oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2018 ( 1 )

2016 ( 1 )

2015 ( 11 )

2014 ( 18 )

Custom range...

Search Results: 1 - 10 of 302 matches for " Yehuda Sharf "
All listed articles are free for downloading (OA Articles)
Page 1 /302
Display every page Item
Quantum Codes for Controlling Coherent Evolution
Yehuda Sharf,Timothy F. Havel,David G. Cory
Physics , 2000, DOI: 10.1063/1.1326071
Abstract: Control over spin dynamics has been obtained in NMR via coherent averaging, which is implemented through a sequence of RF pulses, and via quantum codes which can protect against incoherent evolution. Here, we discuss the design and implementation of quantum codes to protect against coherent evolution. A detailed example is given of a quantum code for protecting two data qubits from evolution under a weak coupling (Ising) term in the Hamiltonian, using an ``isolated'' ancilla which does not evolve on the experimental time scale. The code is realized in a three-spin system by liquid-state NMR spectroscopy on 13C-labelled alanine, and tested for two initial states. It is also shown that for coherent evolution and isolated ancillae, codes exist that do not require the ancillae to initially be in a (pseudo-)pure state. Finally, it is shown that even with non-isolated ancillae quantum codes exist which can protect against evolution under weak coupling. An example is presented for a six qubit code that protects two data spins to first order.
Spatially Encoded Pseudo-Pure States for NMR Quantum Information Processing
Yehuda Sharf,Timothy F. Havel,David G. Cory
Physics , 2000, DOI: 10.1103/PhysRevA.62.052314
Abstract: Quantum information processing by liquid-state NMR spectroscopy uses pseudo-pure states to mimic the evolution and observations on true pure states. A new method of preparing pseudo-pure states is described, which involves the selection of the spatially labeled states of an ancilla spin with which the spin system of interest is correlated. This permits a general procedure to be given for the preparation of pseudo-pure states on any number of spins, subject to the limitations imposed by the loss of signal from the selected subensemble. The preparation of a single pseudo-pure state is demonstrated by carbon and proton NMR on 13C-labeled alanine. With a judicious choice of magnetic field gradients, the method further allows encoding of up to 2^N pseudo-pure states in independent spatial modes in an N+1 spin system. Fast encoding and decoding schemes are demonstrated for the preparation of four such spatially labeled pseudo-pure states.
Hadamard Products of Product Operators and the Design of Gradient-Diffusion Experiments for Simulating Decoherence by NMR Spectroscopy
Timothy F. Havel,Yehuda Sharf,Lorenza Viola,David G. Cory
Physics , 2000, DOI: 10.1016/S0375-9601(01)00083-4
Abstract: An extension of the product operator formalism of NMR is introduced, which uses the Hadamard matrix product to describe many simple spin 1/2 relaxation processes. The utility of this formalism is illustrated by deriving NMR gradient-diffusion experiments to simulate several decoherence models of interest in quantum information processing, along with their Lindblad and Kraus representations. Gradient-diffusion experiments are also described for several more complex forms of decoherence, including the well-known collective isotropic model. Finally, it is shown that the Hadamard formalism gives a concise representation of decoherence with arbitrary correlations among the fluctuating fields at the different spins involved, and that this can be applied to both decoherence (T2) as well as nonadiabatic relaxation (T1) processes.
A Study of Quantum Error Correction by Geometric Algebra and Liquid-State NMR Spectroscopy
Yehuda Sharf,David G. Cory,Shyamal S. Somaroo,Timothy F. Havel,Emanuel Knill,Raymond Laflamme
Physics , 2000, DOI: 10.1080/002689700413604
Abstract: Quantum error correcting codes enable the information contained in a quantum state to be protected from decoherence due to external perturbations. Applied to NMR, quantum coding does not alter normal relaxation, but rather converts the state of a ``data'' spin into multiple quantum coherences involving additional ancilla spins. These multiple quantum coherences relax at differing rates, thus permitting the original state of the data to be approximately reconstructed by mixing them together in an appropriate fashion. This paper describes the operation of a simple, three-bit quantum code in the product operator formalism, and uses geometric algebra methods to obtain the error-corrected decay curve in the presence of arbitrary correlations in the external random fields. These predictions are confirmed in both the totally correlated and uncorrelated cases by liquid-state NMR experiments on 13C-labeled alanine, using gradient-diffusion methods to implement these idealized decoherence models. Quantum error correction in weakly polarized systems requires that the ancilla spins be prepared in a pseudo-pure state relative to the data spin, which entails a loss of signal that exceeds any potential gain through error correction. Nevertheless, this study shows that quantum coding can be used to validate theoretical decoherence mechanisms, and to provide detailed information on correlations in the underlying NMR relaxation dynamics.
The Schrödinger Equation of the Hilbert Hyper Space  [PDF]
Yehuda Roth
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.42023
Abstract:

