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Topic: Quantum correlations

	Stanford Encyclopedia article
		Quantum field theory (see the forthcoming entry on quantum field theory) yields infinitely many representations of the commutation relations, which are inequivalent to the Schrödinger representation of standard quantum mechanics.
		According to Umezawa, coherent neuronal assemblies correlated to such memory states are regarded as vacuum states; their activation leads to excited states with a finite lifetime and enables a conscious recollection of the content encoded in the vacuum (ground) state.
		Inspired by the entanglement-induced nonlocal correlations of quantum physics, mind-matter entanglement is conceived as the hypothetical origin of mind-matter correlations.
	www.quantumconsciousness.org /StanfordEncyclopediaarticle.htm (8846 words)

	Relational Quantum Mechanics (Stanford Encyclopedia of Philosophy)
		The difficulty in the interpretation of quantum mechanics derives from the fact that the theory was first constructed for describing microscopic systems (atoms, electrons, photons) and the way these interact with macroscopic apparatuses built to measure their properties.
		Quantum events only happen in interactions between systems, and the fact that a quantum event has happened is only true with respect to the systems involved in the interaction.
		The conceptual relevance of correlations in quantum mechanics, — a central aspect of relational quantum mechanics — is emphasized by David Mermin, who analyses the statistical features of correlation (Mermin 1998), and arrives at views close to the relational ones.
	plato.stanford.edu /entries/qm-relational (5154 words)

	TAU Quantum Group - Topological Effects in Quantum Mechanics (Site not responding. Last check: 2007-10-20)
		Actually, the passive nonlocality of quantum correlations is distinct from the active nonlocality of the AB effect (action at a distance); Aharonov, Pendleton and Petersen [6] have shown how the AB effect implies nonlocal quantum equations of motion.
		Quantum topological and geometrical phases are ubiquitous in modern physics---in cosmology, particle physics, modern string theory, condensed matter, chemical and molecular physics, laser dynamics, and classical dynamical systems.
		Topological quantum phases are crucial in explaining superconductivity, the quantum Hall effect, the Josephson junction, flux quantization and many effects in the new field of mesoscopic physics, where tiny electronic circuits exhibit quantum behavior.
	www.tau.ac.il /~quantum/publicat/topo-effects.html (1118 words)

	quantum computing
		The TC model is known to exhibit important nonlinear quantum effects including a quantum phase transition\cite{Reiger} in which the (zero temperature) ground state undergoes a morphological change as a parameter is varied and averages of intensive quantities undergo a bifurcation.
		Quantum phase transitions occur at zero temperature and are driven by quantum fluctuations.
		For example in photoluminescence spectroscopy of quantum dots an optical signal is produced that is the incoherent superposition of luminescence from very many dots all with slightly varying physical characteristics (this leads to a substantial broadening of the PL spectrum).
	www.physics.uq.edu.au /people/milburn/quantum_computing.htm (1515 words)

	20th WCP: Quantum Holism as Consequence of the Relativistic Approach to the Problem of Quantum Theory Interpretation
		Therefore, we have to describe quantum systems in terms of potentialities and probabilities: since quantum systems cannot be analyzed completely into sets of elements, we can speak only of the potentialities of isolating elements and sets within their structure.
		The ontological basis for such a probability description of quantum systems and of primary importance of the probabilities themselves is the finite indivisibility of the system into elements or sets and the non-universal nature of the concept of set in the description of the world.
		This quantum correlation of the states of particles (demonstrated in the EPR experiment) is a trivial consequence of the implicative-logical organization of the probability structure of the initial state of the common system, a structure which follows from its quantum property of wholeness and its finite indivisibility into sets of elements.
	www.bu.edu /wcp/Papers/Scie/ScieTsek.htm (2390 words)

	oe magazine - Light Entanglements (Site not responding. Last check: 2007-10-20)
		Quantum information science (QIS) is creating a revolution in the way we think about information processing, communication, and computation, even as optics provides some of the most important technologies for testing proposals and demonstrating proofs of principle.
		Quantum dots emitting at 480 and 500 nm, for example, differ by only about 50 cadmium and selenium atoms, so reproducible synthetic methods require control down to the level of tens of atoms as the crystals are grown.
		Quantum dots, however, can easily be excited by a single source at any wavelength up to the blue edge of the emission and emit in narrow symmetric bands without excessive overlap.
	oemagazine.com /fromTheMagazine/aug04/quantum.html (2767 words)

