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Hardy's Paradox
Hardy's paradox is a thought experiment in quantum mechanics devised by Lucien Hardy in 1992–1993 in which a particle and its antiparticle may interact without Annihilation, annihilating each other. Experiments. Also availablhere using the technique of weak measurement have studied an interaction of Photon polarization, polarized photons, and these have demonstrated that the phenomenon does occur. However, the consequence of these experiments is only that past events can be inferred after their occurrence as a probabilistic wave collapse. These weak measurements are considered to be an observation themselves, and therefore part of the causation of wave collapse, making the objective results only a probabilistic function rather than a fixed reality. However, a careful analysis of the experiment shows that Hardy's paradox only proves that a local hidden-variable theory can not exist, as there can not be a theory that assumes that the system meets the states of reality regardless of t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thought Experiment
A thought experiment is a hypothetical situation in which a hypothesis, theory, or principle is laid out for the purpose of thinking through its consequences. History The ancient Greek ''deiknymi'' (), or thought experiment, "was the most ancient pattern of mathematical proof", and existed before Euclidean mathematics, where the emphasis was on the conceptual, rather than on the experimental part of a thought-experiment. Johann Witt-Hansen established that Hans Christian Ørsted was the first to use the German term ' (lit. thought experiment) circa 1812. Ørsted was also the first to use the equivalent term ' in 1820. By 1883 Ernst Mach used the term ' in a different way, to denote exclusively the conduct of a experiment that would be subsequently performed as a by his students. Physical and mental experimentation could then be contrasted: Mach asked his students to provide him with explanations whenever the results from their subsequent, real, physical experiment differed ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interaction-free Measurement
In physics, interaction-free measurement is a type of measurement in quantum mechanics that detects the position, presence, or state of an object without an interaction occurring between it and the measuring device. Examples include the Renninger negative-result experiment In quantum mechanics, the Renninger negative-result experiment is a thought experiment that illustrates some of the difficulties of understanding the nature of wave function collapse and measurement in quantum mechanics. The statement is that a pa ..., the Elitzur–Vaidman bomb-testing problem, and certain double-cavity optical systems, such as Hardy's paradox. In Quantum Computation such measurements are referred to as Counterfactual Quantum Computation, an idea introduced by physicists Graeme Mitchinson and Richard Jozsa. Examples include Keith Bowden's Counterfactual Mirror ArrayBowden, Keith G, "Classical Computation can be Counterfactual", in Aspects I, Proc ANPA19, Cambridge 1997 (published May 1999), des ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Idealism
In philosophy, the term idealism identifies and describes metaphysical perspectives which assert that reality is indistinguishable and inseparable from perception and understanding; that reality is a mental construct closely connected to ideas. Idealist perspectives are in two categories: subjective idealism, which proposes that a material object exists only to the extent that a human being perceives the object; and objective idealism, which proposes the existence of an ''objective'' consciousness that exists prior to and independently of human consciousness, thus the existence of the object is independent of human perception. The philosopher George Berkeley said that the essence of an object is to be perceived. By contrast, Immanuel Kant said that idealism "does not concern the existence of things", but that "our modes of representation" of things such as ''space'' and ''time'' are not "determinations that belong to things in themselves", but are essential features of the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Measurement
In quantum physics, a measurement is the testing or manipulation of a physical system to yield a numerical result. The predictions that quantum physics makes are in general probabilistic. The mathematical tools for making predictions about what measurement outcomes may occur were developed during the 20th century and make use of linear algebra and functional analysis. Quantum physics has proven to be an empirical success and to have wide-ranging applicability. However, on a more philosophical level, debates continue about the meaning of the measurement concept. Mathematical formalism "Observables" as self-adjoint operators In quantum mechanics, each physical system is associated with a Hilbert space, each element of which represents a possible state of the physical system. The approach codified by John von Neumann represents a measurement upon a physical system by a self-adjoint operator on that Hilbert space termed an "observable". These observables play the role of measurab ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Wave Function Collapse
In quantum mechanics, wave function collapse occurs when a wave function—initially in a superposition of several eigenstates—reduces to a single eigenstate due to interaction with the external world. This interaction is called an ''observation'', and is the essence of a measurement in quantum mechanics, which connects the wave function with classical observables such as position and momentum. Collapse is one of the two processes by which quantum systems evolve in time; the other is the continuous evolution governed by the Schrödinger equation. : Collapse is a black box for a thermodynamically irreversible interaction with a classical environment. Calculations of quantum decoherence show that when a quantum system interacts with the environment, the superpositions ''apparently'' reduce to mixtures of classical alternatives. Significantly, the combined wave function of the system and environment continue to obey the Schrödinger equation throughout this ''apparent'' col ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uncertainty Principle
