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Topic: Bell measurement


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  Bell's theorem - Wikipedia, the free encyclopedia
Bell's theorem is often presented in the context of the foundations of quantum mechanics, since quantum mechanics predicts cases in which a Bell inequality is infringed.
John Bell's ground-breaking mid-1960s papers examined both John von Neumann's 1932 proof of the incompatibility of hidden variables with QM and Albert Einstein and his colleagues' seminal 1935 paper on the subject.
Bell's inequalities are tested by "coincidence counts" from a Bell test experiment such as the optical one shown in the diagram.
en.wikipedia.org /wiki/Bell's_Theorem   (2937 words)

  
 Bell measurement - Wikipedia, the free encyclopedia
The Bell measurement is an important concept in quantum information science: It is a joint quantum-mechanical measurement of two qubits that determines in which of the four Bell states the two qubits are in.
If the qubits were not in a Bell state before, they get projected into a Bell state (according to the projection rule of quantum measurements), and as Bell states are entangled, a Bell measurement is an entangling operation.
In Bell measurements of ion qubits in ion trap experiments, the distinction of all four states is possible.
en.wikipedia.org /wiki/Bell_measurement   (174 words)

  
 STANDING - Online Information article about STANDING
Measurement of the Discharge of Rivers.—The area of cross others they diminish.
In wider streams the use of ropes to mark the length of run is impossible, and recourse must be had to box sextants or theodolites to mark the path of the floats.
Now let the meter be towed over a measured distance L, and let N be the revolutions of the meter and t the time of transit.
encyclopedia.jrank.org /SOU_STE/STANDING.html   (8091 words)

  
 John Bell and the most profound discovery of science (December 1998) - Physics World - PhysicsWeb
Bell was especially interested in theoretical physics and a year later he was able to graduate for a second time, obtaining a first in mathematical physics in 1949.
Bell's numerical calculations had shown signs of the strong focusing principle, and when it was established formally in 1952 he rapidly became an expert and acted as a consultant to the team designing the Proton Synchrotron at CERN in Geneva.
Bell and his wife were both long-term vegetarians, and in his version of Schrödinger's cat paradox, the two states of the cat are being hungry or not hungry, rather than being dead or alive.
physicsweb.org /articles/world/11/12/8   (5306 words)

  
 The EPR Paradox and Bell's Inequality Principle
QM suggests that if say the measurement of the photon 1 x-spin happens first, then this measurement must instantaneously force photon 2 into a state of ill-defined y-spin, even though it is light years away from photon 1.
Measure the spin in one axis of one particle and the spin in another axis of the other photon.
Let n[x+, y+] be the designation for "the number of measurements of pairs of photons in which the first photon measured x+, and the second photon measured y+." Use a similar designation for the other possible results.
math.ucr.edu /home/baez/physics/Quantum/bells_inequality.html   (2076 words)

  
 Fundamentals of quantum information (March 1998) - Physics World - PhysicsWeb
In working with Bell states it is common to refer to four unitary operations: the phase shift, the bit flip, the combined phase-shift/bit-flip, and the identity operator, which does not change the state on which it operates.
Alice then performs a joint Bell-state measurement on the teleportee (the photon she wants to teleport) and one of the ancillary photons, and randomly obtains one of the four possible Bell results.
It is essential to understand that the Bell-state measurement performed by Alice projects the teleportee qubit and her ancillary photon into a state that does not contain any information about the initial state of the teleportee.
physicsweb.org /articles/world/11/03/9/1   (3345 words)

  
 Quantum teleportation - free-definition   (Site not responding. Last check: 2007-10-04)
If Alice now has a particle which she wants to teleport to Bob, she does a so-called Bell measurement on the particle to be sent and on particle I. The Bell measurement (for details see the article on it) projects Alice's two particle into one of the four Bell states.
The two measured particles are afterwards in a known entangled state, specified by the measurement result, and the particle to be sent has lost its former state.
This is because the outcome of the Bell measurement is perfectly random and hence the rotation of the teleported state (see above) is random as well.
www.free-definition.com /Quantum-teleportation.html   (1677 words)

