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	Quantum phase transition - Wikipedia, the free encyclopedia
		It signals a reorganization of the particles; A canonical example is the freezing transition of water describing the transition between liquid and ice.
		The classical phase transitions are driven by a competition between the energy of a system and the entropy of its thermal fluctuations.
		A canonical quantum phase transition is the well-studied superconductor/insulator transition in disordered thin films which separates two quantum phases having different symmetries.
	en.wikipedia.org /wiki/Quantum_phase_transition (267 words)

	Quantum phase transitions (Site not responding. Last check: 2007-11-06)
		Quantum Phase Transitions Introduction to the subject and outline of a book by Subir Sachdev.
		Subir Sachdev Theoretical research on quantum phase transitions and their application to correlated electron materials like the high temperature superconductors and other complex oxides.
		Opole PL: University of, Division of Crystallography Studies of structures and phase transitions.
	www.serebella.com /encyclopedia/article-Quantum_phase_transitions.html (532 words)

	Yale Scientific Magzine
		To transit from one phase to another, the amount of heat that enters or leaves the matter must reach a critical point, resulting in a transition that occurs at a specific temperature under a given pressure.
		It is analogous to the superfluid-insulator transition in that it involves the interplay between two observables, namely, the arrangement of the spins and quantum fluctuations, dictated once again by the uncertainty principle.
		In the antiferromagnetic phase, the checkerboard arrangement of the spins is so precise that, according to the principle, some other factor has to grow “fuzzy.” This factor is in the form of quantum fluctuations which alter the magnetic spin.
	research.yale.edu /ysm/article.jsp?articleID=2 (2013 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)

	Learn more about Quantum phase transitions in the online encyclopedia. (Site not responding. Last check: 2007-11-06)
		Quantum phase transitions are changes in matter that occur because of quantum behaviour.
		As opposed to classical behaviour (see classical physics and phase changes).
		For certain types of material Quantum Phase transitions are important, for example the Bose-Einstein Condensate.
	www.onlineencyclopedia.org /q/qu/quantum_phase_transitions.html (149 words)

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		Classical phase transitions occur at a finite temperature, A material that is tuned close to a classical phase transition senses the imminent change of state as the order parameter develops thermal fluctuations over larger and larger regions of the sample: such a state is known as a "critical state".
		The development of a unified understanding of thermal phase transitions and “classical criticality” was a triumph of the 20th century.
		We are still far from a complete understanding of quantum phase transitions, but already, many suspect that the ultimate solution to this problem may be needed to understand and ultimately control phenomena such as high temperature superconductivity will depend on the development of a new theory of quantum phase transitions.
	www.physics.rutgers.edu /qcritical/frontier3.htm (762 words)

	Professor Broholm - Research (Site not responding. Last check: 2007-11-06)
		QUANTUM DISORDERED PHASES IN ONE DIMENSION: The prime example of a T=0 quantum disordered phase is the antiferromagnetic integer spin chain alluded to earlier.
		We will induce the transition by the application of pressure or large magnetic fields to well defined model systems, and study the ordered phase and the critical properties of the phase transition using magnetic neutron scattering.
		It may also be possible to explore the critical properties of the phase transition from disorder back to order at zero temperature by the application of pressure.
	www.pha.jhu.edu /~broholm/homepage/research.htm (1097 words)

	Quantum Phase Transitions
		This is a transition between ground states occurring at zero temperature and controlled by a different parameter, such as pressure, doping or magnetic field.
		Some materials are located close to a QPT [3], meaning that the energy scales relevant for physical phenomena are far smaller than the scales intrinsic to the system, and in these cases it is possible that (physical or chemical) pressure could indeed drive it through the transition.
		For field-induced quantum criticality, there is only one low-lying mode, which at the QPT becomes the sole massless phase mode (Goldstone mode) of the field-ordered magnetic regime, whose dispersion at the band minimum retains its quadratic form at the critical field, with a linear component developing above this field [5-7].
	www.physik.uni-augsburg.de /theo3/bnormand/qpt.shtml (900 words)