	Quantum cryptography - Wikipedia, the free encyclopedia
		The effect arises because in quantum theory, certain pairs of physical properties are complementary in the sense that measuring one property necessarily disturbs the other.
		Quantum cryptography is still vulnerable to a type of MITM where the interceptor (Eve) establishes herself as "Alice" to Bob, and as "Bob" to Alice.
		Quantum cryptography was proposed first by Stephen Wiesner, then at Columbia University in New York, who, in the early 1970s, introduced the concept of quantum conjugate coding.
	en.wikipedia.org /wiki/Quantum_cryptography (2149 words)

	Quantum solitons (February 1999) - Physics World - PhysicsWeb
		Quantum noise is a consequence of the uncertainty principle, and arises because there is a quantum mechanical "incompatibility" between the generation and the detection processes for light pulses.
		One problem is that quantum fluctuations in the amplifiers lead to random jumps in the central wavelength of the individual solitons, and this results in a random variation of the speed of individual solitons in the fibre.
		Quantum information is an emerging field of physics that takes advantage of phenomena that are particular to quantum mechanics - such as uncertainty, superposition and entanglement - to code, transmit or process information (see Physics World March 1998).
	physicsweb.org /articles/world/12/2/8/1 (3168 words)

	Quantum Information Group
		Pure quantum correlations is measured by the entanglement of particles.
		In quantum computers these data are encoded in quantum states like the spin state of an electron or the polarization state of a photon.
		However with quantum computers and quantum algorithms these cryptosystems are no longer safe since we can factor a very large number (having for example 600 digits) in a reasonable time and break the code while with classical computers the same task may take a length of time comparable to the age of the universe.
	mehr.sharif.edu /~qc/fields.htm (829 words)

	Mind-Quantum role? (Site not responding. Last check: 2007-10-20)
		Another proposal by Marshall (1989) is that the mental and bodily realms derive directly from a quantum realm, as separate appearances of an underlying structure given by quantum mechanics.
		This therefore requires not only that the brain amplifies quantum indeterminism, but also that long-range and long-time correlations of quantum phases are set up in the brain, by means for example of a structure proposed by Fröhlich.
		In the language of physics, Marshall requires that non-local correlations (of the kind described by Bell's Inequalities) are set up between parts of the brain that are very far apart on the atomic scale, and hence that the brain exhibits some of the characteristics of `quantum computers' as described by Deutsch (1985).
	www.newdualism.org /minds-qm.htm (1359 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)

	Publications (Site not responding. Last check: 2007-10-20)
		In the realm of the nonlocal quantum phenomena,
		The GAP-Optics experiments studying the quantum correlations with moving observers was a first for a new kind of experiment to test quantum non-locality.
		Contrary to standard quantum mechanics, it predicts a disappearance of the correlations in a Bell-type experiment when both analyzers are in relative motion such that each one, in its own inertial reference frame, is first to select the output of the photons.
	www.quantumphil.org /publications.htm (1316 words)

	Rules for a Complex Quantum World -- [ INFORMATION TECHNOLOGY ]: Scientific American (Site not responding. Last check: 2007-10-20)
		The criteria of success become more subtle than in the classical case, because to extract the result of a quantum information-processing task we must observe, or measure, the system--which almost inevitably changes it, destroying the special superposition states that are unique to quantum physics.
		Quantum information science begins by generalizing the fundamental resource of classical information--bits--to quantum bits, or qubits.
		One line of reasoning suggests the amount is infinite: To specify a quantum state we need to specify the latitude and longitude of the corresponding point on the sphere, and in principle each may be given to arbitrary precision.
	www.sciam.com /article.cfm?articleID=0005C8BF-1B88-1D9B-815A809EC5880000&pageNumber=3&catID=2 (776 words)

