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Counterfactual Quantum Computation
Counterfactual quantum computation is a method of inferring the result of a computation without actually running a quantum computer otherwise capable of actively performing that computation. Conceptual origin Physicists Graeme Mitchison and Richard Jozsa introduced the notion of counterfactual computing as an application of quantum computing, founded on the concepts of counterfactual definiteness, on a re-interpretation of the Elitzur–Vaidman bomb tester thought experiment, and making theoretical use of the phenomenon of interaction-free measurement. As an example of this idea, in 1997, after seeing a talk on counterfactual computation by Jozsa at the Isaac Newton Institute. Keith Bowden based in the Theoretical Physics Research Unit at Birkbeck College, University of London, published a paper Bowden, Keith G, "Classical Computation can be Counterfactual", in Aspects I, Proc ANPA19, Cambridge 1997 (published May 1999), describing a digital computer that could be counterfactua ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Computing
Quantum computing is a type of computation whose operations can harness the phenomena of quantum mechanics, such as superposition, interference, and entanglement. Devices that perform quantum computations are known as quantum computers. Though current quantum computers may be too small to outperform usual (classical) computers for practical applications, larger realizations are believed to be capable of solving certain computational problems, such as integer factorization (which underlies RSA encryption), substantially faster than classical computers. The study of quantum computing is a subfield of quantum information science. There are several models of quantum computation with the most widely used being quantum circuits. Other models include the quantum Turing machine, quantum annealing, and adiabatic quantum computation. Most models are based on the quantum bit, or "qubit", which is somewhat analogous to the bit in classical computation. A qubit can be in a 1 or 0 quantum s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Graeme Mitchison
Graham and Graeme may refer to: People * Graham (given name), an English-language given name * Graham (surname), an English-language surname * Graeme (surname), an English-language surname * Graham (musician) (born 1979), Burmese singer * Clan Graham, a Scottish clan * Graham baronets Fictional characters * Graham Aker, in the anime ''Gundam 00'' * Project Graham, what a human would look like to survive a car crash Places Canada * Graham, Sudbury District, Ontario * Graham Island, part of the Charlotte Island group in British Columbia * Graham Island (Nunavut), Arctic island in Nunavut United States * Graham, Alabama * Graham, Arizona * Graham, Florida * Graham, Georgia * Graham, Daviess County, Indiana * Graham, Fountain County, Indiana * Graham, Kentucky * Graham, Missouri * Graham, North Carolina * Graham, Oklahoma * Graham, Texas * Graham, Washington Elsewhere * Graham Land, Antarctica * Graham Island (Mediterranean Sea), British name for a submerged volcanic island ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Richard Jozsa
Richard Jozsa is an Australian mathematician who holds the Leigh Trapnell Chair in Quantum Physics at the University of Cambridge. He is a fellow of King's College, Cambridge, where his research investigates quantum information science. A pioneer of his field, he is the co-author of the Deutsch–Jozsa algorithm and one of the co-inventors of quantum teleportation. Education Jozsa received his Doctor of Philosophy degree on twistor theory at Oxford, under the supervision of Roger Penrose. Career and research Jozsa has held previous positions at the University of Bristol, the University of Plymouth and the Université de Montréal. Awards and honours His work was recognised in 2004 by the London Mathematical Society with the award of the Naylor Prize for 'his fundamental contributions to the new field of quantum information science'. Since 2016, Jozsa is a member of the Academia Europaea The Academia Europaea is a pan-European Academy of Humanities, Letters, Law, and S ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Counterfactual Definiteness
In quantum mechanics, counterfactual definiteness (CFD) is the ability to speak "meaningfully" of the definiteness of the results of measurements that have not been performed (i.e., the ability to assume the existence of objects, and properties of objects, even when they have not been measured). The term "counterfactual definiteness" is used in discussions of physics calculations, especially those related to the phenomenon called quantum entanglement and those related to the Bell inequalities. In such discussions "meaningfully" means the ability to treat these unmeasured results on an equal footing with measured results in statistical calculations. It is this (sometimes assumed but unstated) aspect of counterfactual definiteness that is of direct relevance to physics and mathematical models of physical systems and not philosophical concerns regarding the meaning of unmeasured results. "Counterfactual" may appear in physics discussions as a noun. What is meant in this context is "a ... [...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] |
Isaac Newton Institute
