14,443 research outputs found
Theory of impedance networks: The two-point impedance and LC resonances
We present a formulation of the determination of the impedance between any
two nodes in an impedance network. An impedance network is described by its
Laplacian matrix L which has generally complex matrix elements. We show that by
solving the equation L u_a = lambda_a u_a^* with orthonormal vectors u_a, the
effective impedance between nodes p and q of the network is Z = Sum_a [u_{a,p}
- u_{a,q}]^2/lambda_a where the summation is over all lambda_a not identically
equal to zero and u_{a,p} is the p-th component of u_a. For networks consisting
of inductances (L) and capacitances (C), the formulation leads to the
occurrence of resonances at frequencies associated with the vanishing of
lambda_a. This curious result suggests the possibility of practical
applications to resonant circuits. Our formulation is illustrated by explicit
examples.Comment: 21 pages, 3 figures; v4: typesetting corrected; v5: Eq. (63)
correcte
Entanglement in spin chains and lattices with long-range Ising-type interactions
We consider N initially disentangled spins, embedded in a ring or
d-dimensional lattice of arbitrary geometry, which interact via some
long--range Ising--type interaction. We investigate relations between
entanglement properties of the resulting states and the distance dependence of
the interaction in the limit N to infinity. We provide a sufficient condition
when bipartite entanglement between blocks of L neighboring spins and the
remaining system saturates, and determine S_L analytically for special
configurations. We find an unbounded increase of S_L as well as diverging
correlation and entanglement length under certain circumstances. For
arbitrarily large N, we can efficiently calculate all quantities associated
with reduced density operators of up to ten particles.Comment: 4 pages, 2 figures; V2: presentation improved, references adde
Investigating the timecourse of accessing conversational implicatures during incremental sentence interpretation
Many contextual inferences in utterance interpretation are explained as following from the nature of conversation and the assumption that participants are rational. Recent psycholinguistic research has focussed on certain of these âGriceanâ inferences and have revealed that comprehenders can access them in online interpretation. However there have been mixed results as to the time-course of access. Some results show that Gricean inferences can be accessed very rapidly, as rapidly as any other contextually specified information (Sedivy, 2003; Grodner, Klein, Carbery, & Tanenhaus, 2010); while other studies looking at the same kind of inference suggest that access to Gricean inferences are delayed relative to other aspects of semantic interpretation (Huang & Snedeker, 2009; in press). While previous timecourse research has focussed on Gricean inferences that support the online assignment of reference to definite expressions, the study reported here examines the timecourse of access to scalar implicatures, which enrich the meaning of an utterance beyond the semantic interpretation. Even if access to Gricean inference in support of reference assignment may be rapid, it is still unknown whether genuinely enriching scalar implicatures are delayed. Our results indicate that scalar implicatures are accessed as rapidly as other contextual inferences. The implications of our results are discussed in reference to the architecture of language comprehension
Serodiagnosis of infectious mononucleosis by using recombinant Epstein-Barr virus antigens and enzyme-linked immunosorbent assay technology
Four recombinant, diagnostically useful Epstein-Barr virus (EBV) proteins representative of the viral capsid antigen (p150), diffuse early antigen (p54), the major DNA-binding protein (p138), and the EBV nuclear antigen (p72) (W. Hinderer, H. Nebel-Schickel, H.H. Sonneborn, M. Motz, R. KĂŒhbeck, and H. Wolf, J. Exp. Clin. Cancer Res. 7[Suppl.]:132, 1988) were used to set up individual enzyme-linked immunosorbent assays (ELISAs) for the qualitative and quantitative detection of immunoglobulin M (IgM) and IgG antibodies. In direct comparison with results obtained by standard immunofluorescence or immunoperoxidase assays, it was then shown that the recombinant EBV ELISAs provide the means for specific and sensitive serodiagnosis of infectious mononucleosis (IM) caused by EBV. The most useful markers in sera from such patients proved to be IgM antibodies against p54, p138, and p150. Additional positive markers for recent or ongoing IM apparently were IgG antibodies against p54 and p138. In contrast, anti-p72 IgG had a high preference for sera from healthy blood donors and, therefore, can be considered indicative of past exposure to the virus. Altogether, the individual ELISAs proved to be as specific and at least as sensitive for the diagnosis of IM as the currently available standard techniques are. Moreover, our findings suggest that, by combining individual test antigens, a workable ELISA system consisting of three assays (IgM against p54, p138, and p150; IgG against p54 and p138; and IgG against p72) can be established for the standardized rapid diagnosis of acute EBV infections
Quantum authentication with unitary coding sets
A general class of authentication schemes for arbitrary quantum messages is
proposed. The class is based on the use of sets of unitary quantum operations
in both transmission and reception, and on appending a quantum tag to the
quantum message used in transmission. The previous secret between partners
required for any authentication is a classical key. We obtain the minimal
requirements on the unitary operations that lead to a probability of failure of
the scheme less than one. This failure may be caused by someone performing a
unitary operation on the message in the channel between the communicating
partners, or by a potential forger impersonating the transmitter.Comment: RevTeX4, 10 page
Compatibility Relations between the Reduced and Global Density Matrixes
It is a hard and important problem to find the criterion of the set of
positive-definite matrixes which can be written as reduced density operators of
a multi-partite quantum state. This problem is closely related to the study of
many-body quantum entanglement which is one of the focuses of current quantum
information theory. We give several results on the necessary compatibility
relations between a set of reduced density matrixes, including: (i)
compatibility conditions for the one-party reduced density matrixes of any
dimensional bi-partite mixed quantum state, (ii) compatibility
conditions for the one-party and two-party reduced density matrixes of any
dimensional tri-partite mixed quantum state, and
(iii) compatibility conditions for the one-party reduced matrixes of any
-partite pure quantum state with the dimension .Comment: 14 page
Gaussian Entanglement of Formation
We introduce a Gaussian version of the entanglement of formation adapted to
bipartite Gaussian states by considering decompositions into pure Gaussian
states only. We show that this quantity is an entanglement monotone under
Gaussian operations and provide a simplified computation for states of
arbitrary many modes. For the case of one mode per site the remaining
variational problem can be solved analytically. If the considered state is in
addition symmetric with respect to interchanging the two modes, we prove
additivity of the considered entanglement measure. Moreover, in this case and
considering only a single copy, our entanglement measure coincides with the
true entanglement of formation.Comment: 8 pages (references updated, typos corrected
Equivalence of particle-particle random phase approximation correlation energy and ladder-coupled-cluster doubles
We present an analytical proof and numerical demonstrations of the
equivalence of the correlation energy from particle-particle random phase
approximation (pp-RPA) and ladder-couple-cluster-doubles (ladder-CCD). These
two theories reduce to the identical algebraic matrix equation and correlation
energy expressions, under the assumption that the pp-RPA equation is stable.
The numerical examples illustrate that the correlation energy missed by pp-RPA
in comparison with couple-cluster single and double is largely canceled out
when considering reaction energies. This theoretical connection will be
beneficial to future pp-RPA studies based on the well established couple
cluster theory
- âŠ