46 research outputs found
Tailoring Single and Multiphoton Probabilities of a Single Photon On-Demand Source
As typically implemented, single photon sources cannot be made to produce
single photons with high probability, while simultaneously suppressing the
probability of yielding two or more photons. Because of this, single photon
sources cannot really produce single photons on demand. We describe a
multiplexed system that allows the probabilities of producing one and more
photons to be adjusted independently, enabling a much better approximation of a
source of single photons on demand.Comment: 4 pages, LaTex, 2 figures, twocolumn and RevTex Style for PR
Engineering Entanglement between two cavity modes
We present scheme for generation of entanglement between different modes of
radiation field inside high-Q superconducting cavities. Our scheme is based on
the interaction of a three-level atom with the cavity field for pre-calculated
interaction times with each mode. This work enables us to generate complete set
of Bell basis states and GHZ state
Quantum and Classical Noise in Practical Quantum Cryptography Systems based on polarization-entangled photons
Quantum-cryptography key distribution (QCKD) experiments have been recently
reported using polarization-entangled photons. However, in any practical
realization, quantum systems suffer from either unwanted or induced
interactions with the environment and the quantum measurement system, showing
up as quantum and, ultimately, statistical noise. In this paper, we investigate
how ideal polarization entanglement in spontaneous parametric downconversion
(SPDC) suffers quantum noise in its practical implementation as a secure
quantum system, yielding errors in the transmitted bit sequence. Because all
SPDC-based QCKD schemes rely on the measurement of coincidence to assert the
bit transmission between the two parties, we bundle up the overall quantum and
statistical noise in an exhaustive model to calculate the accidental
coincidences. This model predicts the quantum-bit error rate and the sifted key
and allows comparisons between different security criteria of the hitherto
proposed QCKD protocols, resulting in an objective assessment of performances
and advantages of different systems.Comment: Rev Tex Style, 2 columns, 7 figures, (a modified version will appear
on PRA
Disk-cylinder method for using NMR to measure magnetic susceptibility
The sphere-cylinder method of using nuclear magnetic resonance (NMR) to measure the magnetic susceptibility of diamagnetic and paramagnetic materials has been generalized to the disk-cylinder method. A two-fold increase in sensitivity was obtained. Accuracies of 0.1% of the diamagnetism of water should be readily obtainable
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Polymers replace glass in Nova fuel capsules
The glass fuel-capsule designs used in previous laser-fusion research are not adaptable to the implosion-physics requirements of Nova and other more powerful laser facilities that may be available in the future. As one tries to learn more about the physics of high-density compression, it becomes increasingly important to replace the glass with lower-Z material. Accordingly, the authors have shut down the high-temperature drop-tower furnaces they used to make glass capsules, and they are focusing all their efforts on developing new techniques for making polymer capsules. These capsules are ten times larger in diameter than the glass capsules used in the early days of laser-fusion research, but they are still only one-tenth as large as a high-gain capsule must be. The polymer capsules will be used in classified indirect-drive targets. This article describes how the decisions were made on which polymers to use in the NOVA fuel capsules, the techniques explored, and the properties of the prototype capsules
Colloidal interactions and transport in nematic liquid crystals
We describe a new nematic liquid-crystal colloid system which is characterized by both charge stabilization of the particles and an interaction force. We estimate the effective charge of the particles by electrophoretic measurements and find that in such systems the director anchoring energy W is very low and the particles have little director distortion around them. The interaction force is created by producing a radial distribution of the nematic order parameter around a locally isotropic region created by ir laser heating. We theoretically describe this as being due to the induced flexoelectric polarization, the quadrupolar symmetry of which provides the required long-range force acting on charged particles
ICTAC Kinetics Committee recommendations for performing kinetic computations on thermal analysis data
The present recommendations have been developed by the Kinetics Committee of the International Confederation for Thermal Analysis and Calorimetry (ICTAC). The recommendations offer guidance for reliable evaluation of kinetic parameters (the activation energy, the pre-exponential factor, and the reaction model) from the data obtained by means of thermal analysis methods such as thermogravimetry (TGA), differential scanning calorimetry (DSC), and differential thermal analysis (DTA). The recommendations cover the most common kinetic methods, model-free (isoconversional) as well as model-fitting. The focus is on the problems faced by various kinetic methods and on the ways how these problems can be resolved. Recommendations on making reliable kinetic predictions are also provided. The objective of these recommendations is to help a non-expert with efficiently performing analysis and interpreting its results. © 2011 Elsevier B.V.The authors thank all their colleagues who actively participated in the discussions of the present project during the 14th ICTAC Congress, 37th NATAS Conference, and 10th ESTAC Conference. Special thanks are due to those who invested the time and effort to provide written comments: Petru Budrugeac, Konstantinos Chrissafis, John Curtis, Jordi Farjas, Nobuyoshi Koga, Vesa-Pekka Lehto, Vladimir Logvinenko, Jiri Málek, Michele Pijolat, Bertrand Roduit, Andrei Rotaru, Marco Starink, and Gábor Várhegyi. An apology is due for not being able to accommodate the suggestions to a greater extent.Peer Reviewe