	QUANTUM PHYSICS: ON CORRELATIONS AND ENTANGLEMENT
		Real electrons, on the other hand, behave quantum mechanically; their spin measurements can be correlated in the vertical direction at the same time as in the horizontal direction (and all other directions!).
		Quantum mechanical entanglement is a phenomenon that has caught the imagination of the public as one of the more bizarre consequences of fundamental physical theory.
		For many quantum mechanical physical systems, the fixation of boundary conditions is a theoretical and fundamental consequence of some interaction of the physical system with something outside that system, e.g., an interaction with the measuring device of an observer.
	scienceweek.com /2006/sw060407-1.htm (1466 words)

	Another new twist on the Hanbury Brown-Twiss effect (January 2007) - News - PhysicsWeb
		Quantum mechanics aside, one might expect the atoms to arrive at the detector randomly.
		Westbrook says similar HBT methods could be used to accurately detect quantum correlations in systems where the behaviour is strongly governed by it, such as those displaying the fractional quantum Hall effect.
		"Being able to observe quantum correlations in such systems would be a very important step forward," he said.
	www.physicsweb.org /archive/news/11/1/21/1?rss=2.0 (434 words)

	Quantum Nocality - Cramer
		Quantum mechanics (QM) was invented in the late 1920's when an embarrassing body of new experimental facts from the microscopic world couldn't be explained by the accepted physics of the period.
		At minimum it should be clear that the transactional interpretation is not a clumsy appendage gratuitously grafted onto the formalism of quantum mechanics but rather a description which, after one learns the key to the language, is found to be graphically represented within the quantum wave mechanics formalism itself.
		However, this prohibition is broken if quantum mechanics is allowed to be slightly "non-linear", a technical term meaning that when quantum waves are superimposed they may generate a small cross-term not present in the standard formalism.
	www.npl.washington.edu /npl/int_rep/qm_nl.html (2861 words)

	Quantum Approaches to Consciousness (Stanford Encyclopedia of Philosophy)
		Quantum field theory (see the entry on quantum field theory) yields infinitely many representations of the commutation relations, which are inequivalent to the Schrödinger representation of standard quantum mechanics.
		However, ways in which these quantum processes might be relevant for mental activity, and in which their interactions with mental states are conceived, remain unclarified to the present day.
		Shimony, A. “Role of the observer in quantum theory”.
	plato.stanford.edu /entries/qt-consciousness (9302 words)

	Energy Citations Database (ECD) - Energy and Energy-Related Bibliographic Citations
		Atoms as nonlinear mixers for detection of quantum correlations at ultrahigh frequencies
		Measurements of quantum correlations are reported for a frequency difference of 25 THz between the signal and idler output fields generated by a subthreshold nondegenerate optical parametric oscillator.
		The observed phase-sensitive modulation is proportional to the correlation function{l_angle}{cflx E}{sub s}{cflx E}{sub i}{r_angle} for the quantized signal and idler fields.{copyright}{ital 1997}{ital The American Physical Society}
	www.osti.gov /energycitations/product.biblio.jsp?osti_id=467363&query_id=0 (232 words)

	SAP: Mesoscopic Correlations...Quantum Dot Systems
		The realization of the quantum computer relies on the successful measurement and control of the exchange energy (energy difference between two electron singlet and triplet states) in the double quantum dot system, which so far has been eluding the direct observation, though recent indirect estimates gave a value of about 20 meV [3].
		Therefore, the development of accurate theoretical and computational methods capable of unraveling the many-electron problem by fully accounting for the correlation effects among electrons confined in the quantum-dot device is of the great fundamental and practical importance.
		Note that by using the same grid and the finite elements method, it may be easier to couple the exact diagonalization method with the already existing multi-scale device simulation code (which now relies on the density functional theory in the description of the QD electrons).
	www.ncsa.uiuc.edu /UserInfo/SAP/project8.html (1236 words)

	Chapline
		It is proposed that the event horizon of a fl hole is a quantum phase transition of the vacuum of space-time analogous to the liquid-vapor critical point of a bose fluid.
		One such possible effect is that the event horizon of a fl hole differs from the one predicted by classical general relativity whereby space-time vacuum rearranges itself in such a manner that time is universally defined...
		The Cerf-Adami "quantum information theory" on "curved spacetime" may be just another way of describing the "critical surface" at which "the vacuum of space-time reorganizes itself so as to keep global time defined", according to Chapline et al.
	www.valdostamuseum.com /hamsmith/GChapline.html (1156 words)

