1,975 research outputs found
Results from thinning experiments in 2002 and 2003
In 2002 an experiment about thinning blossoms of the apple variety 'Pinova' lime sulfur (in 2002 45
% thinning) and sodium salt (21 % thinning) showed good effects, the number of blossom-clusters
in 2003 was very high in the lime sulfur parcels. Results from extracts of Hericium erinaceum in
2003 have to be replicated again, the number of applications must be increased
Quality of a Which-Way Detector
We introduce a measure Q of the "quality" of a quantum which-way detector,
which characterizes its intrinsic ability to extract which-way information in
an asymmetric two-way interferometer. The "quality" Q allows one to separate
the contribution to the distinguishability of the ways arising from the quantum
properties of the detector from the contribution stemming from a-priori
which-way knowledge available to the experimenter, which can be quantified by a
predictability parameter P. We provide an inequality relating these two sources
of which-way information to the value of the fringe visibility displayed by the
interferometer. We show that this inequality is an expression of duality,
allowing one to trace the loss of coherence to the two reservoirs of which-way
information represented by Q and P. Finally, we illustrate the formalism with
the use of a quantum logic gate: the Symmetric Quanton-Detecton System (SQDS).
The SQDS can be regarded as two qubits trying to acquire which way information
about each other. The SQDS will provide an illustrating example of the
reciprocal effects induced by duality between system and which-way detector.Comment: 10 pages, 5 figure
Mutually unbiased bases for the rotor degree of freedom
We consider the existence of a continuous set of mutually unbiased bases for
the continuous and periodic degree of freedom that describes motion on a circle
(rotor degree of freedom). By a singular mapping of the circle to the line, we
find a first, but somewhat unsatisfactory, continuous set which does not relate
to an underlying Heisenberg pair of complementary observables. Then, by a
nonsingular mapping of the discrete angular momentum basis of the rotor onto
the Fock basis for linear motion, we construct such a Heisenberg pair for the
rotor and use it to obtain a second, fully satisfactory, set of mutually
unbiased bases.Comment: 9 pages, 4 figure
G+++ Invariant Formulation of Gravity and M-Theories: Exact BPS Solutions
We present a tentative formulation of theories of gravity with suitable
matter content, including in particular pure gravity in D dimensions, the
bosonic effective actions of M-theory and of the bosonic string, in terms of
actions invariant under very-extended Kac-Moody algebras G+++. We conjecture
that they host additional degrees of freedom not contained in the conventional
theories. The actions are constructed in a recursive way from a level expansion
for all very-extended algebras G+++. They constitute non-linear realisations on
cosets, a priori unrelated to space-time, obtained from a modified Chevalley
involution. Exact solutions are found for all G+++. They describe the algebraic
properties of BPS extremal branes, Kaluza-Klein waves and Kaluza-Klein
monopoles. They illustrate the generalisation to all G+++ invariant theories of
the well-known duality properties of string theories by expressing duality as
Weyl invariance in G+++. Space-time is expected to be generated dynamically. In
the level decomposition of E8+++ = E11, one may indeed select an A10
representation of generators Pa which appears to engender space-time
translations by inducing infinite towers of fields interpretable as field
derivatives in space and time.Comment: Latex 45 pages, 1 figure. Discussion on pages 19 and 20 altered.
Appendix B amplified. 4 footnotes added. 2 references added. Acknowledgments
updated. Additional minor correction
Abrupt and gradual changes of information through the Kane solid state computer
The susceptibility of the transformed information to the filed and system
parameters is investigated for the Kane solid state computer. It has been
shown, that the field polarization and the initial state of the system play the
central roles on the abrupt and gradual quench of the purity and the fidelity.
If the field and the initial state are in different polarizations, then the
purity and the fidelity decrease abruptly, while for the common polarization
the decay is gradual and smooth. For some class of initial states one can send
the information without any loss. Therefore, by controlling on the devices one
can increase the time of safe communication, reduce the amount of exchange
information between the state and its environment and minimize the purity
decrease rate
Interacting Bosons at Finite Temperature: How Bogolubov Visited a Black Hole and Came Home Again
The structure of the thermal equilibrium state of a weakly interacting Bose
gas is of current interest. We calculate the density matrix of that state in
two ways. The most effective method, in terms of yielding a simple, explicit
answer, is to construct a generating function within the traditional framework
of quantum statistical mechanics. The alternative method, arguably more
interesting, is to construct the thermal state as a vector state in an
artificial system with twice as many degrees of freedom. It is well known that
this construction has an actual physical realization in the quantum
thermodynamics of black holes, where the added degrees of freedom correspond to
the second sheet of the Kruskal manifold and the thermal vector state is a
state of the Unruh or the Hartle-Hawking type. What is unusual about the
present work is that the Bogolubov transformation used to construct the thermal
state combines in a rather symmetrical way with Bogolubov's original
transformation of the same form, used to implement the interaction of the
nonideal gas in linear approximation. In addition to providing a density
matrix, the method makes it possible to calculate efficiently certain
expectation values directly in terms of the thermal vector state of the doubled
system.Comment: 25 pages, LaTeX. To appear in a special issue of Foundations of
Physics in honor of Jacob Bekenstei
Mutually unbiased bases in dimension six: The four most distant bases
We consider the average distance between four bases in dimension six. The
distance between two orthonormal bases vanishes when the bases are the same,
and the distance reaches its maximal value of unity when the bases are
unbiased. We perform a numerical search for the maximum average distance and
find it to be strictly smaller than unity. This is strong evidence that no four
mutually unbiased bases exist in dimension six. We also provide a two-parameter
family of three bases which, together with the canonical basis, reach the
numerically-found maximum of the average distance, and we conduct a detailed
study of the structure of the extremal set of bases.Comment: 10 pages, 2 figures, 1 tabl
Hierarchy of inequalities for quantitative duality
We derive different relations quantifying duality in a generic two-way
interferometer. These relations set different upper bounds to the visibility V
of the fringes measured at the output port of the interferometer. A hierarchy
of inequalities is presented which exhibits the influence of the availability
to the experimenter of different sources of which-way information contributing
to the total distinguishability D of the ways. For mixed states and unbalanced
interferometers an inequality is derived, V^2+ Xi^2 \leq 1, which can be more
stringent than the one associated with the distinguishability (V^2+ D^2 \leq
1).Comment: 7 pages, 4 figure
On Visibility in the Afshar Two-Slit Experiment
A modified version of Young's experiment by Shahriar Afshar indirectly
reveals the presence of a fully articulated interference pattern prior to the
post-selection of a particle in a "which-slit" basis. While this experiment
does not constitute a violation of Bohr's Complementarity Principle as claimed
by Afshar, both he and many of his critics incorrectly assume that a commonly
used relationship between visibility parameter V and "which-way" parameter K
has crucial relevance to his experiment. It is argued here that this
relationship does not apply to this experimental situation and that it is wrong
to make any use of it in support of claims for or against the bearing of this
experiment on Complementarity.Comment: Final version; to appear in Foundations of Physic
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