	Harvard Gazette: Probing boundary between worlds
		Though "quantum phase transitions" may be an off-putting term, Sachdev uses the familiar event of ice melting to water to explain what is going on.
		Similarly, with quantum phase transitions, adding some external perturbation to a superconductor - such as applying pressure or putting it in a magnetic field - can cause its properties to change, sometimes dramatically.
		In a quantum phase transition, the role of heat is played by the fluctuations demanded by Heisenberg's uncertainty principle.
	www.news.harvard.edu /gazette/2005/10.06/03-sachdev.html (738 words)

	Quantum phase transitions (April 1999) - Physics World - PhysicsWeb
		Phase transitions are normally associated with changes of temperature but a new type of transition - caused by quantum fluctuations near absolute zero - is possible, and can tell us more about the properties of a wide range of systems in condensed-matter physics.
		The universe itself is thought to have passed through several phase transitions as the high-temperature plasma formed by the big bang cooled to form the world as we know it today.
		In particular, the quantum system is described by a complex-valued wavefunction, and the dynamics of its phase near the quantum critical point requires novel theories that have no analogue in the traditional framework of phase transitions.
	physicsweb.org /articles/world/12/4/9 (442 words)

	Quantum phase transitions at opensource encyclopedia (Site not responding. Last check: 2007-11-06)
		Quantum Phase Transitions is the first book to describe in detail the fundamental changes that can...
		The main concepts relating to quantum phase transitions are explained, using the paramagnet-to...
		In quantum phase transitions, which occur in rare...
	www.springknow.com /Quantum_phase_transitions.html (228 words)

	Under construction... (Site not responding. Last check: 2007-11-06)
		A phase transition is a discontinuity in the properties of a thermodynamic system reflecting a change in the basic organization of the particles in the system.
		Simple examples of classical phase transitions are the boiling of a liquid into a gas, or the development of a spontaneous magnetic moment in a ferromagnet.
		These quantum phase transitions can in many cases be understood by adapting the beautiful theory of classical phase transitions developed by Kenneth Wilson and many others in the 1970s.
	sda.berkeley.edu:7502 /~jemoore/qpt (194 words)

	Pigeonholing quantum phase transitions
		Melting ice and boiling water are examples of phase transitions that arise from changes in temperature, which can easily be described using classical physics.
		As the metals change quantum phases, they pass through a stage known as the "critical point" in which all electrons throughout the material respond collectively and can no longer be regarded as individual particles.
		One of these is the locally-critical quantum phase transition, a new class of quantum phase transition first proposed by Si and colleagues in an article in Nature two years ago.
	www.eurekalert.org /pub_releases/2003-08/ru-pqp080503.php (777 words)

	COOPERATIVE PHENOMENA IN CONDENSED MATTER (Site not responding. Last check: 2007-11-06)
		The effect of the quantum correlations on the phase transition properties has been considered with the help of basic models of statistical physics.
		A systematic treatment of the magnetic fluctuations effect on the properties of the normal-to-superconducting phase transition in a zero external magnetic field is given within the self-consistent approximation.
		The phase of coexistence of superconductivity and ferromagnetism and the possible phase transitions of first and second order in spin-triplet ferromagnetic superconductors (UGe2, ZrZn2, URhGe) were investigated [7-9].
	www.issp.bas.bg /a-r_2003/coop_phenom.html (604 words)

	Quantum Phase Transitions - Cambridge University Press
		Quantum Phase Transitions is the first book to describe in detail the fundamental changes that can occur in the macroscopic nature of matter at zero temperature due to small variations in a given external parameter.
		Particular attention is paid to their non-zero temperature dynamic and transport properties in the vicinity of the quantum critical point.
		Several other quantum phase transitions of increasing complexity are then discussed and clarified.
	www.cambridge.org /uk/catalogue/catalogue.asp?isbn=0521004543 (333 words)

