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 $\rho$ 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 $q$ and $r$, we find a characterisation of the exponents $\beta_+$ and $\beta_-$, except possibly for an endpoint case, for which $D_+^{\beta_+}D_-^{\beta_-} \rho$ is bounded from space-velocity $L^2_{x,v}$ to space-time $L^q_tL^r_x$. Here, $D_+$ and $D_-$ 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 $L^2$. 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 $\ell^p$ 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

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 $\ket{\phi}_{AB}$ and $\ket{\psi}_{CD}$ on bipartite systems $AB$ and $CD$, we first show that the possible amount of entanglement remotely distributed on the system $AC$ by joint measurement on the system $BD$ is not less than the product of two amounts of entanglement for the states $\ket{\phi}_{AB}$ and $\ket{\psi}_{CD}$ 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