26,974 research outputs found
The data aggregation problem in quantum hypothesis testing
We discuss the implications of quantum-classical Yule-Simpson effect for
quantum hypothesis testing in the presence of noise, and provide an
experimental demonstration of its occurrence in the problem of discriminating
which polarization quantum measurement has been actually performed by a
detector box designed to measure linear polarization of single-photon states
along a fixed but unknown direction.Comment: 4 pages, 2 figs, published versio
On the Graceful Game
A graceful labeling of a graph with edges consists of labeling the
vertices of with distinct integers from to such that, when each
edge is assigned as induced label the absolute difference of the labels of its
endpoints, all induced edge labels are distinct. Rosa established two well
known conjectures: all trees are graceful (1966) and all triangular cacti are
graceful (1988). In order to contribute to both conjectures we study graceful
labelings in the context of graph games. The Graceful game was introduced by
Tuza in 2017 as a two-players game on a connected graph in which the players
Alice and Bob take turns labeling the vertices with distinct integers from 0 to
. Alice's goal is to gracefully label the graph as Bob's goal is to prevent
it from happening. In this work, we study winning strategies for Alice and Bob
in complete graphs, paths, cycles, complete bipartite graphs, caterpillars,
prisms, wheels, helms, webs, gear graphs, hypercubes and some powers of paths
Dynamics of vitrimers: defects as a highway to stress relaxation
We propose a coarse-grained model to investigate stress relaxation in
star-polymer networks induced by dynamic bond exchange processes. We show how
the swapping mechanism, once activated, allows the network to reconfigure,
exploring distinct topological configurations, all of them characterised by
complete extent of reaction. Our results reveal the important role played by
topological defects in mediating the exchange reaction and speeding up stress
relaxation. The model provides a representation of the dynamics in vitrimers, a
new class of polymers characterized by bond swap mechanisms which preserve the
total number of bonds, as well as in other bond-exchange materials.Comment: 5 pages, 5 figures, with 6 pages SI appende
Compositional bisimulation metric reasoning with Probabilistic Process Calculi
We study which standard operators of probabilistic process calculi allow for
compositional reasoning with respect to bisimulation metric semantics. We argue
that uniform continuity (generalizing the earlier proposed property of
non-expansiveness) captures the essential nature of compositional reasoning and
allows now also to reason compositionally about recursive processes. We
characterize the distance between probabilistic processes composed by standard
process algebra operators. Combining these results, we demonstrate how
compositional reasoning about systems specified by continuous process algebra
operators allows for metric assume-guarantee like performance validation
Homodyning the of Gaussian states
We suggest a method to reconstruct the zero-delay-time second-order
correlation function of Gaussian states using a single homodyne
detector. To this purpose, we have found an analytic expression of
for single- and two-mode Gaussian states in terms of the elements of their
covariance matrix and the displacement amplitude. In the single-mode case we
demonstrate our scheme experimentally, and also show that when the input state
is nonclassical, there exist a threshold value of the coherent amplitude, and a
range of values of the complex squeezing parameter, above which . For amplitude squeezing and real coherent amplitude, the threshold turns
out to be a necessary and sufficient condition for the nonclassicality of the
state. Analogous results hold also for two-mode squeezed thermal states.Comment: 7 pages, 6 figure
Dynamically localized systems: entanglement exponential sensitivity and efficient quantum simulations
We study the pairwise entanglement present in a quantum computer that
simulates a dynamically localized system. We show that the concurrence is
exponentially sensitive to changes in the Hamiltonian of the simulated system.
Moreover, concurrence is exponentially sensitive to the ``logic'' position of
the qubits chosen. These sensitivities could be experimentally checked
efficiently by means of quantum simulations with less than ten qubits. We also
show that the feasibility of efficient quantum simulations is deeply connected
to the dynamical regime of the simulated system.Comment: 5 pages, 6 figure
Demonstration of a programmable source of two-photon multiqubit entangled states
We suggest and demonstrate a novel source of two-photon multipartite
entangled states which exploits the transverse spatial structure of spontaneous
parametric downconversion together with a programmable spatial light modulator
(SLM). The 1D SLM is used to perform polarization entanglement purification and
to realize arbitrary phase-gates between polarization and momentum degrees of
freedom of photons. We experimentally demonstrate our scheme by generating
two-photon three qubit linear cluster states with high fidelity using a diode
laser pump with a limited coherence time and power on the crystal as low as
2.5$mW.Comment: 5 pages, 4 figures, to appear on PR
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