43,352 research outputs found

### Optimal conclusive discrimination of two states can be achieved locally

This paper constructs a LOCC protocol that achieves the global optimality in
conclusive discrimination of any two states with arbitrary a priori
probability. This can be interpreted that there is no ``non-locality'' in the
conclusive discrimination of two multipartite states.Comment: 9 pages, RevTeX, no figure. Comments, criticisms and suggestions are
welcom

### Kappa - Poincare dispersion relations and the black hole radiation

Following the methods developed by Corley and Jacobson, we consider
qualitatively the issue of Hawking radiation in the case when the dispersion
relation is dictated by quantum kappa-Poincare algebra. This relation
corresponds to field equations that are non-local in time, and, depending on
the sign of the parameter kappa, to sub- or superluminal signal propagation. We
also derive the conserved inner product, that can be used to count modes, and
therefore to obtain the spectrum of black hole radiation in this case.Comment: 11 pages, 2 figure

### Infinite Infrared Regularization and a State Space for the Heisenberg Algebra

We present a method for the construction of a Krein space completion for
spaces of test functions, equipped with an indefinite inner product induced by
a kernel which is more singular than a distribution of finite order. This
generalizes a regularization method for infrared singularities in quantum field
theory, introduced by G. Morchio and F. Strocchi, to the case of singularites
of infinite order. We give conditions for the possibility of this procedure in
terms of local differential operators and the Gelfand- Shilov test function
spaces, as well as an abstract sufficient condition. As a model case we
construct a maximally positive definite state space for the Heisenberg algebra
in the presence of an infinite infrared singularity.Comment: 18 pages, typos corrected, journal-ref added, reference adde

### Why Nature has made a choice of one time and three space coordinates?

We propose a possible answer to one of the most exciting open questions in
physics and cosmology, that is the question why we seem to experience four-
dimensional space-time with three ordinary and one time dimensions. We have
known for more than 70 years that (elementary) particles have spin degrees of
freedom, we also know that besides spin they also have charge degrees of
freedom, both degrees of freedom in addition to the position and momentum
degrees of freedom. We may call these ''internal degrees of freedom '' the
''internal space'' and we can think of all the different particles, like quarks
and leptons, as being different internal states of the same particle. The
question then naturally arises: Is the choice of the Minkowski metric and the
four-dimensional space-time influenced by the ''internal space''?
Making assumptions (such as particles being in first approximation massless)
about the equations of motion, we argue for restrictions on the number of space
and time dimensions. (Actually the Standard model predicts and experiments
confirm that elementary particles are massless until interactions switch on
masses.)
Accepting our explanation of the space-time signature and the number of
dimensions would be a point supporting (further) the importance of the
''internal space''.Comment: 13 pages, LaTe

### On the Generality of Refined Algebraic Quantization

The Dirac quantization `procedure' for constrained systems is well known to
have many subtleties and ambiguities. Within this ill-defined framework, we
explore the generality of a particular interpretation of the Dirac procedure
known as refined algebraic quantization. We find technical conditions under
which refined algebraic quantization can reproduce the general implementation
of the Dirac scheme for systems whose constraints form a Lie algebra with
structure constants. The main result is that, under appropriate conditions, the
choice of an inner product on the physical states is equivalent to the choice
of a ``rigging map'' in refined algebraic quantization.Comment: 12 pages, no figures, ReVTeX, some changes in presentation, some
references adde

### Resonance-Based microwave technique for body implant sensing

There is an increasing need for safe and simple techniques for sensing devices and prostheses implanted inside the human body. Microwave wireless inspection may be an appropriate technique for it. The implanted device may have specific characteristics that allow to distinguish it from its environment. A new sensing technique based on the principle of differential resonance is proposed and its basic parameters are discussed. This technique allows to use the implant as a signal scattering device and to detect changes produced in the implant based on the corresponding change in its scattering signature. The technique is first tested with a canonic human phantom and then applied to a real in vivo clinical experiment to detect coronary stents implanted in swine animalsPeer ReviewedPostprint (published version

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