	Quantum phase transitions -- Facts, Info, and Encyclopedia article (Site not responding. Last check: 2007-11-06)
		Quantum phase transitions are changes in matter that occur because of ((physics) the smallest discrete quantity of some physical property that a system can possess (according to quantum theory)) quantum behaviour.
		Normally only relevant at temperatures close to ((cryogenics) the lowest temperature theoretically attainable (at which the kinetic energy of atoms and molecules is minimal); 0 Kelvin or -273.15 Centigrade or -459.67 Fahrenheit) absolute zero.
		For certain types of material Quantum Phase transitions are important, for example the (Click link for more info and facts about Bose-Einstein Condensate) Bose-Einstein Condensate.
	www.absoluteastronomy.com /encyclopedia/q/qu/quantum_phase_transitions.htm (138 words)

	OSU Physics: Colloquium Abstract (Site not responding. Last check: 2007-11-06)
		Standard classical phase transitions (which occur at finite temperatures) and standard quantum phase transitions (which occur at zero temperature) always involve a change in symmetry.
		However, topological quantum phase transitions do not involve a change in symmetry, but involve a change in the topology of the ground state (T = 0).
		The particular case of a d-wave superconductor with varying charge carrier concentration will be discussed as an example of a topological quantum phase transition.
	www.physics.ohio-state.edu /news/sademelo.php (118 words)

	Pitkanen II.
		Magnetic quantum phase transitions allow place coding by a varying cyclotron frequency (flux tube thickness) and the models for sensory representations, long term memory, frequency imprinting and electromagnetic aspects of DNA rely on the hierarchy of magnetic laser mirrors consisting of MEs parallel to magnetic flux tubes.
		Quantum criticality fixes the value of the Kähler coupling strength \alpha_K as a parameter analogous to critical temperature and makes TGD a unique theory (as a matter fact, entire hierarchy of values of \alpha_K corresponding to p-adic length scale hierarchy appears).
		These quantum phase transitions are crucial in the model of sensory representations based on the notion of magnetic sensory canvas: these representations could occur in several length scales.
	www.emergentmind.org /pitkanen_III.htm (11022 words)

	Phase Transitions in Quantum Systems at Carolina
		Both experimental and theoretical studies of phase transitions in quantum systems are carried out in our department.
		The work of Professors Washburn and Kveshchenko is particularly concerned with the breakdown of Landau’s Fermi liquid approximation that allows one to treat the entire effect of the carrier interactions with the lattice and other carriers as an effective mass of an essentially free quasiparticle.
		Professor Hernandez’s theoretical research is focused on the liquid-vapor phase transition in systems composed of atoms whose valence electrons are “weakly” bound, such as the alkali fluids, in which the dilute vapor is insulating while the dense liquid is metallic.
	www.physics.unc.edu /research/nano/phase_trans.php (281 words)

	Quantum Phase Transitions (Site not responding. Last check: 2007-11-06)
		Wang is developing new field theories and numerical approaches to understand the fundamental new physics associated with the transitions between the adjacent quantum Hall plateau phases.
		The new theoretical framework is used to study the transport properties in multi-layer quantum wells, semiconductor superlattices, as well as various aspects of the quantum Hall effect between two and three dimensions.
		Also underway is the study of the transport properties in bulk-homogeneous semiconductors in which the effects of many-body correlations are important for observing the quantum Hall effect.
	physics.bu.edu /quantum_phase.html (190 words)

	Quantum criticality in your car bumper (January 2003) - Physics World - PhysicsWeb
		Classical examples of quantum phase transitions, such as superconductivity and magnetism occur at finite temperatures, but when the phase-transition temperature is suppressed to near absolute zero, quantum effects become important.
		A material that is close to a classical phase transition senses thermal fluctuations that develop in the order parameter over successively larger regions.
		Once thought to be of purely academic interest, the phenomenon of quantum phase transitions has emerged as a major challenge to our understanding of condensed matter.
	physicsweb.org /article/world/16/1/5/1 (308 words)

