128 research outputs found
Reply to "Comment on: A Quantum Approach to Static Games of Complete Information"
This is a reply to the paper by S.C.Benjamin, quant-ph/0008127.Comment: 2 pages, Latex, submitted to Phys. Lett.
Reply to Marinatto's comment on "Bell's theorem without inequalities and without alignments"
Marinatto claims that in the proof of Bell's theorem without inequalities and
without alignments [A. Cabello, Phys. Rev. Lett. 91, 230403 (2003)], local
observables cannot be measured by means of tests on individual qubits.
Marinatto's claim is incorrect. To support this, the proof is explicitly
rewritten in terms of tests on individual qubits.Comment: REVTeX4, 1 pag
Quantum repeated games
In a two-stage repeated classical game of prisoners' dilemma the knowledge
that both players will defect in the second stage makes the players to defect
in the first stage as well. We find a quantum version of this repeated game
where the players decide to cooperate in the first stage while knowing that
both will defect in the second.Comment: Revised in the light of referee's comments. Latex, 10 pages, 1 eps
figure, submitted to Physics Letters
Comment on: "A quantum approach to static games of complete information''
Recently Marinatto and Weber introduced an interesting new scheme for
quantizing games, and applied their scheme to the famous game 'Battle of the
Sexes'. In this Comment we make two observations: (a) the overall quantization
scheme is fundamentally very similar to a previous scheme proposed by Eisert et
al., and (b) in contrast to a main claim of the paper, the quantum Battle of
the Sexes game does not have a unique solution - a similar dilemma exists in
both the classical and the quantum versions.Comment: 2 pages, 1 figur
On deciding whether a Boolean function is constant or not
We study the probability of making an error if, by querying an oracle a fixed
number of times, we declare constant a randomly chosen n-bit
Boolean function. We compare the classical and the quantum case, and we
determine for how many oracle-queries k and for how many bits n one querying
procedure is more efficient than the other.Comment: 8 pages, Latex, 5 figures; accepted for publication on International
Journal of Quantum Informatio
Which Kind of Two-Particle States Can Be Teleported through a Three-Particle Quantum Channel?
The use of a three-particle quantum channel to teleport entangled states
through a slight modification of the standard teleportation procedure is
studied. It is shown that it is not possible to perform successful
teleportation of an arbitrary and unknown two-particle entangled state,
following our version of the standard teleportation procedure. On the contrary,
it is shown which, and in how many different ways, particular classes of
two-particle states can be teleported.Comment: 11 pages, Latex, to appear in Found.Phys.Let
Nonlocality without inequalities
We prove that every conceivable hidden variable model reproducing the quantum
mechanical predictions of almost any entangled state must necessarily violate
Bell's locality condition. The proof does not involve the consideration of any
Bell inequality but it rests on simple set theoretic arguments and it works for
almost any noncompletely factorizable state vector associated to any number of
particles whose Hilbert spaces have arbitrary dimensionality.Comment: 10 pages; Latex; Talk delivered at ICSSUR'05, Besancon, France, 2-6
May 2005; to be published on J. Opt. B (special issue
Entanglement and Properties
Various topics concerning the entanglement of composite quantum systems are
considered with particular emphasis concerning the strict relations of such a
problem with the one of attributing objective properties to the constituents.
In particular we will focus our attention to composite quantum systems composed
of identical constituents, with the purpose of dealing with subtle issues,
which have never been adequately discussed in the literature, originating from
the true indistinguishability of the subsystems involved.Comment: 10 pages, Latex, corrected typo
Hardy's criterion of nonlocality for mixed states
We generalize Hardy's proof of nonlocality to the case of bipartite mixed
statistical operators, and we exhibit a necessary condition which has to be
satisfied by any given mixed state in order that a local and realistic
hidden variable model exists which accounts for the quantum mechanical
predictions implied by . Failure of this condition will imply both the
impossibility of any local explanation of certain joint probability
distributions in terms of hidden variables and the nonseparability of the
considered mixed statistical operator. Our result can be also used to determine
the maximum amount of noise, arising from imperfect experimental
implementations of the original Hardy's proof of nonlocality, in presence of
which it is still possible to put into evidence the nonlocal features of
certain mixed states.Comment: 7 pages, RevTe
- âŠ