10,863 research outputs found
Quantum Walk on a Line with Two Entangled Particles
We introduce the concept of a quantum walk with two particles and study it
for the case of a discrete time walk on a line. A quantum walk with more than
one particle may contain entanglement, thus offering a resource unavailable in
the classical scenario and which can present interesting advantages. In this
work, we show how the entanglement and the relative phase between the states
describing the coin degree of freedom of each particle will influence the
evolution of the quantum walk. In particular, the probability to find at least
one particle in a certain position after steps of the walk, as well as the
average distance between the two particles, can be larger or smaller than the
case of two unentangled particles, depending on the initial conditions we
choose. This resource can then be tuned according to our needs, in particular
to enhance a given application (algorithmic or other) based on a quantum walk.
Experimental implementations are briefly discussed
Spin-Space Entanglement Transfer and Quantum Statistics
Both the topics of entanglement and particle statistics have aroused enormous
research interest since the advent of quantum mechanics. Using two pairs of
entangled particles we show that indistinguishability enforces a transfer of
entanglement from the internal to the spatial degrees of freedom without any
interaction between these degrees of freedom. Moreover, sub-ensembles selected
by local measurements of the path will in general have different amounts of
entanglement in the internal degrees of freedom depending on the statistics
(either fermionic or bosonic) of the particles involved.Comment: 5 figures. Various changes for clarification and references adde
Performances of silicone coated high resistive bakelite RPC
Performances of several single gap (gas gap 2 mm) prototype Resistive Plate
Chambers (RPC) made of high resistive ({\rho} \sim 1010 - 1012 {\Omega} cm)
bakelite, commercially available in India have been studied in recent times. To
make the inner electrode surfaces smooth, a thin coating of silicone has been
applied. An efficiency > 90% and time resolution \sim 2 ns (FWHM) have been
obtained for both the streamer and the avalanche mode. The induced charge
distributions of those silicone coated RPC are studied and the results are
presented. A numerical study on the effect of surface roughness of the
resistive electrodes on the electric field of the device has been carried out
using Garfield-neBEM code. A few results for a simplified model representing
surface roughness, measured using a surface profilometer for the bakelite
surfaces, have also been presented
Optimal State Discrimination Using Particle Statistics
We present an application of particle statistics to the problem of optimal
ambiguous discrimination of quantum states. The states to be discriminated are
encoded in the internal degrees of freedom of identical particles, and we use
the bunching and antibunching of the external degrees of freedom to
discriminate between various internal states. We show that we can achieve the
optimal single-shot discrimination probability using only the effects of
particle statistics. We discuss interesting applications of our method to
detecting entanglement and purifying mixed states. Our scheme can easily be
implemented with the current technology
Weighted Scale-free Networks in Euclidean Space Using Local Selection Rule
A spatial scale-free network is introduced and studied whose motivation has
been originated in the growing Internet as well as the Airport networks. We
argue that in these real-world networks a new node necessarily selects one of
its neighbouring local nodes for connection and is not controlled by the
preferential attachment as in the Barab\'asi-Albert (BA) model. This
observation has been mimicked in our model where the nodes pop-up at randomly
located positions in the Euclidean space and are connected to one end of the
nearest link. In spite of this crucial difference it is observed that the
leading behaviour of our network is like the BA model. Defining link weight as
an algebraic power of its Euclidean length, the weight distribution and the
non-linear dependence of the nodal strength on the degree are analytically
calculated. It is claimed that a power law decay of the link weights with time
ensures such a non-linear behavior. Switching off the Euclidean space from the
same model yields a much simpler definition of the Barab\'asi-Albert model
where numerical effort grows linearly with .Comment: 6 pages, 6 figure
Entanglement Concentration Using Quantum Statistics
We propose an entanglement concentration scheme which uses only the effects
of quantum statistics of indistinguishable particles. This establishes the fact
that useful quantum information processing can be accomplished by quantum
statistics alone. Due to the basis independence of statistical effects, our
protocol requires less knowledge of the initial state than most entanglement
concentration schemes. Moreover, no explicit controlled operation is required
at any stage.Comment: 2 figure
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