  
 Realistic theories and randomness
Often Bell's result is presented as showing that quantum mechanics is not a realistic theory rather than showing that it is nonlocal.
Measuring the position of one particle puts constraints on the position of the other particle.
The probabilistic element in the measurements is sufficient to mask any information about which measurement influenced which distant observation, but the mathematics requires that one of the two measurements did influence the more distant observation.
www.mtnmath.com /whatr72h/node79.html   (810 words)

  
 Bell Current Sensors & Measurement/Meters&Probes
The Model CLN-25 is a closed loop Hall effect current sensor that accurately measures dc and ac currents and provides electrical isolation between the current carrying conductor and the output of the sensor.
Models CLN-50 and CLN-100 are closed loop Hall effect current sensors that accurately measure dc and ac current and provide electrical isolation between the current carrying conductor and the output of the sensor.
Models CLO-300 and CLO-500 are closed loop Hall effect sensors that accurately measure dc and ac currents and provide electrical isolation between the current carrying conductor and the output of the sensor.
omnicontrols.com /lists/FWBell_CurrentMeasurement.html   (1504 words)

  
 Bell's Theorem
The second condition means that one can "separate" the probabilities for measurements on A and B (ie: the probabilities for measurements at A and B are two independent functions).
For example, if we are measuring the polarization of light or the spin of a particle, then then a would define the projection axis of the spin or the polarization.
Notice that the result of a measurement on particle 1 is not affected by the orientation of detector "B" nor does it depend on any measurement which might have taken place on particle 2 (ie.
roxanne.roxanne.org /epr/bell.html   (784 words)

  
 Quantum Mechanics: Fundamentals
Identical particles are discussed, with a treatment of second quantization and an introduction to Bose--Einstein condensation, and the last chapter is a brief introduction to relativistic quantum mechanics, including the Dirac equation, the electromagnetic interaction of a Dirac particle, the scattering of ultra-relativistic electrons and a treatment of bound states in a Coulomb field.
Bell’s theorem is analysed in some detail; also included are the Clauser--Horne inequality and the experimental test of the Bell inequality by Aspect.
The conclusion is that after a measurement, interference terms are ‘effectively’ absent; the set of ‘one-to-one correlations between states of the apparatus and the object’ has the same form as that of everyday statistics and is thus a probability distribution.
stacks.iop.org /0305-4470/37/3073   (2392 words)

  
 A possible loophole in the theorem of Bell -- Hess and Philipp 98 (25): 14224 -- Proceedings of the National Academy of ...
The celebrated inequalities of Bell are based on the assumption that local hidden parameters exist.
The Bell theorem is based on a mathematical model of the EPR experiments.
Bell (8) defines the following parameter sets that are in the backward light cone, as defined by relativity and as illustrated
www.pnas.org /cgi/content/full/98/25/14224   (2456 words)

  
 Quantum Teleportation
Alice makes an appropriate projective measurement (Bell measurement) of the unknown state together with her component of the shared entangled state.
The result of this measurement is a random piece of classical information which Alice sends to Bob over their classical communication channel.
Notice that the input state is destroyed by Alice's projective measurement, so that teleportation does not result in "cloning" of a quantum state.
www.its.caltech.edu /~qoptics/teleport.html   (532 words)

  
 TelePOVM—A generalized quantum teleportation scheme
To teleport this state to Bob, she performs a joint measurement on the two particles that are in her hands: the unknown quantum state and her share of the EPR pair.
If the measurement is chosen in advance and Alice tells Bob its one-bit outcome, he can know precisely the state of the qubit in his hands without having to measure it.
A measurement that checks whether the state is in the subspace spanned by 00> and 11>, or in the subspace spanned by 01> and 10>.
www.research.ibm.com /journal/rd/481/brassard.html   (6196 words)

