22,755 research outputs found
Multi-step quantum secure direct communication using multi-particle Green-Horne-Zeilinger state
A multi-step quantum secure direct communication protocol using blocks of
multi-particle maximally entangled state is proposed. In this protocol, the
particles in a Green-Horne-Zeilinger state are sent from Alice to Bob in
batches in several steps. It has the advantage of high efficiency and high
source capacity.Comment: 4 pages and 1 figure. Revised version of Optics Communications 253
(2005(1
On the Strichartz estimates for the kinetic transport equation
We show that the endpoint Strichartz estimate for the kinetic transport
equation is false in all dimensions. We also present a new approach to proving
the non-endpoint cases using multilinear analysis.Comment: 5 page
Estimates for the kinetic transport equation in hyperbolic Sobolev spaces
We establish smoothing estimates in the framework of hyperbolic Sobolev
spaces for the velocity averaging operator of the solution of the
kinetic transport equation. If the velocity domain is either the unit sphere or
the unit ball, then, for any exponents and , we find a characterisation
of the exponents and , except possibly for an endpoint case,
for which is bounded from space-velocity
to space-time . Here, and are the classical
and hyperbolic derivative operators, respectively. In fact, we shall provide an
argument which unifies these velocity domains and the velocity averaging
estimates in either case are shown to be equivalent to mixed-norm bounds on the
cone multiplier operator acting on . We develop our ideas further in
several ways, including estimates for initial data lying in certain Besov
spaces, for which a key tool in the proof is the sharp decoupling
theorem recently established by Bourgain and Demeter. We also show that the
level of permissible smoothness increases significantly if we restrict
attention to initial data which are radially symmetric in the spatial variable.Comment: 23 pages; some additional arguments added to the proof of Theorem 1.3
in the case d=3; to appear in Journal de Math\'ematiques Pures et
Appliqu\'ee
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An investigation into the impact of deprivation on demographic inequalities in adults
This research investigates the impact of deprivation on demographic inequalities in England and Wales among adults. Using demographic measures including the modal age at death, life expectancy, lifespan variation and mortality, it shows a negative correlation with deprivation as measured by the 2015 Index of Multiple Deprivation. Although it finds that life expectancy is increasing overall and the gap between men and women is lessening, improvements are slower paced in more deprived areas such that the gap between rich and poor is slowly worsening over time. Men are more adversely impacted by deprivation than women with the gap in period life expectancy at age 30 in 2015 between the top and bottom 1% of deprived neighbourhoods at 10.9 years for men and 8.4 years for women. Between 2001 and 2015 inequalities in male mortality rates at age 44 were 4.4 times greater in the most deprived 10% of neighbourhoods than those in the 10% least deprived, and were much higher than in intervening deciles. The worst deprivation is concentrated in specific areas. For example, in 22 out of 326 English districts 25% or more of neighbourhoods are in the most deprived 10% and in 5 districts it is 40% or above
Stability of the Brascamp-Lieb constant and applications
We prove that the best constant in the general Brascamp-Lieb inequality is a
locally bounded function of the underlying linear transformations. As
applications we deduce certain very general Fourier restriction, Kakeya-type,
and nonlinear variants of the Brascamp-Lieb inequality which have arisen
recently in harmonic analysis
Experimental Implementation of Projective Measurement in Bell Basis
A scheme for direct projection of a quantum state on Bell states is
described. The method is based on constructing an average Hamiltonian with Bell
eigenstates and then, projecting the state on these eigenstates. The projection
is performed by adding the results of a direct and time-reversed evolution.
Experimental demonstration is shown for pairs of dipolar-coupled nuclear spins.Comment: 10 pages, 3 figures, submitte
Bound on distributed entanglement
Using the convex-roof extended negativity and the negativity of assistance as
quantifications of bipartite entanglement, we consider the possible
remotely-distributed entanglement. For two pure states and
on bipartite systems and , we first show that the
possible amount of entanglement remotely distributed on the system by
joint measurement on the system is not less than the product of two
amounts of entanglement for the states and
in two-qubit and two-qutrit systems. We also provide some sufficient
conditions, for which the result can be generalized into higher-dimensional
quantum systems.Comment: 5 page
Transfer information remotely via noise entangled coherent channels
In this contribution, a generalized protocol of quantum teleportation is
suggested to investigate the possibility of remotely transfer unknown
multiparities entangled coherent state. A theoretical technique is introduced
to generate maximum entangled coherent states which are used as quantum
channels. We show that the mean photon number plays a central role on the
fidelity of the transferred information. The noise parameter can be considered
as a control parameter only for small values of the mean photon number
An N-bit digitally variable ultra wideband pulse generator for GPR and UWB applications
This paper presents a low-cost Ultra Wideband (UWB) pulse generator that can vary the pulse duration digitally by using a Step Recovery Diode (SRD), microstrip transmission lines and PIN diodes. First, a sharp edge is generated by using a SRD circuitry. Then a pulse is formed from the sharp edge through the use of transmission lines and the PIN diodes. Based on the number of transmission lines (N), the duration of the pulse can be varied in steps. The UWB pulse generator circuits are implemented on an FR-4 substrate using microstrip line technology and UWB pulses with durations of 550 to 2400 psec are measured. N2 Ke
Quantum Direct Communication with Authentication
We propose two Quantum Direct Communication (QDC) protocols with user
authentication. Users can identify each other by checking the correlation of
Greenberger-Horne-Zeilinger (GHZ) states. Alice can directly send a secret
message to Bob using the remaining GHZ states after authentication. Our second
QDC protocol can be used even though there is no quantum link between Alice and
Bob. The security of the transmitted message is guaranteed by properties of
entanglement of GHZ states.Comment: 9 pages, 3 figures and 2 table
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