	Co to Cy
		The definition is based on the valence-bond formulation of the quantum mechanical idea of the wavefunction of a molecule as composed of a linear combination of wavefunctions, each representative of a formula containing bonds that are only single, double or triple with a particular pairing of electron spins.
		The use of empirical correlations relating one body of experimental data to another, with the objective of finding quantitative estimates of the factors underlying the phenomena involved.
		Correlation analysis in organic chemistry often uses linear free-energy relations for rates or equilibria of reactions, but the term also embraces similar analysis of physical (most commonly spectroscopic) properties and of biological activity.
	www.chem.qmw.ac.uk /iupac/gtpoc/CoCy.html (2463 words)

	Thwarting Post-Quantum Spies
		Transmitting a binary number using the weirdness of quantum mechanics to detect eavesdroppers would work even if current quantum theory turns out to be incomplete, according to a new proof, as long as signals still can't be sent faster than light.
		A new quantum mechanical recipe for encoding messages remains uncrackable even if the rules of quantum mechanics aren't quite right--so long as it's not possible to send messages faster than light.
		Quantum mechanics would prevent her from reading the key without detection, but Kent and colleagues suppose that she can manipulate particles in new ways using her understanding of a post-quantum theory.
	focus.aps.org /story/v15/st22 (759 words)

	The Function of Information In Quantum-Genetic Correlations
		This concept is related to the idea of “quantum matter”, first proposed by H. Stapp [1], and to the corresponding “quantum phase states of Stapp’s “quantum matter”, as proposed by the writer [2].
		Perhaps in the observed genetic quantum correlations, information density can be viewed as an additive function and might be cumulative over time, resulting in the kind of memory function that is already known to be inherent in the media.
		Quantum results are inherently incomplete, because it appears that we can never possibly have access to all the information which has been involved internal to the quantum “fl box” to produce the results which come out of the quantum fl box.
	www.rialian.com /rnboyd/information-in-quantumgenetic-correlations.htm (1020 words)

	Shimony's Passion
		Quantum mechanics permits nonlocality, both nonlocal correlations and nonlocal equations of motion, while respecting relativistic causality.
		For quantum correlations, however, the CHSH sum of correlations is bounded [15] in absolute value by 2 ^1/ 2.
		(Quantum mechanics, of course, does not.) Here, our concern is not with hidden-variable theories or with a mechanism for jamming; rather, we ask whether such a nonlocal equation of motion (or one, say, allowing the third experimenter nonlocally to create, rather than jam, nonlocal correlations) could respect causality.
	www.qedcorp.com /pcr/pcr/passion.html (5482 words)

	IST DM Quantum Computation and Information Seminar
		This statement, which has been described as "the most profound discovery of science," is based on the fact that some predictions of quantum mechanics violate Bell's inequalities, derived from some assumptions of classical physics.
		We use these results to quantify the success of some approximate characterizations of the set of quantum correlations using linear and quadratic inequalities.
		The quantum correlations appearing in the CHSH-Bell inequality can give values between the classical bound and Tsirelson's bound.
	sem.math.ist.utl.pt /qci/abstract.xml?who=Ad%26aacute%3Bn%20Cabello&when=Fri%2003%20Dec%202004%2003%3A00%3A00%20PM%20WET (233 words)

	INI : Abstracts : QIS_FOCUS : Quantum Correlations in Quantum Cryptography (Site not responding. Last check: 2007-10-20)
		In basic quantum communication protocols one party creates quantum states and uses a quantum channel to transmit it to another party that performs immediately some measurement on it.
		In the specific example of quantum key distribution one uses the correlations to distill a secret key in (classical) public discussion protocols e.g.
		We give a necessary condition for the success of any public discussion protocol: the observed correlations should allow to prove the presence of an internal, virtual state of entanglement in the distribution.
	www.newton.cam.ac.uk /programmes/QIS/Abstract3/lutkenhaus.html (173 words)

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