  
 Internet Traffic: Measurement, Analysis, Modeling, and Generation
We measure, study, and model the characteristics of Internet traffic for device design, network performance monitoring, and traffic engineering.
Our statistical models generate requests for connections from a cloud of users; the requests are given to a network model that uses the source code of TCP from the BSD kernel to generate packets.
As part of this DARPA funded work our Helios team from Bell Labs Research, Lucent Optical Network Group, NCNI Research, and UNC Computer Science, is collecting and analyzing high-speed Internet traffic data on the NCNI gigapop, and we are implementing a S-Net-Helios environment at link speeds of up to 2.5 gigabits/second.
cm.bell-labs.com /cm/ms/departments/sia/InternetTraffic   (595 words)

  
 Cavity Ring-Down Spectroscopy: A New Approach for Difficult-to-Measure Atmospheric Trace Gases
Observation of the absorption of light is an age-old method for measuring concentration of important compounds in the atmosphere.
The measurement of the rate of the light intensity decrease in the presence and absence of the absorption gives a direct and very sensitive determination of the absorber's concentration.
Until recently, measurement of NO3 was cumbersome and observation of N2O5 in the lower atmosphere was impossible.
cires.colorado.edu /science/reviews/noaa/2002/abstracts/05brown.html   (407 words)

  
 Bohmian Mechanics and the Foundations of Quantum Mechanics
The first charge against "measurement", in the fundamental axioms of quantum mechanics, is that it anchors the shifty split of the world into "system" and "apparatus".
When it is said that something is "measured" it is difficult not to think of the result as referring to some preexisting property of the object in question.
It was soon abandoned and utterly ignored until rediscovered a quarter century later by David Bohm, who showed how it resolved the measurement problem and accounted for the reduction of the wave packet.
www.math.rutgers.edu /~oldstein/quote.html   (846 words)

  
 Teleporting a Qubit   (Site not responding. Last check: 2007-10-04)
pair onto a Bell state is thus accomplished by placing detectors in each of the outputs of the beam splitter and registering simultaneous detections.
The Bell basis measurement was based on a procedure originally suggested by Brassard.
In fact this is what measurement really is. So, by allowing carbon nuclei quantum states to decohere, they effectively used the environment to perform the projective measurement for them.
beige.ucs.indiana.edu /B679/node71.html   (1244 words)

  
 Quantum Equilibrium And The Origin Of Absolute Uncertainty (ResearchIndex)
The quantum formalism is a "measurement" formalism---a phenomenological formalism describing certain macroscopic regularities.
We argue that it can be regarded, and best be understood, as arising from Bohmian mechanics, which is what emerges from Schrodinger's equation for a system of particles when we merely insist that "particles" means particles.
1 The measurement theory of Everett and de Broglie's pilot wav..
citeseer.ist.psu.edu /40656.html   (842 words)

  
 Multics Bibliography
An array of measuring tools devised to aid in the implementation of a prototype computer utility is discussed.
Measurements of the MULTICS three-level memory system are presented as examples of improving multi-level memory performance through drum folding.
It is shown that a shortest access time first queue discipline is the most efficient, with the access time being defined as the time required for the drum to be positioned, and is measured from the finish of service of the last request to the beginning of the data transfer for the present request.
www.multicians.org /biblio.html   (11750 words)

  
 Optical Bell-state analysis in the coincidence basis
Most optical Bell-state measurements utilize two-photon interference at a beam splitter.
By creating polarization-entangled photons with spontaneous parametric down-conversion using a first-order Hermite-Gaussian pump beam, we invert the usual interference behavior and perform an incomplete Bell-state measurement in the coincidence basis.
We discuss the possibility of a complete Bell-state measurement in the coincidence basis using hyperentangled states (Phys.
www.edpsciences.org /articles/epl/abs/2003/08/7575/7575.html   (119 words)

