Quantum teleportation , or entanglement assisted teleportation , is a process by which a qubit the basic unit of quantum information can be transmitted exactly in principle from one location to another, without the qubit being transmitted through the intervening space. It is useful for quantum information science quantum information processing , however it does not immediately transmit Classical information Classical versus quantum information classical information , and therefore cannot be used for communication at superluminal faster than light speed. Quantum teleportation is unrelated to the common ... Quantum State via Dual Classical and Einstein Podolsky Rosen Channels , Phys. Rev. Lett. 70 , 1895 1899 1993 http www.research.ibm.com quantuminfo teleportation teleportation.html online . ref It was first ... http www.nature.com nature journal v390 n6660 full 390575a0.html title Experimental quantum teleportation ... Protocol Image Quantum teleportation diagram.PNG 300px thumb right Diagram for quantum teleportation of a photon The prerequisites for quantum teleportation are a qubit that is to be teleported, a conventional ... , and means of generating an Quantum entanglement entangled Bell state EPR pair of qubits, performing a Bell measurement on the EPR pair, and manipulating the quantum state of one of the pair. The protocol ... for example, quantum state math phi rangle math of a photon is performed, yielding two ... the correct one of four possible quantum states. A qubit identical to that chosen for teleportation for example, quantum state math phi rangle math of a photon results. Experimental results Work ... an Unknown Pure Quantum State via Dual Classical and Einstein Podolsky Rosen Channels author D ... cite web url http www.nature.com nature journal v430 n7002 full 430849a.html title Quantum teleportation ... ref The longest distance yet claimed to be achieved for quantum teleportation is convert 16 km mi abbr ... cite web url http www.physorg.com news193551675.html title Quantum teleportation achieved over ... more details
Unreferenced date December 2008 Quantum levels are fixed levels with a logarithmic scale logarithmic , descending quantum pattern in the visible spectrum of light that can be observed through a spectrometer while looking at intense flows of electricity through the various halides on the periodic table in a vacuum tube . They also have some use in chemistry when dealing with the movement of electron s to different atomic orbital orbital levels around the atom and the energy levels involved in such action. Quantum mechanics Absorption spectrum Emission spectrum Category Quantum mechanics quantum stub ... more details
Context date October 2009 The word quantum refers to the idea of interactions and discrete energy levels of particles at the subatomic level quantum mechanics . Quantum mechanics is a very deep topic, and seeks to describe the state of being of a physical system. The quantum world goes against traditional laws of physics and opens new dimensions of study and possibility. A quantum sensor therefore is an influencing system that can measure the effect of the quantum state of another physical or particle system on itself. The mere act of measurement influences the quantum state and alters the probability and uncertainty associated with its state during measurement. A quantum sensor is a device that exploits quantum correlations, such as quantum entanglement , to achieve a sensitivity or resolution that is better than can achieved using only classical systems. ref http merlin.fic.uni.lodz.pl concepts 2005 3 4 2005 3 4 225.pdf K.T.Kapale, et al., Concepts of Physics 2 2005 225 . ref The Defense Advanced Research Projects Agency has recently When date August 2011 launched a research program in optical quantum sensors that seeks to exploit ideas from quantum metrology and quantum imaging , such as quantum lithography and the NOON state , in order to achieve these goals with optical sensor systems such as lidar . ref http www.darpa.mil sto space qsp.html DARPA Quantum Sensor Program . ref ref https www.fbo.gov index?id 9bafd20629bf798e1b084fb2582a4b34 BROAD AGENCY ANNOUNCEMENT BAA 07 22 Quantum Sensors ref Quantum sensor is also a term used in other settings where entangled quantum systems are exploited to make better atomic clocks ref http link.aps.org abstract PRA v54 pR4649 J.J.Bollinger, et al., Phys. Rev. A 54 1996 R4649 . ref or more sensitive magnetometers . ref http link.aps.org abstract PRL v93 e173002 M.Auzinsh et al., Phys. Rev. Lett. 93 2004 173002 . ref ref http link.aps.org ... References Reflist Category Quantum information science Category Quantum mechanics ... more details
Orphan date November 2007 A quantum instrument is a quantum operation with both classical and quantum outputs. It combines the concepts of measurement and quantum operation. Description Usually it is implemented as a weighted collection of completely positive maps the sum of which is trace preserving. Quantum Instrument collection math mathcal E k math acts as math rho AB rightarrow tilde rho AA B sum k mathcal E k left rho AB right otimes vert k rangle langle k vert A math A quantum instrument is more general than a quantum operation because it records the outcome k of which operator acted on the state. References No footnotes date July 2009 E. Davies, J. Lewis. An operational approach to quantum probability, Comm. Math. Phys., vol. 17, pp. 239 260, 1970. http arxiv.org abs quant ph 0306078v1 Distillation of secret key paper http arxiv.org abs quant ph 0501045 Another paper which uses the concept DEFAULTSORT Quantum Instrument Category Quantum mechanics ... more details