	Dietrich Belitz (Site not responding. Last check: 2007-11-06)
		Quantum phase transitions take place at zero temperature as some non-thermal control parameter is varied.
		Prominent examples are the ferromagnetic transition of itinerant electrons at low temperature as a function of pressure, or the metal-insulator transition in doped semiconductors as a function of the dopant concentration.
		While the concepts developed for thermal phase transitions, such as scaling and universality, and the general apparatus of the renormalization group, still apply, the detailed behavior in the vicinity of quantum phase transitions has proven to be rather complex and hard to understand.
	physics.uoregon.edu /~belitz/db_virtual/db.html (263 words)

	Thomas Vojta
		Mark Dickison and Thomas Vojta, Monte Carlo simulations of the smeared phase transition in a contact process with extended defects, J. Phys.
		Thomas Vojta, Broadening of a nonequilibrium phase transition by extended structural defects, Phys.
		Rastko Sknepnek, Thomas Vojta and Raj Narayanan, Order-parameter symmetry and mode-coupling effects at dirty superconducting quantum phase transitions, Phys.
	web.umr.edu /~vojtat/research/research.html (336 words)

	Annotated Physics Encyclopædia
		Quantum phase transitions (cond-mat/9811058), 27pp - from classical critical phenomena to quantum phase transitions.
		Quantum phase transitions in 2D quantum liquids (cond-mat/9811393), 78pp., by A. Schakel - pedagogical introduction to the theory of continuous quantum phase transitions with multiple exaples.
		Properties of phase transitions of higher order (cond-mat/9611047), 13pp - phase transitions of III and IV order are briefly discussed.
	web.mit.edu /afs/athena.mit.edu/user/r/e/redingtn/www/netadv/phase.html (226 words)

	AIP Queensland Branch
		Quantum phase transitions refer to a morphological change in the nature of a ground state as some external parameter is varied.
		We show how quantum entanglement in the ground state of interacting quantum systems can arise from dynamical instabilities in the phase space of the corresponding classical system.
		In the case of many body systems, the change in ground state entanglement at dynamical instabilities is related to the phenomenon of quantum phase transitions.
	www.physics.uq.edu.au /AIPqld/activities_seminars.html (702 words)

	Zheludev_Abstract (Site not responding. Last check: 2007-11-06)
		The two distinct spin-liquid phases differ in their "hidden" symmetries associated with antiferromagnetic string order that is present in the Haldane state but absent in the dimerized one.
		Applying an external magnetic field to either type of spin liquid leads to a quantum phase transition driven by a "fully legitimate" 1D Bose condensation of magnons.
		The high-field state is a "quantum spin solid" where long-range order coexists with exotic excitations that have no analogues in conventional spin wave theory.
	panda.unm.edu /CAS/Zheludev_Abstract.html (330 words)

	Condensed Matter Seminars (Site not responding. Last check: 2007-11-06)
		Quantum phase transitions, i.e., phase transitions taking place at zero temperature, have attracted the interest of both theorists
		The focus of the second part is on competing orders and quantum phase transitions in high-temperature superconductors.
		The unusual properties of these materials and the possible connection to quantum criticality have been subject to an intense debate in recent years.
	www.phy.duke.edu /research/cmtheory/cmseminarspring03/Vojta.html (128 words)

	Quantum phase transitions in correlated metals (Site not responding. Last check: 2007-11-06)
		Research on strongly correlated metals has recently received a considerable impetus by the recognition that these materials are exemplary systems to study quantum phase transitions in 3D.
		Because of strong electron hybridisation phenomena, magnetic transition temperatures of correlated metals can relatively easily be tuned to a critical point at zero temperature by mechanical or chemical pressure.
		In the vicinity of the quantum critical point, the phase transition is driven by quantum fluctuations rather than by thermal fluctuations, which results in novel non-Fermi liquid behaviour, i.e.
	www.science.uva.nl /research/wzi/colloquium/oldabstracts/devisser.html (148 words)

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