Quantum measurement requires an observer to prepare a specific macroscopic measuring device from various options. In previous papers we redefined this observer role through a new concept: the observer determination, that is, the observers unique selection between the various measurement-devices. Unlike the measurement itself that is rationalized as dictated by nature, we presented the observer determination as a selection that cannot be disputed since it can neither be measured nor proven to be true or false. In general, we suggest that every action or decision made by the observer is eventually an output of some measurement. The apparently contradiction between the observer free determination and the deterministic measurement output was solved by extending the Hilbert space into a Hyper Hilbert space that is a space with hierarchy. In that frame the so called free selection of the observer determination in a certain level turns out to be a deterministic measurement output in the next higher level of the hierarchy. An important role of the conventional Hilbert space is played by the Schr?dinger equation. It determines a basis of stationary states. In this paper we define the Schr?dinger equation that corresponds with the various levels and we show that each level can be characterized by a unique time scale. We also show how various levels can be synchronized. We believe that this hyperspace level represents a certain level in the physics of consciousness and therefore a level unique time scale can contribute to the time perception of the mind.

Bifurcation and Pattern Recognition  [PDF]
Yehuda Roth
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.41005
Abstract: We propose a new approach in dealing with image recognition. We suggest that recognizing an image is related to the knowledge of a pure quantum state. Since most images are screened through incoherent photons, we introduce a method base on non-linear mapping iterations to regenerate coherence between the image photons.
Single Measurement of Figures  [PDF]
Yehuda Roth
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.46111
Abstract:

We introduce a new approach in dealing with pattern recognition issue. Recognizing a pattern is definitely not the exploration of a new discovery but rather the search for already known patterns. In reading for example the same text written in a hand writing, letters can appear in different shapes. Still, the text decoding corresponds with interpreting the large variety of hand writings shapes with fonts. Quantum mechanics also offer a kind of interpretation tool. Although, with the superposition principle it is possible to compose an infinite number of states, yet, an observer by conducting a measurement reduces the number of observed states into the predetermined basis states. Not only that any state collapses into one of the basis states, quantum mechanics also possesses a kind of correction mechanism in a sense that if the measured state is close enough to one of the basis states, it will collapse with high probability into this predetermined state. Thus, we can consider the collapse mechanism as a reliable way for the observer to interpret reality into his frame of concepts. Both interpretation ideas, pattern recognition and quantum measurement are integrated in this paper to formulate a quantum pattern recognition measuring procedure.

Rapid Quantum Search Algorithm  [PDF]
Yehuda Roth
Journal of Modern Physics (JMP) , 2013, DOI: 10.4236/jmp.2013.49158
Abstract:

The collapse phenomenon, the parallelism principle and states correlation are used to define a type of a Grover rapid search engine. In our approach, the observer’s query and the Grover-unsorted-data are stored in different memories where the global state is represented by a tensor product of the associated states. In the proposed formalism, each query-state input activates an adjusted operator that implements the unsorted state in an appropriate 2-D Grover representation. It will be shown that once the representation is set, it takes mainly two operations to complete the whole query search. This seems to be a very efficient search algorithm.

Homeostasis Processes Expressed as Flashes in a Poincaré Sections  [PDF]
Yehuda Roth
Journal of Modern Physics (JMP) , 2018, DOI: 10.4236/jmp.2018.912134
Abstract: We describe a homeostasis system with a discrete map that is revealed by stroboscopic “flashes” (Poincaré sections) that are synchronized with the measurement events.
Trace Elements Assessment in Human Nails in Eastern Sudan Using Atomic Absorption Spectroscopy  [PDF]
Salwa M. Salwa M. Ibrahim, Abdelrazig M. Abdelbagi, ALi E. Sharf ALi E. Sharf Eldeen
Journal of Analytical Sciences, Methods and Instrumentation (JASMI) , 2014, DOI: 10.4236/jasmi.2014.41001
Abstract:

In the present work, elements concentration in fingernails samples of volunteers of different ages (males, females) were determined using atomic absorption spectroscopy (AAS) Perkin-Elmer, spectrophotometer. Fingernails samples of different groups were analyzed to determine the trace elements Ca, Mg, Mn, Fe, Ni, Cu, Co, Zn and Pb. Standards materials were prepared for concentration assessment that adjacent to samples from two cities in different location in eastern province of Sudan for elements concentrations finding. In addition, samples of hands fingernails and toenails were analyzed for comparison and method validation. Consequently, the significant levels of elements concentration in nails samples of Jabiat residents compared to Port Sudan resident’s area due to soil dispersion are supporting the possibility of external contamination. The data of component matrix and rotated component matrix of varimax normalization using principal component analysis revealed important predictors of nails elements Mg, Mn, Fe, Cu and Zn concentrations in soil of both areas under study. However, the Pb, Ni, Ca, and Co are possible to be indication of different sources associated with environmental contamination. The significant correlation and principal component analysis of the elements of nails concentrations in the two categories supported the probability of different expose environmental contamination.


Page 1 /302
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.