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Topic: Quantum information

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	Quantum information - Wikipedia, the free encyclopedia
		In quantum mechanics, quantum information is physical information that is held in the "state" of a quantum system.
		Quantum information processing is the most general field that is concerned with quantum information.
		Quantum information, and changes in quantum information, can be quantitatively measured by using an analogue of Shannon entropy.
	en.wikipedia.org /wiki/Quantum_information (455 words)

	Quantum information science - Wikipedia, the free encyclopedia
		Quantum computing, which deals on the one hand with the question how and whether one can build a quantum computer and on the other hand, searching algorithms that harness its power (see quantum algorithm)
		Quantum teleportation is one well-known quantum information processing operation which reliably transfers an unknown quantum state from one point to another distant point, destroying the original state in the process.
		The quantum information group at the University of Leeds is engaged in researching a wide spectrum of aspects of quantum information.
	en.wikipedia.org /wiki/Quantum_information_processing (252 words)

	MagiQ Technologies
		Moreover, the superposition principle is the basis for the quantum phenomenon of entanglement which is of particular importance for quantum communication.
		Several applications of quantum mechanics to communication problems have been proposed, ranging from more efficient ways of sending classical information (dense coding) over algorithms that reduce the complexity of communication problems to novel ways to achieve secret communication.
		To design a quantum interface it is required to find a physical process that maps the internal quantum state of, e.g., an ion onto the state of the light field and vice versa.
	www.magiqtech.com /products/whatisqip.php (2944 words)

	Quantum information can be negative (popular description) (Site not responding. Last check: 2007-10-14)
		In information theory, we are unable to deal with understanding the content of information, we just worry about how much information there is. So, if Alice tells Bob something, we don't know how to quantify the value of what she is saying, just how much she says.
		A quantum ball can be completely isolated from anything which might record a memory of its colour (it is not just you who might have a memory of their colour, a ray of light which touches them can have a record of their colour).
		Quantum balls can be kept completely isolated so that no light touches them, and there is no record of their colour.
	www.damtp.cam.ac.uk /user/jono/negative-information.html (3070 words)

	Quantum Entanglement and Information
		The puzzle is that the quantum state of the particle pair is inconsistent with the assignment of labels to the particles separately that could be associated with appropriately correlated values for the outcomes of position and momentum measurements.
		The unit of quantum information is the ‘qubit’, representing the amount of quantum information that can be stored in the state of the simplest quantum system, for example, the polarization state of a photon.
		The impossibility of copying an unknown quantum state, or a state that is known to belong to a set of nonorthogonal states with a certain probability, and the existence of a trade-off relation between information gain and state disturbance, is the basis of the application of quantum information to cryptography.
	plato.stanford.edu /entries/qt-entangle (5628 words)

	Quantum information can be negative
		Negative information is due to exotic features of quantum information theory, an exciting new area of physics which includes such phenomena as quantum teleportation and quantum computation.
		Quantum information on the other hand, replaces classical ‘bits’ by quantum ‘qubits’ which are quantum particles like electrons or atoms.
		By understanding that quantum information can be negative, researchers hope to gain deeper insights into phenomena such as quantum teleportation and computation, as well as the very structure of the quantum world.
	www.physorg.com /news5621.html (1128 words)

	Quantum Information Physics, Physics Department, University of Illinois at Urbana-Champaign
		Quantum information science is the study of the often-bizarre-seeming features of quantum mechanics and their application to problems in information processing.
		By studying the full range, from single spins to small clusters of spins (in quantum dots), to large current loops in superconductors, they are attempting to assess the relative merit of different techniques, and determine the physical size limits for magnetic systems acting as qubits.
		In all quantum cryptography schemes to date, there is a necessary upper limit to the efficiency of the scheme, i.e., at most 50 percent of the photons sent can contribute to the final key.
	www.physics.uiuc.edu /Research/QI (1235 words)

	CLASSICAL and QUANTUM INFORMATION THEORY
		Information is the underlying basis of the Quantum Consciousness of All Life in ALL SPACES.
		Quantum Computing and Information Theory, a promising New Technology, is based on the Galois field GF(4) = {0,1,w,w^2} where w = (1/2)(- 1 + sqrt(3) i) and w^2 = (1/2)(- 1 - sqrt(3) i).
		In quantum information theory, Cerf and Adami describe virtual qubit-anti-qubit pairs (they call them ebit-anti-ebit pairs) that are related to negative conditional entropies for quantum entangled systems and are similar to fermion particle-antiparticle pairs of particle physics.
	www.valdostamuseum.org /hamsmith/info.html (6749 words)