  
 InternetWeek   (Site not responding. Last check: 2007-10-04)
It's easy to overlook the importance of a company's IT infrastructure in constructing an e-learning measurement program, yet the precision and quality of measurement is only as good as the quality of the data being measured.
The challenge was to isolate training's impact on increased sales from other outside influences that could have affected increased sales--a marketing program, for instance, or government's habit of spending all its budget before the end of the fiscal year.
Toni Hodges, manager of measurement and evaluation, looked at sales before and after training and compared the average of post-training sales to a trend analysis that suggested the direction sales were headed without any training.
www.internetweek.com /indepth/indepth110600-1.htm   (539 words)

  
 Newswise
Researchers from the Commerce Department's National Institute of Standards and Technology and Bell Laboratories of Lucent Technologies have teamed to produce a more precise method for measuring the frequency of visible and infrared light (Science, 4-28-00).
The measurements made by the NIST/Lucent system have a higher level of precision than conventionally derived ones because they are directly compared to the well-defined primary frequency standard of a cesium-133 atomic clock.
This makes it possible to determine the absolute frequency of each of the "teeth" of the comb, and provides a means of measuring optical frequencies with a single laser.
www.newswise.com /articles/view?id=MEASURE.BEL   (579 words)

  
 Yanhua Shih, UMBC Physics   (Site not responding. Last check: 2007-10-04)
Foundations of quantum mechanics: measurement theory, the uncertainty principle, and in particular, the understanding of the nature of photon.
Bell State Preparation Using Pulsed Non-degenerate Two-photon Entanglement, QELS2001, Baltimore, (2001) (Y.-H. Kim, S.P. Kulik, and Y.H. Shih).
"Measurement Absolute Radiance in the Infrared using Correlated Visible Photons", Technical Digest of CLEO'97, Baltimore, (1997) (A. Migdall, R. Datla, A.V. Sergienko, and Y.H. Shih).
physics2.umbc.edu /Documents/Faculty/shih.html   (4193 words)

  
 research.html   (Site not responding. Last check: 2007-10-04)
We show theoretically that Bell-type correlations can be observed between continuous variable measurements performed on a parametric source.
An auxiliary measurement, performed on the detection environment, negates the possibility of constructing a local realistic description of these correlations.
Here we describe how entangled atoms can violate Bell's inequality, and how these violations can be measured with a very high detection efficiency.
www.physics.uq.edu.au /people/billm/research.html   (164 words)

  
 papers.html
W.J. Munro, ``Discrete Phase Measurements and the Bell inequality'',J. Opt.
Munro and G. Milburn, `'Phase Measurement Tests of Quantum Mechanics in Nondegenerate Parametric Oscillation'', accepted to PRA (1999).
Ralph, W. Munro and R. Polkinghorne, ``Proposal for the Measurement of Bell-type Correlations from Continuous Variables'', accepted to Phys.
www.physics.uq.edu.au /people/billm/publications.html   (589 words)

  
 Photographic Filters, Light Conversions, and More!   (Site not responding. Last check: 2007-10-04)
Using Filters for Non-Traditional Light Sources such as fluorescent, sodium vapor, metal halide, mercury, and clear mercury lamps with Eastman Kodak Films.
Color Temperature & Light Source measured in both Kelvin and MIRED shift values for white-flame carbon arc, daylight, skylight, overcast, and certain types of tungsten lamps.
Light Measurement Conversions for converting a given ISO/Shutter Speed/f-stop into LUX, EV, Candelas per square foot (cd/sq ft), Footcandles and Footlambert values.
www.geocities.com /thombell   (742 words)

  
 Emerging Auditing Technologies   (Site not responding. Last check: 2007-10-04)
This course focuses on the assurances given to financial statements and other documents by the independent auditor in the context of auditing organizations and their business strategies.
The BM process and risk measurement, and application to cases: what level., type, and strength of assurance an audit provides and compare this to other kinds of assurance?
The holistic approach to audit and business risk measurement from Bell et al.
www.huizenga.nova.edu /syllabi/masters/macc/gmp5715.cfm   (1710 words)

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