A quantum limit in physics is a limit on measurement accuracy at quantum scales ref Vladimir Borisovich Braginski and Farid Ya. Khalili. Quantum Measurement. 1995. ref . Depending on the context, the limit may be absolute such as the Heisenberg limit , or it may only apply when the experiment is conducted with naturally occurring quantum state s e.g. the standard quantum limit in interferometry and can be circumvented with advanced state preparation and measurement schemes. The terms quantum limit and standard quantum limit are sometimes used interchangeably. Usually, quantum limit is a general term which refers to any restriction on measurement due to quantum effects, while the standard quantum limit in any given context refers to a quantum limit which is ubiquitous in that context. Examples In the context of interferometry or other optical measurements, the standard quantum limit usually refers to the minimum level of quantum noise which is obtainable without Squeezed coherent state squeezed states . ref M. T. Jaekel and S. Reynaud, Quantum limits in interferometric measurements , Europhys. Lett. 13, 301. 1990. ref There is additionally a quantum limit for phase noise , reachable only by a laser at high noise frequencies. In spectroscopy , the shortest wavelength in an X ray spectrum is called the quantum limit. ref Donald Stover Piston, The Polarization of X rays from Thin Targets. 1935. ref Misleading relation to the classical limit Note that due to an overloading of the word limit , the classical limit is not the opposite of the quantum limit. In quantum limit , limit is being used in the sense of a physical limitation e.g. the Armstrong limit . In classical limit , limit is used in the sense of a Limit mathematics limiting process ref Note that there is no simple rigorous mathematical limit which fully recovers classical mechanics from quantum mechanics, the Ehrenfest theorem notwithstanding. ref . See also Classical limit Heisenberg limit Relativistic limit References ... more details
Quantum mechanics cTopic Background Quantum topology is a branch of mathematics that connects quantum mechanics with low dimensional topology . Dirac notation provides a viewpoint of quantum mechanics which becomes amplified into a framework that can embrace the amplitudes associated with topological space s and the related embedding of one space within another such as knots and links in three dimensional space. This Bra ket notation of kets and bras can be generalised, becoming maps of vector space s associated with topological space s that allow tensor product s. ref Quantum Topology and Quantum Computing by Louis H. Kauffman ref Topological Tangle mathematics entanglement involving Link knot theory linking and Braid theory braiding can be intuitively related to quantum entanglement . ref Quantum Topology and Quantum Computing by Louis H. Kauffman ref See also Topological quantum field theory References Quantum topology by Louis H. Kauffman and Randy A. Baadhio, World Scientific Publishing Co Pte Ltd, 1993 reflist External links http www.ems ph.org journals journal.php?jrn qt Quantum Topology at EMS Publishing House. Category Quantum mechanics Category Topology ... more details
for the journal with this title Historical Social Research No footnotes date November 2011 In quantum mechanics , quantum information is physical information that is held in the state of a quantum system . The most popular unit of quantum information is the qubit , a two level quantum system. However, unlike classical digital states which are discrete , a two state quantum system can actually be in a quantum superposition superposition of the two states at any given time. Quantum information differs ... quantum computation that the differentiation occurs. The ability to manipulate quantum information ... secure transmission of information. Quantum information processing is the most general field that is concerned with quantum information. There are certain tasks which classical computer s cannot perform efficiently that is, in polynomial time according to any known algorithm. However, a quantum ... speed up over the best possible classical algorithm. Quantum information, and changes in quantum information ... ensemble of quantum mechanical systems with the density matrix math rho math , it is given ... theory can also be generalized to the quantum case, such as http www.mi.ras.ru holevo eindex.html Holevo entropy and the conditional quantum entropy . Quantum information theory The theory of quantum ... theory to the quantum world. Quantum information theory aims to answer the following question blockquote What happens if information is stored in a state of a quantum system? blockquote One of the strengths .... However, this is not the case for quantum information it is not possible, for example, to write ..., quantum mechanics does not allow us to read out the state of a quantum system with arbitrary precision. The existence of Bell state Bell correlations between Two state quantum system quantum systems cannot be converted into classical information. It is only possible to transform quantum information between quantum systems of sufficient information capacity. The information content of a message ... more details
