18 research outputs found
Preparation of entangled states of two photons in several spatial modes
We describe a protocol capable of preparing an arbitrary state of two photons
in several spatial modes using pairs of photons generated by spontaneous
parametric down-conversion, linear optical elements and single-photon detectors
or post-selection. The protocol involves unitary and non-unitary
transformations realizable by beam splitters and phase shifters. Non-unitary
transformations are implemented by attenuation filters. The protocol contains
several optimization capabilities with the goal of improving overall
probability of its success. We also show how entangled two-photon states
required for quantum computing with linear optics can be prepared using a very
simple and feasible scheme.Comment: 9 pages, 9 figures, REVTeX
DNA barcoding, dwelling morphology, and fecundity of the gall-forming shrimp <i>Paratypton siebenrocki</i> Balss, 1914 (Caridea: Palaemonidae)
Tropical coral reefs offer a wide variety of habitats to countless invertebrate species. Sessile host organisms especially are inhabited by small taxa, of which decapod crustaceans form one of the most diverse communities. Symbiotic palaemonid shrimp species associ-ate with marine invertebrate hosts from multiple phyla, including cnidarians such as stony corals (Scleractinia). The intriguing gall- forming shrimp Paratypton siebenrocki, a symbiont of Acropora corals in the Indo-Pacific, was collected in the Saudi Arabian Red Sea, Kenya, and the Maldives. Based on morphology P. siebenrocki has been considered to be most closely related to the genera Anapontonia and Metapontonia; however, no clear clustering with either palaemonid genus was observed in a phylogenetic recon-struction based on 16S and COI mtDNA. Here we photo-document the dwellings of P. siebenrocki in Acropora spp. for the first time, and furthermore we report on the reproductive output of this species. The number of eggs ranged from 345 to 909 (n = 6), and embryo volume differed strongly between early- and late-stage embryos. The carapace length ranged from 2.58 to 4.55 mm for the females and 1.51 to 2.5 mm for the males (n = 5). The number and size of the embryos, combined with their specialised, secluded lifestyle, sug-gest that P. siebenrocki allocates highe
Classical Teleportation of a Quantum Bit
Classical teleportation is defined as a scenario where the sender is given
the classical description of an arbitrary quantum state while the receiver
simulates any measurement on it. This scenario is shown to be achievable by
transmitting only a few classical bits if the sender and receiver initially
share local hidden variables. Specifically, a communication of 2.19 bits is
sufficient on average for the classical teleportation of a qubit, when
restricted to von Neumann measurements. The generalization to
positive-operator-valued measurements is also discussed.Comment: 4 pages, RevTe
Preparation of Knill-Laflamme-Milburn states using tunable controlled phase gate
A specific class of partially entangled states known as
Knill-Laflamme-Milburn states (or KLM states) has been proved to be useful in
relation to quantum information processing [Knill et al., Nature 409, 46
(2001)]. Although the usage of such states is widely investigated, considerably
less effort has been invested into experimentally accessible preparation
schemes. This paper discusses the possibility to employ a tunable controlled
phase gate to generate an arbitrary Knill-Laflamme-Milburn state. In the first
part, the idea of using the controlled phase gate is explained on the case of
two-qubit KLM states. Optimization of the proposed scheme is then discussed for
the framework of linear optics. Subsequent generalization of the scheme to
arbitrary n-qubit KLM state is derived in the second part of this paper.Comment: 5 pages, 4 figures, accepted in Journal of Physics
Tunneling Violates Special Relativity
Experiments with evanescent modes and tunneling particles have shown that i)
their signal velocity may be faster than light, ii) they are described by
virtual particles, iii) they are nonlocal and act at a distance, iv)
experimental tunneling data of phonons, photons, and electrons display a
universal scattering time at the tunneling barrier front, and v) the properties
of evanescent, i.e. tunneling modes is not compatible with the special theory
of relativity
Entanglement, local measurements, and symmetry
A definition of entanglement in terms of local measurements is discussed.
Viz, the maximum entanglement corresponds to the states that cause the highest
level of quantum fluctuations in all local measurements determined by the
dynamic symmetry group of the system. A number of examples illustrating this
definition is considered.Comment: 10 pages. to be published in Journal of Optics
Basics of Superluminal Signals
The paper elucidates the physical basis of experimental results on
superluminal signal velocity. It will be made plausible that superluminal
signals do not violate the principle of causality but they can shorten the
luminal vacuum time span between cause and effect. This amazing behaviour is
based on the property that any physical signal has a finite duration.Comment: 11 pages, 8 figure
DNA barcoding, dwelling morphology, and fecundity of the gall-forming shrimp Paratypton siebenrocki Balss, 1914 (Caridea: Palaemonidae)
Tropical coral reefs offer a wide variety of habitats to countless invertebrate species. Sessile host organisms especially are inhabited by small taxa, of which decapod crustaceans form one of the most diverse communities. Symbiotic palaemonid shrimp species associ-ate with marine invertebrate hosts from multiple phyla, including cnidarians such as stony corals (Scleractinia). The intriguing gall- forming shrimp Paratypton siebenrocki, a symbiont of Acropora corals in the Indo-Pacific, was collected in the Saudi Arabian Red Sea, Kenya, and the Maldives. Based on morphology P. siebenrocki has been considered to be most closely related to the genera Anapontonia and Metapontonia; however, no clear clustering with either palaemonid genus was observed in a phylogenetic recon-struction based on 16S and COI mtDNA. Here we photo-document the dwellings of P. siebenrocki in Acropora spp. for the first time, and furthermore we report on the reproductive output of this species. The number of eggs ranged from 345 to 909 (n = 6), and embryo volume differed strongly between early- and late-stage embryos. The carapace length ranged from 2.58 to 4.55 mm for the females and 1.51 to 2.5 mm for the males (n = 5). The number and size of the embryos, combined with their specialised, secluded lifestyle, sug-gest that P. siebenrocki allocates highe
Induced plant volatiles allow sensitive monitoring of plant health status in greenhouses
This paper provides a synthesis of our research on the use of induced plant volatiles for sensitive monitoring of plant health status in greenhouses. The main research objective of this research was to investigate whether plant-emitted volatiles can be used to detect a Botrytis cinerea infection in a large-scale greenhouse. The pathogenic fungus B. cinerea and the plant species tomato (Lycopersicon esculentum) were selected as model organisms. Based on this choice, three main research questions were formulated: (1) What is the effect of a B. cinerea infection on the emission of volatiles from tomato? (2) Are B. cinerea induced emissions of tomato specific for the infection with this pathogen? (3) Are B. cinerea induced concentrations of volatiles detectable in large-scale greenhouses