The Isaac Newton Institute for Mathematical Sciences is an international research institute for mathematics and its many applications at the University of Cambridge. It is named after one of the university's most illustrious figures, the mathematician and natural philosopher Sir Isaac Newton and occupies one of the buildings in the Cambridge Centre for Mathematical Sciences. History After a national competition run by SERC, the Science and Engineering Research Council (now known as EPSRC Engineering and Physical Sciences Research Council), this institute was chosen to be the national research institute for mathematical sciences in the UK. It opened in 1992 with support from St John's College and Trinity College. St. John's provided the land and a purpose-built building, Trinity provided running costs for the first five years and the London Mathematical Society provided other support. Shortly afterwards at the institute, the British mathematician Andrew Wiles announced hi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Birkbeck, University Of London
, mottoeng = Advice comes over nightTranslation used by Birkbeck. , established = , type = Public research university , endowment = £4.3 m (2014) , budget = £109 million (2015) , parent = University of London , staff = , president = Baroness Bakewell , chancellor = The Princess Royal (University of London) , vice_chancellor = Wendy Thomson (University of London) , head_label = Master , head = David S Latchman , students = () , undergrad = () , postgrad = () , location = London, England, United Kingdom , coordinates = , colours = , mascot = , nickname = , affiliations = ACU European University AssociationRoyal Academy of Dramatic ArtUniversiti ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Mach–Zehnder Interferometer
The Mach–Zehnder interferometer is a device used to determine the relative phase shift variations between two collimated beams derived by splitting light from a single source. The interferometer has been used, among other things, to measure phase shifts between the two beams caused by a sample or a change in length of one of the paths. The apparatus is named after the physicists Ludwig Mach (the son of Ernst Mach) and Ludwig Zehnder; Zehnder's proposal in an 1891 article was refined by Mach in an 1892 article. Demonstrations of Mach–Zehnder interferometry with particles other than photons (particles of light) had been demonstrated as well in multiple experiments. The versatility of the Mach–Zehnder configuration has led to its being used in a wide range of fundamental research topics in quantum mechanics, including studies on counterfactual definiteness, quantum entanglement, quantum computation, quantum cryptography, quantum logic, Elitzur–Vaidman bomb tester, the quant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Superposition
Quantum superposition is a fundamental principle of quantum mechanics. It states that, much like waves in classical physics, any two (or more) quantum states can be added together ("superposed") and the result will be another valid quantum state; and conversely, that every quantum state can be represented as a sum of two or more other distinct states. Mathematically, it refers to a property of solutions to the Schrödinger equation; since the Schrödinger equation is linear, any linear combination of solutions will also be a solution(s) . An example of a physically observable manifestation of the wave nature of quantum systems is the interference peaks from an electron beam in a double-slit experiment. The pattern is very similar to the one obtained by diffraction of classical waves. Another example is a quantum logical qubit state, as used in quantum information processing, which is a quantum superposition of the "basis states" , 0 \rangle and , 1 \rangle . Here , 0 \r ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Quantum Zeno Effect
The quantum Zeno effect (also known as the Turing paradox) is a feature of quantum-mechanical systems allowing a particle's time evolution to be slowed down by measuring it frequently enough with respect to some chosen measurement setting. Sometimes this effect is interpreted as "a system cannot change while you are watching it". One can "freeze" the evolution of the system by measuring it frequently enough in its known initial state. The meaning of the term has since expanded, leading to a more technical definition, in which time evolution can be suppressed not only by measurement: the quantum Zeno effect is the suppression of unitary time evolution in quantum systems provided by a variety of sources: measurement, interactions with the environment, stochastic fields, among other factors. As an outgrowth of study of the quantum Zeno effect, it has become clear that applying a series of sufficiently strong and fast pulses with appropriate symmetry can also ''decouple'' a system ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Interference (wave Propagation)
In physics, interference is a phenomenon in which two waves combine by adding their displacement together at every single point in space and time, to form a resultant wave of greater, lower, or the same amplitude. Constructive and destructive interference result from the interaction of waves that are correlated or coherent with each other, either because they come from the same source or because they have the same or nearly the same frequency. Interference effects can be observed with all types of waves, for example, light, radio, acoustic, surface water waves, gravity waves, or matter waves. Etymology The word ''interference'' is derived from the Latin words ''inter'' which means "between" and ''fere'' which means "hit or strike", and was coined by Thomas Young in 1801. Mechanisms The principle of superposition of waves states that when two or more propagating waves of the same type are incident on the same point, the resultant amplitude at that point is equal to th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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