Quantum phases are quantum states of matter at zero temperature. Even at zero temperature a quantum mechanical system has quantum fluctuations and therefore can still support phase transitions. As a physical parameter is varied, quantum fluctuations can drive a phase transition into a different phase of matter. An example of a canonical quantum phase transition is the well studied Superconductor Insulator Transition in disordered thin films which separates two quantum phases having different symmetries. Quantum magnets provide another example of QPT. The discovery of new quantum phases is a pursuit of many scientists. These phases of matter exhibit properties and symmetries which can potentially be exploited for technological purposes and the benefit of mankind. The difference between these states and classical states of matter is that classically, materials exhibit different phases which ultimately depends on the change in temperature and or density or some other macroscopic property of the material whereas quantum phases can change in response to a change in a different type of order parameter which is instead a parameter in the hamiltonian of the system much unlike the classical case of the system at zero temperature temperature does not have to change. The order parameter plays a role in quantum phases analogous to its role in classical phases. Some quantum phases are the result of a superposition of many other quantum phases. See also Quantum phase transitions Phase transitions Classical phase transitions Quantum critical point References Cite book last Sachdev first Subir title Quantum Phase Transitions publisher Cambridge University Press date 2000 isbn 0521004543S Cite book last Carr first Lincoln D. title Understanding Quantum Phase Transitions publisher CRC Press date 2010 isbn 9781439802519 Category Condensed matter physics Category Quantum mechanics ... more details
In physics, quantum dynamics is the quantum version of classical dynamics . Quantum dynamics deals with the motions, and energy and momentum exchanges of systems whose behavior is governed by the laws of quantum mechanics . ref Cite web url http www.quantiki.org content centre quantum dynamics griffith university title Centre for Quantum Dynamics, Griffith University author Joan Vaccaro date 2008 06 26 work Quantiki publisher accessdate 2010 01 25 ref ref Cite book publisher Springer isbn 0387229647, 9780387229645 last Wyatt first Robert Eugene authorlink Robert E. Wyatt coauthors Corey J. Trahan title Quantum dynamics with trajectories year 2005 ref Quantum dynamics is relevant for burgeoning fields, such as quantum computing and atomic optics . In mathematics, quantum dynamics is the study of the mathematics behind quantum mechanics . ref Cite book publisher Springer isbn 3540407235, 9783540407232 last Teufel first Stefan title Adiabatic perturbation theory in quantum dynamics date 1821 01 01 ref Specifically, as a study of dynamics , this field investigates how quantum mechanical observables change over time. Most fundamentally, this involves the study of one parameter automorphisms of the algebra of all bounded operators on the Hilbert space of observables which are self adjoint operators . These dynamics were understood as early as the 1930s, after Wigner , Marshall Stone Stone , Erwin Hahn Hahn and Hellinger worked in the field. Recently, mathematicians in the field have studied irreversible quantum mechanical systems on von Neumann algebra s. ref Cite book publisher AMS Bookstore isbn 0821832158, 9780821832158 last Price first Geoffrey L. title Advances in quantum dynamics year 2003 ref See also Perturbation theory Semigroups Pseudodifferential operators Brownian motion Dilation theory Quantum probability Free probability References references physics stub Category Quantum mechanics he ... more details
A quantum robot is a hypothetical mobile quantum nanosystem, which could be built using nanotechnology . It would include a quantum computer and special devices to allow it to interact with its environment. It could take measurements or realize specified changes in the quantum states of the environment. The concept of a quantum robot was suggested by Paul Benioff in 1997 98. See also Quantum cellular automata Quantum finite automata References cite arXiv eprint quant ph 9802067v2 doi 10.1103 PhysRevA.58.893 author1 Paul Benioff title Quantum Robots and Environments class quant ph year 1998 cite journal url http physics.princeton.edu kirkmcd examples QM benioff sm 23 407 98.pdf author Paul Benioff title Some foundational aspects of quantum computers and quantum robots journal Superlattices and Microstructures volume 23 issue 3 4 year 1998 pages 407 417 cite arXiv eprint quant ph 9807032 author1 Paul Benioff title Quantum Robots Plus Environments class quant ph year 1998 cite arXiv eprint quant ph 9706012 author1 Paul Benioff title Quantum Robots and Quantum Computers class quant ph year 1997 cite arXiv eprint quant ph 0506155 doi 10.1017 S0263574705002596 author1 Dao Yi Dong author2 Chun Lin Chen author3 Chen Bin Zhang author4 Zong Hai Chen title Quantum Robot Structure, Algorithms and Applications class quant ph year 2005 DEFAULTSORT Quantum Robot Category Quantum information science Category Nanotechnology ru ... more details
