607,917 research outputs found
P systems with communication based on concentration
We consider a variant of P systems where the communication of objects is controlled by the "concentration" of these objects: after each evolution step, the objects are redistributed among the regions of the system in such a way that each region contains the same number of copies of each object (plus/minus one, when the number of objects is not divisible by the number of regions). We show that P systems of this form, with only one flip-flop catalyst but without using other control ingredients, can generate the Parikh images of all matrix languages. When an unbounded number of catalysts is available, a characterization of recursively enumerable sets of vectors of natural numbers is obtained (by systems with only one membrane)
Single-photon-assisted entanglement concentration of a multi-photon system in a partially entangled W state with weak cross-Kerr nonlinearity
We propose a nonlocal entanglement concentration protocol (ECP) for
-photon systems in a partially entangled W state, resorting to some
ancillary single photons and the parity-check measurement based on cross-Kerr
nonlinearity. One party in quantum communication first performs a parity-check
measurement on her photon in an -photon system and an ancillary photon, and
then she picks up the even-parity instance for obtaining the standard W state.
When she obtains an odd-parity instance, the system is in a less-entanglement
state and it is the resource in the next round of entanglement concentration.
By iterating the entanglement concentration process several times, the present
ECP has the total success probability approaching to the limit in theory. The
present ECP has the advantage of a high success probability. Moreover, the
present ECP requires only the -photon system itself and some ancillary
single photons, not two copies of the systems, which decreases the difficulty
of its implementation largely in experiment. It maybe have good applications in
quantum communication in future.Comment: 7 pages, 3 figure
Optimal nonlocal multipartite entanglement concentration based on projection measurements
We propose an optimal nonlocal entanglement concentration protocol (ECP) for
multi-photon systems in a partially entangled pure state, resorting to the
projection measurement on an additional photon. One party in quantum
communication first performs a parity-check measurement on her photon in an
N-photon system and an additional photon, and then she projects the additional
photon into an orthogonal Hilbert space for dividing the original -photon
systems into two groups. In the first group, the N parties will obtain a subset
of -photon systems in a maximally entangled state. In the second group, they
will obtain some less-entangled N-photon systems which are the resource for the
entanglement concentration in the next round. By iterating the entanglement
concentration process several times, the present ECP has the maximal success
probability which is just equivalent to the entanglement of the partially
entangled state. That is, this ECP is an optimal one.Comment: 5 pages, 4 figure
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