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The EPR article highlighted the strange nature of quantum entanglement, which is a characteristic of a quantum state that is a combination of the states of two systems ( for example, two subatomic particles ), that once interacted but were then separated and are not each in a definite state.
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EPR and article
At the time the EPR article was written, it was known from experiments that the outcome of an experiment sometimes cannot be uniquely predicted.
Schrödinger intended his thought experiment as a discussion of the EPR article — named after its authors Einstein, Podolsky, and Rosen — in 1935.
Schrödinger and Einstein exchanged letters about Einstein's EPR article, in the course of which Einstein pointed out that the state of an unstable keg of gunpowder will, after a while, contain a superposition of both exploded and unexploded states.
EPR and quantum
In many-worlds, the subjective appearance of wavefunction collapse is explained by the mechanism of quantum decoherence, which resolves all of the correlation paradoxes of quantum theory, such as the EPR paradox and Schrödinger's cat, since every possible outcome of every event defines or exists in its own " history " or " world ".
Albert Einstein and his colleagues Boris Podolsky and Nathan Rosen ( known collectively as EPR ) designed a thought experiment intended to reveal what they believed to be inadequacies of quantum mechanics.
The original EPR paradox challenges the prediction of quantum mechanics that it is impossible to know both the position and the momentum of a quantum particle.
However, quantum field theories that are " local " in this sense appear to violate the principle of locality as defined by EPR, but they nevertheless do not violate locality in a more general sense.
Therefore, as outlined in the example above, neither the EPR experiment nor any quantum experiment demonstrates that faster-than-light signaling is possible.
The one suggested by EPR is that quantum mechanics, despite its success in a wide variety of experimental scenarios, is actually an incomplete theory.
In 1964, John Bell showed that the predictions of quantum mechanics in the EPR thought experiment are significantly different from the predictions of a particular class of hidden variable theories ( the local hidden variable theories ).
In the EPR paper ( 1935 ) the authors realised that quantum mechanics was inconsistent with their assumptions, but Einstein nevertheless thought that quantum mechanics might simply be augmented by hidden variables ( i. e. variables which were, at that point, still obscure to him ), without any other change, to achieve an acceptable theory.
Most physicists today believe that quantum mechanics is correct, and that the EPR paradox is a " paradox " only because classical intuitions do not correspond to physical reality.
How EPR is interpreted regarding locality depends on the interpretation of quantum mechanics one uses.
The EPR paradox has deepened our understanding of quantum mechanics by exposing the fundamentally non-classical characteristics of the measurement process.
Such explanations, which are still encountered in popular expositions of quantum mechanics, are debunked by the EPR paradox, which shows that a " measurement " can be performed on a particle without disturbing it directly, by performing a measurement on a distant entangled particle.
John Bell showed that this " EPR " paradox led to experimentally testable differences between quantum mechanics and local realistic theories.
The prerequisites for quantum teleportation are a qubit that is to be teleported, a conventional communication channel capable of transmitting two classical bits ( i. e., one of four states ), and means of generating an entangled EPR pair of qubits, performing a Bell measurement on the EPR pair, and manipulating the quantum state of one of the pair.
At location A, a Bell measurement of the EPR pair qubit and the qubit to be teleported ( for example, quantum state of a photon ) is performed, yielding two classical bits of information.
At location B, the EPR pair qubit is modified ( if necessary ), using the two bits to select the correct one of four possible quantum states.
Research into quantum entanglement was initiated by a 1935 paper by Albert Einstein, Boris Podolsky, and Nathan Rosen describing the EPR paradox and several papers by Erwin Schrödinger shortly thereafter.
EPR and entanglement
Following the EPR paper, Erwin Schrödinger wrote a letter ( in German ) to Einstein in which he used the word Verschränkung ( translated by himself as entanglement ) " to describe the correlations between two particles that interact and then separate, as in the EPR experiment ".
One of these is the phenomenon of entanglement, as illustrated in the EPR paradox, which seemingly violates principles of local causality.
The singlet state formed from a pair of electrons has many peculiar properties, and plays a fundamental role in the EPR paradox and quantum entanglement.
In the case of the EPR paradox, quantum entanglement appears to allow for the physical impossibility of information transmitted faster than the speed of light, violating special relativity.
EPR and which
The EPR authors preferred the second explanation according to which that information was encoded in some ' hidden parameters '.
The current usage of realism and completeness originated in the 1935 paper in which Einstein and others proposed the EPR paradox.
Following the argument in the Einstein – Podolsky – Rosen ( EPR ) paradox paper ( but using the example of spin, as in David Bohm's version of the EPR argument ), Bell considered an experiment in which there are " a pair of spin one-half particles formed somehow in the singlet spin state and moving freely in opposite directions.
The crash was due to an anti-icing system being left off, which caused an inaccurately high engine pressure ratio ( EPR ) indication at an extremely low power setting, and the crew's failure to either abort the takeoff or apply maximum engine power.
This failure of the classical view was one of the conclusions of the EPR thought experiment in which two remotely located observers, now commonly referred to as Alice and Bob, perform independent measurements of spin on a pair of electrons, prepared at a source in a special state called a spin singlet state.
In 2006 Abraham was appointed Non-Executive Chairman of the Board of AREVA Inc., the American arm of the French nuclear company Areva, which is planning to build EPR nuclear power plants in the United States, and is building the mixed oxide fuel ( MOX ) manufacturing plant at the Savannah River Site to convert legacy weapons-grade plutonium into power station fuel.
Naturally occurring praseodymium is composed of one stable isotope, praseodymium-141, which is of use in NMR and EPR spectroscopy.
The Dutch Ministry of Health is working on a virtual national Electronic Patient Records ( EPR ) which will enable healthcare providers to share patient data.
The EFG couples with the nuclear electric quadrupole moment of quadrupolar nuclei ( those with spin quantum number greater than one-half ) to generate an effect which can be measured using several spectroscopic methods, such as nuclear magnetic resonance ( NMR ), electron paramagnetic resonance ( EPR, ESR ), nuclear quadrupole resonance ( NQR ), Mössbauer spectroscopy or perturbed angular correlation ( PAC ).
This thought experiment, which came to be known as the EPR paradox, hinges on the principle of locality.
In September 2008 it was announced, by Electricité de France ( EDF ), that a third, twin-unit European Pressurized Reactor ( EPR ) reactor known as Hinkley Point C is planned, to replace Hinkley Point B which is due for closure in 2016.
As a result, EPR is generally applied to post-consumer wastes which place increasing physical and financial demands on municipal waste management.
An EPR pair is a pair of qubits which jointly are in a Bell state, that is, entangled with each other.
The leaders in national experience with PWRs, offering reactors for export, are the United States ( which offers the passively-safe AP1000, a Westinghouse design, as well as several smaller, modular, passively-safe PWRs, such as the Babcock and Wilcox MPower, and the NuScale MASLWR ), the Russian Federation ( offering both the VVER-1000 and the VVER-1200 for export ), the Republic of France ( offering the AREVA EPR for export ), and Japan ( offering the Mitsubishi Advanced Pressurized Water Reactor for export ); in addition, both the People's Republic of China and the Republic of Korea are both noted to be rapidly ascending into the front rank of PWR-constructing nations as well, with the Chinese being engaged in a massive program of nuclear power expansion, and the Koreans currently designing and constructing their second generation of indigenous designs.
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