no footnotes date September 2010 Quantum nanoscience is the research area and the branch of nanotechnology and physics that uses methods of quantum mechanics to the design of new types of nanodevices and nanoscale materials, where functionality and structure of quantum nanodevices are described through quantum phenomena and principles such as discretisation , quantum superposition superposition and entanglement . As a well known quantum nanodevice is a quantum computer , which can be considers as a quantum system for computation that makes direct use superposition and entanglement, to perform quantum operations with quantum states. As an interesting possible quantum nanodevice, which should be built by nanotechnology, is a quantum robot . The other example is quantum nanomechanics that is a new field engendered by the ability to create mechanical nanoresonators with very high frequencies. See also Quantum computer Quantum robot Mesoscopic physics References Reflist http homepage.mac.com gjmilburn Quantum nanoscience 2.pdf G. J. Milburna, M. J. Woolleya Quantum nanoscience Contemporary Physics, Vol. 49, No. 6, 2008 413 433. http pra.aps.org abstract PRA v58 i2 p893 1 P. Benioff, Quantum Robots and Environments , Phys. Rev. A 58 1998 893 904. http arxiv.org abs quant ph 9802067 arXiv quant ph 9802067 http arxiv.org abs quant ph 0506155 Dao Yi Dong, et al., Quantum Robot Structure ... structure Documents Research 20Papers PPQT.pdf Deutsch D., Physics, Philosophy, and Quantum Technology , in the Proceedings of the Sixth International Conference on Quantum Communication, Measurement ... s Machines The Quantum Technology Reshaping Everyday Life ISBN 0716731061 0 7167 3106 1 http www.worldscinet.com ijn 08 0804n05 S0219581X09005517.html V.E. Tarasov, Quantum Nanotechnology ... RecordID ORG1240649 Language en Department of Quantum Nanoscience Kavli Institute of Nanoscience http www.ausnano.net index.php?page groups&group 100 Quantum nanoscience Group The Australian Research ... more details
unreferenced date January 2009 Expert subject Physics date November 2008 quantum field theory In theoretical physics , quantum physical cosmology cosmology is a field attempting to study the effect of quantum mechanics on the formation of the universe, or its early evolution, especially just after the Big Bang . Despite many attempts, such as the Wheeler deWitt equation , the field remains a rather speculative branch of quantum gravity . The area with the most current research is loop quantum cosmology , based on loop quantum gravity . An important problem in this field is the origin of physical information in the universe. See also Minisuperspace References there are quite a few potential references on the talk page for anyone interested in citing the article or building up its content Empty section date July 2010 External links http www.damtp.cam.ac.uk user gr public qg qc.html A Layman s Explanation of Quantum Cosmology http arxiv.org abs 0909.2566 Lectures on Quantum Cosmology by J.J. Halliwell quantum gravity Category Quantum gravity Category Physical cosmology quantum stub es Cosmolog a cu ntica eu Kosmologia kuantikoa fa fr Cosmologie quantique it Oltre il modello standard del Big Bang ja ru fi Kvanttikosmologia ... more details
Quantum fingerprinting is a proposed technique that uses a quantum computer to generate a string with a similar function to the cryptographic hash function . If unconditional guarantees of security are needed, and if it is impractical for the communicating parties to arrange to share a secret that can be used in a Carter Wegman MAC , this technique might one day be faster than classical techniques given a quantum computer with 5 to 10 qubit s. However, these circumstances are very unusual and it is unlikely the technique will ever have a practical application it is largely of theoretical interest. See also Quantum cryptography Quantum digital signature External links http arxiv.org abs quant ph 0102001 Original paper by Buhrman et al. from 2001 Category Cryptographic hash functions Category Quantum information science ... more details
unreferenced date June 2011 Coupling in molecules Quantum Coupling is an effect in quantum mechanics in which two or more quantum systems are bound such that a change in one of the quantum states in one of the systems will cause an instantaneous change in all of the bound systems. It is a state similar to quantum entanglement but whereas quantum entanglement can take place over long distances quantum coupling is restricted to quantum scales. Quantum coupling in action Trapped ion quantum computers utilize the quantum coupling effect by suspending particles representing qubits in an array of ion traps. These particles are then induced into a state of quantum coupling by using optical pumping by a laser. Information can be stored in this state by coupling two or more qubits. While the individual particles may fluctuate their values, the quantum states of the two qubits remain locked in relation to each other, via Coulomb force . Any action by one of the coupled ions instantaneously alters the other to maintain the relative value. This allows the computer to hold information despite the instability of the individual particles. Other examples In benzene , C sub 6 sub H sub 6 sub , the charges of the individual carbon atoms exhibit coupling. There are three double bonds and three single bond s in alternating positions around the ring. The measurement of the energy in any individual bond will result in a puzzling result resembling an impossible one and a half bond . This is because the bonds are in a quantum superposition of double and single bonds at any particular bond position. The coupling effect causes the charge at all points on the ring to be altered when a bond at any one point is altered, in order to maintain the relative charge between atoms . This results in an illusionary bond and a half bond between all 6 carbon atoms. Category Quantum mechanics sl Kvantna sklopitev ... more details