In quantum mechanics, the uncertainty principle (also known as Heisenberg's uncertainty principle) is any of a variety of mathematical inequalities asserting a fundamental limit to the accuracy with which the values for certain pairs of physical quantities of a particle, such as position, ''x'', and momentum, ''p'', can be predicted from initial conditions. Such variable pairs are known as complementary variables or canonically conjugate variables; and, depending on interpretation, the uncertainty principle limits to what extent such conjugate properties maintain their approximate meaning, as the mathematical framework of quantum physics does not support the notion of simultaneously well-defined conjugate properties expressed by a single value. The uncertainty principle implies that it is in general not possible to predict the value of a quantity with arbitrary certainty, even if all initial conditions are specified. Introduced first in 1927 by the German physicist Werner ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Half-wave Plate
A waveplate or retarder is an optical device that alters the polarization state of a light wave travelling through it. Two common types of waveplates are the ''half-wave plate'', which shifts the polarization direction of linearly polarized light, and the ''quarter-wave plate'', which converts linearly polarized light into circularly polarized light and vice versa. A quarter-wave plate can be used to produce elliptical polarization as well. Waveplates are constructed out of a birefringent material (such as quartz or mica, or even plastic), for which the index of refraction is different for light linearly polarized along one or the other of two certain perpendicular crystal axes. The behavior of a waveplate (that is, whether it is a half-wave plate, a quarter-wave plate, etc.) depends on the thickness of the crystal, the wavelength of light, and the variation of the index of refraction. By appropriate choice of the relationship between these parameters, it is possible to introduce ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Barium Borate
Barium borate is an inorganic compound, a borate of barium with a chemical formula BaB2O4 or Ba(BO2)2. It is available as a hydrate or dehydrated form, as white powder or colorless crystals. The crystals exist in the high-temperature α phase and low-temperature β phase, abbreviated as BBO; both phases are birefringent, and BBO is a common nonlinear optical material. Barium borate was discovered and developed by Chen Chuangtian and others of the Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences. Properties Barium borate exists in three major crystalline forms: alpha, beta, and gamma. The low-temperature beta phase converts into the alpha phase upon heating to 925 °C. β-Barium borate (BBO) differs from the α form by the positions of the barium ions within the crystal. Both phases are birefringent, however the α phase possesses centric symmetry and thus does not have the same nonlinear properties as the β phase. Alpha barium bo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jeff Lundeen
Jeff is a masculine name, often a short form (hypocorism) of the English given name Jefferson or Jeffrey, which comes from a medieval variant of Geoffrey. Music * DJ Jazzy Jeff, American DJ/turntablist record producer Jeffrey Allen Townes * Excision (musician), Canadian dubstep producer and DJ Jeff Abel * Jeff Abercrombie, bassist for American rock band Fuel * Jeff Allen, English session drummer * Jeff Baxter, American guitarist for rock bands Steely Dan and The Doobie Brothers * Jeff Beal (born 1963), American composer of music for various media * Jeff Beck, electric guitarist * Jeff Buckley, American singer-songwriter * Jeff Coffin, saxophonist, bandleader, composer and educator * Jeff Current, lead singer of American alternative rock band Against All Will * Jeff Fatt, Australian musician and actor, formerly with the children's band The Wiggles * Jeff Gillan, an American journalist * Jeff Graham, Canadian radio DJ * Jeff Hanneman (1964–2013), American guitarist, founding ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Yakir Aharonov
Yakir Aharonov ( he, יקיר אהרונוב; born August 28, 1932) is an Israeli physicist specializing in quantum physics. He has been a Professor of Theoretical Physics and the James J. Farley Professor of Natural Philosophy at Chapman University in California since 2008. He is also a distinguished professor in the Perimeter Institute and a professor emeritus at Tel Aviv University in Israel. He is president of the IYAR, The Israeli Institute for Advanced Research. Biography Yakir Aharonov was born in Haifa. He received his undergraduate education at the Technion – Israel Institute of Technology in Haifa, graduating with a BSc in 1956. He continued his graduate studies at the Technion and then moved to Bristol University, UK together with his doctoral advisor David Bohm, receiving a Ph.D. degree in 1960. Aharonov later taught at the Brandeis University from 1960–61 and the Yeshiva University from 1964–67, both in the United States. Academic career His research interest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Local Hidden Variables
In the interpretation of quantum mechanics, a local hidden-variable theory is a hidden-variable theory that satisfies the condition of being consistent with local realism. This includes all types of the theory that attempt to account for the probabilistic features of quantum mechanics by the mechanism of underlying inaccessible variables, with the additional requirement from local realism that distant events be independent, ruling out ''instantaneous'' (that is, faster-than-light) interactions between separate events. The mathematical implications of a local hidden-variable theory in regard to the phenomenon of quantum entanglement were explored by physicist John Stewart Bell, who in 1964 proved that broad classes of local hidden-variable theories cannot reproduce the correlations between measurement outcomes that quantum mechanics predicts. The most notable exception is superdeterminism. Superdeterministic hidden-variable theories can be local and yet be compatible with observati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