	An introduction to Quantum Computing
		The simulation of a quantum computer on a classical one is a computationally hard problem because the correlations among quantum bits are qualitatively different from correlations among classical bits, as first explained by John Bell.
		The answer is primarily those errors that arise as a direct result of decoherence, or the tendency of a quantum computer to decay from a given quantum state into an incoherent state as it interacts, or entangles, with the state of the environment.
		Quantum hardware, on the other hand, remains an emerging field, but the work done thus far suggests that it will only be a matter time before we have devices large enough to test Shor's and other quantum algorithms.
	www.cs.caltech.edu /~westside/quantum-intro.html (3038 words)

	Quantum Information Theory (Site not responding. Last check: 2007-10-14)
		It is assumed that the reader has a basic understanding of quantum mechanics.
		Here are a list of topics in quantum information theory, presented in the order in which you will probably need to read them.
		All logarithms in the text are to the base 2, so that information is measured in units of bits.
	members.aol.com /jmtsgibbs/infothry.htm (162 words)

	Physics 219 Course Information
		Quantum Computation and Quantum Information by Michael Nielsen and Isaac Chuang, will be available in the fall of 2000.
		Information is something that can be encoded in the state of a physical system, and a computation is a task that can be performed with a physically realizable device.
		In fact, quantum information -- information stored in the quantum state of a physical system -- has weird properties that contrast sharply with the familiar properties of "classical" information.
	theory.caltech.edu /people/preskill/ph229 (1043 words)

	NIST: Physics Laboratory's - Quantum Information
		The starting point for quantum information at NIST was in 1995 when the Ion Storage Group demonstrated the first quantum-logic gate.
		Quantum Computers May Be Easier to Build Than Predicted, NIST Work Suggests.
		This effort entitled A Scalable Quantum Information Network is led by Carl Williams and includes representatives of the Electronics and Electrical Engineering Laboratory, the Information Technology Laboratory, and the Physics Laboratory.
	qubit.nist.gov (990 words)

	Quantum Information Dynamics
		In quantum information dynamics (1,3,7), we are trying to understand the basic principles of quantum Information Theory and its application to processes involving the interaction of qubits: the quantum carriers of information.
		In earlier papers, we have shown that quantum conditional entropies are negative for quantum entangled systems (1), which allows for a consistent interpretation of quantum information processes based on Einstein-Podolsky-Rosen (EPR) pairs (5).
		Quantum information theory is a statistical theory of information, and as such can be useful to examine non-equilibrium processes in quantum statistical mechanics.
	www.krl.caltech.edu /~adami/quantum.html (548 words)

	QiSci
		While existing purification protocols have been able to numerically demonstrate their performance, we present a purification protocol that is easily analysed, and prove it to be optimal in the presence of local noise.
		Quantum computers can solve certain problems substantially faster than classical computers, for example they can factor numbers in polynomial time whereas the best known classical algorithm runs in (almost) exponential time.
		Surprisingly, a (tight) lower bound for quantum search was shown 2 years before the discovery of the algorithm in a very influential paper by Bennett, Bernstein, Brassard, and Vazirani.
	www.qinfo.org (1394 words)

	QubitNews: Quantum Computers Quantum Information (Site not responding. Last check: 2007-10-14)
		Quantum theory is little understood outside the scientific community, but it offers huge potential for industry and society.
		However, despite recent advances in nanoscale engineering, developing quantum devices robust enough to be mass-produced outside the lab remains a scientific and technological challenge.
		Perhaps the main obstacle on the road to implementing a quantum computer is decoherence -- or the irrecoverable loss of quantum information to the environment.
	quantum.fis.ucm.es (856 words)

	Teleportation
		But now it is known that, through the phenomenon of quantum teleportation, they can deliver exactly that part of the information in an object which is too delicate to be scanned out and delivered by conventional methods.
		The scanned information is sent to the receiving station, where it is imprinted on some raw material (eg paper) to produce an approximate copy of the original.
		The scanned information is sent to the receiving station, where it is used to select one of several treatments to be applied to object C, thereby putting C into an exact replica of the former state of A.
	www.research.ibm.com /quantuminfo/teleportation (1034 words)

	Quantum Information Networks
		The new NIST architecture for quantum computing relies on several levels of error checking to ensure the accuracy of quantum bits (qubits).
		Richard Kuhn, A Hybrid Authentication Protocol Using Quantum Entanglement and Symmetric Cryptography, quant-ph/0301150, January 27, 2003.
		C program for generating a quantum circuit to add two binary numbers of any width.
	math.nist.gov /quantum (1460 words)

