mobility among mixed-ethnic unions in comparison with their co-ethnic peers. We used data from the Longitudinal Study for England and Wales. Our statistical analysis supports the spatial assimilation theory; ethnic minorities move towards less deprived areas and to a lesser extent also towards less ethnically concentrated areas. However, the types of destination neighbourhood of minority people living in mixed-ethnic unions varied greatly with the ethnicity of the ethnic minority partner.PostprintPeer reviewe
Generation of entangled photons by trapped ions in microcavities under a magnetic field gradient
We propose a potential scheme to generate entangled photons by manipulating
trapped ions embedded in two-mode microcavities, respectively, assisted by a
magnetic field gradient. By means of the spin-spin coupling due to the magnetic
field gradient and the Coulomb repulsion between the ions, we show how to
efficiently generate entangled photons by detecting the internal states of the
trapped ions. We emphasize that our scheme is advantageous to create complete
sets of entangled multi-photon states. The requirement and the experimental
feasibility of our proposal are discussed in detail.Comment: 2 Tables, 2 Figures, To appear in Phys. Rev.
Entanglement of separate nitrogen-vacancy centers coupled to a whispering-gallery mode cavity
We present a quantum electrodynamical model involving nitrogen-vacancy
centers coupled to a whispering-gallery mode cavity. Two schemes are considered
to create W state and Bell state, respectively. One of the schemes makes use of
the Raman transition with the cavity field virtually excited; The other enables
the Bell state preparation and quantum information transfer by virtue of dark
state evolution and adiabatic passage, which is tolerant to ambient noise and
experimental parameter fluctuations. We justify our schemes by considering the
experimental feasibility and challenge using currently available technology.Comment: 8 pages and 5 figure
Alternative scheme for two-qubit conditional phase gate by adiabatic passage under dissipation
We check a recent proposal [H. Goto and K. Ichimura Phys. Rev. A 70, 012305
(2004)] for controlled phase gate through adiabatic passage under the influence
of spontaneous emission and the cavity decay. We show a modification of above
proposal could be used to generate the necessary conditional phase gates in the
two-qubit Grover search. Conditioned on no photon leakage either from the
atomic excited state or from the cavity mode during the gating period, we
numerically analyze the success probability and the fidelity of the two-qubit
conditional phase gate by adiabatic passage. The comparison made between our
proposed gating scheme and a previous one shows that Goto and Ichimura's scheme
is an alternative and feasible way in the optical cavity regime for two-qubit
gates and could be generalised in principle to multi-qubit gates.Comment: to appear in J. Phys.
Some integral inequalities on time scales
In this paper, some new integral inequalities on time scales are presented by
using elementarily analytic methods in calculus of time scales.Comment: 8 page
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