. Quantum I 1959 1st iteration was with a very basic aluminum body. Second iteration of the bodywork was only slightly more finished. This is the version it wears today. Quantum II Nearly identical to the Quantum I in every way. Both use a water cooled, three cylinder Saab two stroke engine. Quantum III Completely new design. Two built. Quantum IV 1964 Single seater formula car sold as a kit car . Intended for Sports Car Club of America s SCCA Formula S series. Quantum V 1965 Ginetta body. Saab ...Image SaabQuantum.jpg thumb 1963 Saab Quantum III. SAAB Quantum was a series of 5 SAAB automobile cars built in the USA . The earliest cars used Saab 93 two stroke cycle two stroke engines, transmissions and suspension. The later cars used Saab 96 drivetrains and suspension parts. The Quantum I was built in 1959, with a chassis Computer aided design computer engineered by Walter Kern at IBM in his spare time. It wore only the most basic bodywork at first. After initial testing and a race or two, it was replaced with moderately more complete bodywork which it still wears to this day. The Quantum ... H Modified class. They were pure prototypes and racing cars, never intended for production. The Quantum ... Saab Quantum IV rear image saabquantum4front.jpg Saab Quantum IV front image saabquantum4side.jpg Saab Quantum IV side gallery br clear all External links commons category Saab Quantum http www.webcitation.org query?url http www.geocities.com cjmills9 The Quantum Series.html&date 2009 10 25 17 23 00 New England Saab Association The Quantum Series http www.formulasaab.com Formula S register http ... zrFWq George Vapaa s Quantum Formula S restoration scrapbook it http www.saabnews.it 2011 04 la prima saab quantum i La prima Saab Quantum I Pictures http www.sandiegosaab.com images Red Conv Front.jpg Quantum III , http www.sandiegosaab.com html bud walt.htm Walter Kern right http photos.at speed.com Cars 1959 Quantum One SAAB H Mod 1959 Quantum I Saab Automobile Category Saab vehicles Quantum ... more details
Quantum cloning is the process that takes an arbitrary, unknown quantum state and makes an exact copy without altering the original state in any way. In Dirac notation , the process of quantum cloning is described by math U psi rangle A e rangle B psi rangle A psi rangle B math , where math U math is the actual cloning operation, math psi rangle A math is the state to be cloned, and math e rangle B math is the initial state of the copy. Quantum cloning is forbidden by the laws of quantum mechanics as shown by the no cloning theorem , which proves that there is no math U math that can perform the cloning operation for any arbitrary state math psi rangle A math . Though perfect quantum cloning is not possible, it is possible to perform imperfect cloning, where the copies have a non unit Fidelity of quantum states fidelity with the state being cloned. The quantum cloning operation is the best way to make copies of quantum information therefore cloning is an important task in quantum information processing, especially in the context of quantum cryptography. Researchers are seeking ways to build quantum cloning machines, which work at the so called quantum limit. The first cloning machine relied on stimulated emission to copy quantum information encoded into single photons. Teleportation, nuclear magnetic resonance, quantum amplification and superior phase conjugation have been some other methods utilized to realize a quantum cloning machine. References V. Buzek and M. Hillery, http xstructure.inr.ac.ru x bin theme3.py?level 1&index1 373537 Quantum cloning , Physics World 14 11 2001 ... abs quant ph 0205149 Experimental Quantum Cloning of Single Photons , Science 296 5568 2002 ... quant ph 011198 Approximate Quantum Cloning with Nuclear Magnetic Resonance , Phys. Rev. Lett 88 ... Conjugate Inputs , Phys. Rev. Lett 98 170503 2007 See also Quantum no deleting theorem Category Quantum mechanics Category Quantum information science quantum stub ... more details
Orphan date February 2009 A quantum sort is any sorting algorithm that runs on a quantum computer . Any comparison based quantum sorting algorithm would take at least math Omega n log n math steps ref cite conference author P. H yer, J. Neerbek, Y. Shi title Quantum complexities of ordered searching, sorting, and element distinctness booktitle 28th International Colloquium on Automata, Languages, and Programming pages 62 73 year 2001 url http www.springerlink.com content 25gl9elr5rxr3q6a http arxiv.org abs quant ph 0102078 Also in quant ph 0102078 ref , which is already achievable by classical algorithms. Thus, for this task, quantum computers are no better than classical ones. Do note, that in space bounded sorts, quantum algorithms outperform their classical counterparts. ref cite conference last Klauck first Hartmut title Quantum Time Space Tradeoffs for Sorting url http portal.acm.org citation.cfm?id 780553 booktitle Proceedings of the thirty fifth annual ACM symposium on Theory of computing year 2003 ref References this empty section displays references defined elsewhere reflist See also Bogosort , a sorting algorithm with a joke quantum implementation Category Sorting algorithms Category Quantum information science quantum computing sorting comp sci theory stub ... more details