	Quantum Information Processing Jobs
		Calgary's Institute for Quantum Information Science (IQIS) is a multidisciplinary research institute presently involving the Departments of Computer Science, Physics & Astronomy, and Mathematics & Statistics, with the dual objectives of producing revolutionary advances in information and communication science and technology as well as to advance the understanding of quantum science through quantum information research.
		Members of IQIS conduct leading research in quantum algorithms and complexity and in atomic and photonic implementations of quantum information tasks and protocols, and soon a major effort will commence in the area of practical quantum cryptography.
		The Centre for Quantum Computation at the University of Cambridge expects to have a postdoctoral position in the area of quantum information theory and quantum computation.
	www-rcf.usc.edu /~tbrun/QIPJobs (3721 words)

	Quantum company information
		Support Notice: Quantum hard disk drive support is now supported by Maxtor.
		Founded in 1980 Quantum is a manufacturer of autoloaders, tape drive, and other data solutions.
		After 21 years of selling hard drives, Quantum on Friday formally left the business to turn its full attention to higher-level storage products and services.
	www.computerhope.com /comp/quantum.htm (62 words)

	John Preskill
		Broadly speaking, quantum information science addresses how the principles of quantum physics can be harnessed to improve the acquisition, transmission, and processing of information.
		A quantum computer would be a new type of machine that, by exploiting the unusual quantum properties of information, could perform certain types of calculations far more efficiently than any foreseeable classical computer.
		With some colleagues, I prepared a report on quantum information science for the National Science Foundation.
	theory.caltech.edu /people/preskill (519 words)

	Qubib (quantum bibliography) (Site not responding. Last check: 2007-10-14)
		Qubib is a bibliography database for the field of quantum information.
		Arvind, Dorai, K., and Kumar, A. Quantum entanglement in the NMR implementation of the deutsch-jozsa algorithm, 1999.
		Brukner, v., and Zeilinger, A. Conceptual inadequacy of the shannon information in quantum measurements.
	www.iqc.ca /~hollivie/qubib.html (7666 words)

	INI Programme QIS
		Quantum information science is a new field of science and technology.
		Deep links between the previously unrelated disciplines of quantum physics and computer science/information theory have been forged.
		Quantum information science is one of the most dynamic areas in the physical sciences and in information/computation theory, and new ideas and phenomena are appearing at a remarkable rate.
	www.newton.cam.ac.uk /programmes/QIS (205 words)

	C191 Quantum information (Site not responding. Last check: 2007-10-14)
		Contains some practical information about the sections, and then some discussion questions to get you started thinking about some basic questions in quantum mechanics and quantum information.
		Discussion questions about the role that unitary operators play in quantum mechanics, and why it is important that they be unitary.
		Questions that explore what happens to the state of a quantum system when you rotate it, how the operators that effect the rotation are tied to angular momentum, with the goal of trying to understand what intrinsic spin is.
	www-inst.eecs.berkeley.edu /~cs191/fa05 (2253 words)

	Quantum Information Systems Inc.
		Quantum Information Systems Inc. is an Information Systems consulting firm specializing in Project Staffing, Software Development, Project Management and Network Integration.
		We are located in the Washington DC Metro area, and have been in business since 1998.
		At Quantum Information Systems we take pride in the quality of our work.
	www.quantumtechee.com (143 words)

	Quantum Information Leeds (Site not responding. Last check: 2007-10-14)
		The Leeds Quantum Information Group (School of Physics and Astronomy, University of Leeds) conducts theoretical and experimental research into various aspects of quantum information processing, and into the implications of the quantum theory of computation for physics itself.
		The discovery that quantum physics allows fundamentally new modes of information processing has required the existing theories of computation, information and cryptography to be superseded by their quantum generalisations.
		New opening for experimental quantum information group at Leeds.
	quantum.leeds.ac.uk (193 words)

	The Andrew Steane and Derek Stacey Group homepage (Site not responding. Last check: 2007-10-14)
		On the theoretical side, this means quantum information theory, especially quantum computation.
		We are also developing experiments which will permit us to explore the physics of quantum information, testing basic ideas such as quantum error correction (see right).
		Our particular contribution has been to discover quantum error correction and to develop the most efficient fault-tolerant quantum computing methods.
	www.qubit.org /research/IonTrap (319 words)

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	www.vjquantuminfo.org (489 words)

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