266,365 research outputs found
Interferometric distillation and determination of unknown two-qubit entanglement
We propose a scheme for both distilling and quantifying entanglement,
applicable to individual copies of an arbitrary unknown two-qubit state. It is
realized in a usual two-qubit interferometry with local filtering. Proper
filtering operation for the maximal distillation of the state is achieved, by
erasing single-qubit interference, and then the concurrence of the state is
determined directly from the visibilities of two-qubit interference. We compare
the scheme with full state tomography
Origin of the mixed-order transition in multiplex networks: the Ashkin-Teller model
Recently, diverse phase transition (PT) types have been obtained in multiplex
networks, such as discontinuous, continuous, and mixed-order PTs. However, they
emerge from individual systems, and there is no theoretical understanding of
such PTs in a single framework. Here, we study a spin model called the
Ashkin-Teller (AT) model in a mono-layer scale-free network; this can be
regarded as a model of two species of Ising spin placed on each layer of a
double-layer network. The four-spin interaction in the AT model represents the
inter-layer interaction in the multiplex network. Diverse PTs emerge depending
on the inter-layer coupling strength and network structure. Especially, we find
that mixed-order PTs occur at the critical end points. The origin of such
behavior is explained in the framework of Landau-Ginzburg theory.Comment: 10 pages, 5 figure
First passage time for random walks in heterogeneous networks
The first passage time (FPT) for random walks is a key indicator of how fast
information diffuses in a given system. Despite the role of FPT as a
fundamental feature in transport phenomena, its behavior, particularly in
heterogeneous networks, is not yet fully understood. Here, we study, both
analytically and numerically, the scaling behavior of the FPT distribution to a
given target node, averaged over all starting nodes. We find that random walks
arrive quickly at a local hub, and therefore, the FPT distribution shows a
crossover with respect to time from fast decay behavior (induced from the
attractive effect to the hub) to slow decay behavior (caused by the exploring
of the entire system). Moreover, the mean FPT is independent of the degree of
the target node in the case of compact exploration. These theoretical results
justify the necessity of using a random jump protocol (empirically used in
search engines) and provide guidelines for designing an effective network to
make information quickly accessible.Comment: 5 pages, 3 figure
N-Triflylphosphorimidoyl Trichloride: A Versatile Reagent for the Synthesis of Strong Chiral Brønsted Acids
A series of strong Brønsted acids has been synthesized in high yields using N-triflylphosphorimidoyl trichloride as reagent. The syntheses proceed efficiently with electron-rich, electron-deficient, and sterically hindered substrates
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