In physics , a quantum mirage is a peculiar result in quantum chaos . Every system of quantum dynamical billiards will exhibit an effect called scarring , where the quantum probability density shows traces of the paths a classical billiard ball would take. For an elliptical arena, the scarring is particularly pronounced at the foci, as this is the region where many classical trajectories converge. The scars at the foci are colloquially referred to as the quantum mirage . The quantum mirage was first experimentally observed by Hari Manoharan, Christopher Lutz and Donald Eigler at the IBM Research IBM Almaden Research Center in San Jose, California in 2000. The effect is quite remarkable but in general agreement with prior work on the quantum mechanics of dynamical billiards in elliptical arenas. Quantum corral File The Well Quantum Corral .jpg thumb left The Well Quantum Corral 2009 by Julian Voss Andreae . Created using the 1993 experimental data by Lutz et al. , the gilded sculpture was pictured in a 2009 review of the art exhibition Quantum Objects in the journal Nature . ref cite journal first Philip last Ball year 2009 month 26 November title Quantum objects on show journal Nature volume 462 issue 7272 pages 416 url http www.nature.com nature journal v462 n7272 pdf 462416a.pdf ... of a quantum corral , a ring of atoms arranged in an arbitrary shape on a Substrate materials science substrate . The quantum corral was demonstrated in 1993 by Lutz, Donald Eigler Eigler , and Michael ... title Confinement of electrons to quantum corrals on a metal surface. journal Science volume 262 ... by the theory of quantum mechanics . The size and shape of the corral determine its quantum ... focus. Applications IBM scientists are hoping to use quantum mirages to construct atomic scale processors in the future. References Reflist http www.almaden.ibm.com almaden media mirage.html Quantum Mirage ... 0211607 Theory of Quantum Corrals and Quantum Mirages Category Quantum electronics es Espejismo cu ntico ... more details
quantumQuantum Darwinism is a theory explaining the emergence of the Classical physics classical world from the Quantum mechanics quantum world as due to a process of Charles Darwin Darwinian natural selection where the many possible quantum states are selected against in favor of a stable pointer state ... . A study in 2010 has provided preliminary supporting evidence of quantum Darwinism with scars of a quantum dot becoming a family of mother daughter states indicating they could stabilize into multiple pointer states. ref name urlNew evidence for quantum Darwinism found in quantum dots cite web url http www.physorg.com news192693808.html title New evidence for quantum Darwinism found in quantum dots format work accessdate 2010 05 12 ref Implications Along with Zurek s related theory of envariance , quantum Darwinism explains how the classical world emerges from the quantum world and proposes to answer the quantum measurement problem , the main interpretational challenge for quantum theory. The measurement problem arises because the quantum state vector, the source of all knowledge concerning quantum systems, evolves according to the Schr dinger equation into a linear superposition ... never experienced in our classical world. Quantum theory has traditionally treated this problem as being resolved by a non unitarity physics unitary transformation of the quantum state state vector at the time ... measurement value. The physical nature of the transition from the quantum superposition of states ... of quantum theory. Quantum Darwinism explains the transition of quantum systems from the vast ... Hubert Zurek Decoherence, einselection, and the quantum origins of the classical http hubcap.clemson.edu ... as a selection process, einselection , imposed on the quantum system through its continuous interactions with the environment. All quantum interactions, including measurements, but much more typically interactions with the environment such as with the sea of photons in which all quantum systems are immersed ... more details
No footnotes date April 2009 Quantum optics is a field of research in physics , dealing with the application of quantum mechanics to phenomena involving light and its interactions with matter . History of quantum optics Light is made up of particles called photons and hence inherently is grainy quantized . Quantum optics is the study of the nature and effects of light as quantized photons. The first ... between light and matter following these developments not only formed the basis of quantum optics but was also crucial for the development of quantum mechanics as a whole. However, the subfields of quantum mechanics dealing with matter light interaction were principally regarded as research into matter rather than into light hence one rather spoke of atom physics and quantum electronics ... became an important field, and the quantum mechanics underlying the laser s principles was studied now with more emphasis on the properties of light, and the name quantum optics became customary. As laser ... very fruitful, interest in quantum optics rose. Following the work of Paul Dirac Dirac in quantum field theory , George Sudarshan , Roy J. Glauber , and Leonard Mandel applied quantum theory to the electromagnetic ... of the coherent state as a quantum description of laser light and the realization that some states ... the first source of light which required a quantum description a single atom that emitted ... quantum state of light with certain advantages over any classical state, Squeezed coherent state ... of quantum entanglement , quantum teleportation , and recently, in 1995 quantum logic gate s. The latter are of much interest in quantum information theory , a subject which partly emerged from quantum optics, partly from theoretical computer science . Today s fields of interest among quantum ... oscillation , even shorter attosecond light pulses, use of quantum optics for quantum information , manipulation ... a sub field often called atom optics , coherent perfect absorber s, and much more. Research into quantum ... more details
The quantum yield of a radiation induced process is the number of times that a defined event occurs per photon absorbed by the system. The event may represent a chemical reaction, for example the decomposition of a reactant molecule center math Phi frac rm molecules decomposed rm photons absorbed math center Quantum Yield can also be defined for other events, such as fluorescence emission of photons in which case the quantum yield is defined by the equation center math Phi frac rm photons emitted rm photons absorbed math center Here, quantum yield is essentially the emission efficiency of a given fluorophore in this case. Example Quantum yield is used in modeling photosynthesis Skillman 2008 center math Phi frac rm mu mol CO 2 fixed rm mu mol photons absorbed math center See also Quantum efficiency Quantum Efficiency References reflist Skillman, J.B. 2008. Quantum yield variation across the three pathways of photosynthesis not yet out of the dark. Journal of Experimental Botany, 59 7 1647 1661 doi 10.1093 jxb ern029 DEFAULTSORT Quantum Yield Category Radiation Category Spectroscopy Category Photochemistry it Resa quantica uk ... more details
No footnotes date November 2009 Quantum noise is uncertainty of some physical quantity due to its quantum origin. In the case of number of particles photons or electrons , the quantum noise is also called shot noise . Most optical communications use amplitude modulation. In this case, the quantum noise appears as shot noise only. In the case of uncertainty of electric field in some laser s, the quantum noise is not just shot noise uncertainties of both amplitude and phase contribute to the quantum noise. This issue becomes important in the case of noise of a quantum amplifier , which preserves ... with energy of quantum comparable to the energy of a signal which is believed to be more robust with respect to additive noise than an amplitude modulation . Origin of quantum noise Quantum noise may ... suppressed. Generally, quantum noise can be considered as error of description of any physical system within classical not quantum theory. In an electric circuit, the random fluctuations of a signal due to discrete character of electrons can be called quantum noise ref name Zoller C. W. Gardiner and Peter Zoller , Quantum Noise , Springer Verlag 1991, 2000, 2004 ref . The random error of interferometric measurement of position due to discrete character of photons registered can be attributed to quantum noise. Even the uncertainty of position of a probe in probe microscopy may lead to quantum noise ... cases, quantum noise refers to the fluctuations of signal in extremely accurate optical systems with stabilized lasers and efficient detectors. Coherent states and noise of a quantum amplifier Although ... wave. Within quantum mechanics, such a wave can be approximated with a coherent state . At total ... error of measurement of intensity due the quantum noise is only of order of 10 sup 5 sup which is good precision for most of applications. Quantum noise becomes important at the amplification of a small signal. Roughly, the quantum uncertainty of the quadrature components of the field is amplified ... more details
In quantum computing , quantum walks are the quantum analogue of classical random walks . Like the classical ... positions, the walker in a quantum walk is in a quantum superposition superposition of positions. Like classical random walks, there are two types of quantum walks, discrete time quantum walks and continuous time quantum walks. Motivation Quantum walks are motivated by the widespread use of classical random walks in the design of randomized algorithms, and are part of several quantum algorithm s. For some oracular problems, quantum walks provide an exponential speedup over any classical algorithm ... Spielman D. A. Spielman , Exponential algorithmic speedup by quantum walk, Proc. 35th ACM Symposium ..., and Umesh Vazirani U. V. Vazirani , Quantum algorithms for hidden nonlinear structures, Proc. 48th IEEE Symposium on Foundations of Computer Science, pp. 395 404, 2007, arXiv 0705.2784. ref Quantum ... distinctness problem , ref Andris Ambainis , Quantum walk algorithm for element distinctness ... 2004. ref the triangle finding problem , ref F. Magniez, M. Santha, and Mario Szegedy M. Szegedy , Quantum ... J. Goldstone , and S. Gutmann, A quantum algorithm for the Hamiltonian NAND tree, Theory of Computing ... can also be viewed as a quantum walk algorithm. Relation to classical random walks Quantum walks ... to limiting distributions and due to the power of quantum interference they may spread significantly faster or slower than their classical equivalents. Continuous time Main Continuous time quantum walk Under particular conditions, continuous time quantum walks can provide a model for universal quantum ... abs 0806.1972 Universal Computation by Quantum Walk . ref Discrete time Expand section date December 2009 Image One dimensional quantum random walk.png thumb right Probability distribution resulting from one dimensional discrete time random walks. The quantum walk created using the Hadamard coin is plotted blue vs a classical walk red after 50 time steps. A quantum walk in discrete time is specified ... more details
In quantum information theory , quantum discord is a measure of nonclassical correlations between two subsystems of a quantum system. It includes correlations that are due to quantum mechanics quantum physical effects but do not necessarily involve quantum entanglement . The notion of quantum discord ... 2 K abstract abstract ref ref name olliver zurek 2001 Harold Ollivier and Wojciech H. Zurek, Quantum ... et al 2007 P1 Animesh Datta, Anil Shaji, Carlton M. Caves Quantum discord and the power of one qubit ... page 1 p. 1 ref by L. Henderson and Vlatko Vedral . ref L. Henderson and V. Vedral Classical, quantum ... that quantum correlations can be present in certain mixed separable states ref name giorda paris 2010 P1 Paolo Giorda, Matteo G. A. Paris Gaussian quantum discord , quant ph arXiv 1003.3207v2 ... page 1 p. 1 ref In other words, separability alone does not imply the absence of quantum effects. The notion of quantum discord thus goes beyond the distinction which had been made earlier between entangled versus separable non entangled quantum states. Definition and mathematical relations ... information I X Y . In mathematical terms, quantum discord is defined in terms of the quantum mutual information . More specifically, quantum discord is the difference between two expressions which ... , and the two expressions yield identical results. In the nonclassical case, the quantum physics analogy ... quantum entropy and math S rho A rho B math the conditional quantum entropy , respectively, for probability ... dependent quantum discord, which is asymmetrical in the sense that math mathcal D A rho math can ..., Caslav Brukner Necessary and sufficient condition for nonzero quantum discord , Phys. Rev. Lett ... in dependence on the chosen Matrix factorization Eigendecomposition eigenbasis therefore, in order for the quantum ... projective quantum measurement measurements onto the eigenbasis ref For a more detailed overview see for ex. Signatures of nonclassicality in mixed state quantum computation , Physical Review A vol. ... more details
mergefrom Quantum virtual machine discuss Talk Quantum programming Merger proposal date August 2009 Quantum programming is a set of computer programming language s that allow the expression of quantum algorithm s using high level constructs. The point of quantum languages is not so much to provide a tool for programmers, but to provide tools for researchers to understand better how quantum computation works and how to formally reason about quantum algorithms. Efforts are underway to develop functional programming languages for quantum computing . Examples include Selinger s QPL ref name qpl http ... http sneezy.cs.nott.ac.uk qml QML A Functional Quantum Programming Language Bot generated title ref . Higher order quantum programming languages, based on lambda calculus , have been proposed by van Tonder ref http epubs.siam.org SICOMP volume 33 art 43216.html A Lambda Calculus for Quantum Computation ... simon quantumQuantum Programming Languages Survey has more information on the current state of research and a comprehensive bibliography of resources. Imperative quantum programming languages Quantum pseudocode Quantum pseudocode proposed by E. Knill is the first formalised language for description of quantum algorithm s was introduced and, moreover, it was tightly connected with a model of quantum machine called Quantum Random Access Machine QRAM . Quantum computing language http tph.tuwien.ac.at oemer qcl.html QCL Quantum Computation Language is one of the first implemented quantum programming languages . Its syntax resembles syntax of the C programming language and classical data type s are similar to data types in C. You can combine a classical code and a quantum code in one source code. The basic built in quantum data type in QCL is the qureg quantum register . It can be interpreted as an array of qubits quantum bits . qureg x1 2 2 qubit quantum register x1 qureg x2 2 2 qubit quantum register x2 H x1 Hadamard operation on x1 H x2 1 Hadamard operation on the first ... more details
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