# Thread: Monkeys do not include 'entanglement' in the physics descriptions, why?

1. ## Physicists do not include 'entanglement' in their physics descriptions, why?

Quantum Entanglement and Information

First published Mon Aug 13, 2001; substantive revision Thu Aug 26, 2010

Quantum entanglement is a physical resource, like energy, associated with the peculiar nonclassical correlations that are possible between separated quantum systems. Entanglement can be measured, transformed, and purified. A pair of quantum systems in an entangled state can be used as a quantum information channel to perform computational and cryptographic tasks that are impossible for classical systems. The general study of the information-processing capabilities of quantum systems is the subject of quantum information theory.
•1. Quantum Entanglement
•2. Exploiting Entanglement: Quantum Teleportation
•3. Quantum Information
•4. Quantum Cryptography
•5. Quantum Computation
•6. Interpretative Remarks
•Bibliography
•Other Internet Resources
•Related Entries

--------------------------------------------------------------------------------

1. Quantum Entanglement

In 1935 and 1936, Schrödinger published a two-part article in the Proceedings of the Cambridge Philosophical Society in which he discussed and extended a remarkable argument by Einstein, Podolsky, and Rosen. The Einstein-Podolsky-Rosen (EPR) argument was, in many ways, the culmination of Einstein's critique of the orthodox Copenhagen interpretation of quantum mechanics, and was designed to show that the theory is incomplete. (See The Einstein-Podolsky-Rosen Argument in Quantum Theory and Copenhagen Interpretation of Quantum Mechanics.) In classical mechanics the state of a system is essentially a list of the system's properties — more precisely, it is the specification of a set of parameters from which the list of properties can be reconstructed: the positions and momenta of all the particles comprising the system (or similar parameters in the case of fields). The dynamics of the theory specifies how properties change in terms of a law of evolution for the state. Pauli characterized this mode of description of physical systems as a ‘detached observer’ idealization. See Pauli's letter to Born in The Born-Einstein Letters (Born, 1992; p. 21. On the Copenhagen interpretation, such a description is not possible for quantum systems. Instead, the quantum state of a system should be understood as a catalogue of what an observer has done to the system and what has been observed, and the import of the state then lies in the probabilities that can be inferred (in terms of the theory) for the outcomes of possible future observations on the system. Einstein rejected this view and proposed a series of arguments to show that the quantum state is simply an incomplete characterization of the system. The missing parameters are sometimes referred to as ‘hidden parameters’ or ‘hidden variables’ (although Einstein did not use this terminology, presumably because he did not want to endorse any particular ‘hidden variable’ theory).

It should not be supposed that Einstein's definition of a complete theory included the requirement that it be deterministic. Rather, he required certain conditions of separability and locality for composite systems consisting of separated component systems: each component system separately should be characterized by its own properties (even if these properties manifest themselves stochastically), and it should be impossible to alter the properties of a distant system instantaneously (or the probabilities of these properties) by acting on a local system. In later analyses — notably in Bell's extension of the EPR argument — it became apparent that these conditions, suitably formulated as probability constraints, are equivalent to the requirement that statistical correlations between separated systems should be reducible to probability distributions over common causes (deterministic or stochastic) in the sense of Reichenbach. (See Bell's Theorem and Reichenbach's Common Cause Principle.)

In the original EPR article, two particles are prepared from a source in a certain quantum state and then move apart. There are ‘matching’ correlations between both the positions of the two particles and their momenta: a measurement of either position or momentum on a particular particle will allow the prediction, with certainty, of the outcome of a position measurement or momentum measurement, respectively, on the other particle. These measurements are mutually exclusive: either a position measurement can be performed, or a momentum measurement, but not both simultaneously. Either correlation can be observed, but the subsequent measurement of momentum, say, after establishing a position correlation, will no longer yield any correlation in the momenta of the two particles. It is as if the position measurement disturbs the correlation between the momentum values. The puzzle is that the assumption of the completeness of the quantum state of the particle pair is inconsistent with the assignment of labels to the particles separately that could be associated with appropriately correlated values for the outcomes of position and momentum measurements. These labels would be the common causes of the correlations, and would provide an explanation of the correlations in terms of the initial correlations between the properties of the two systems at their source. EPR concluded that the quantum state was incomplete.

Here is how Schrödinger put the puzzle in the first part of his two-part article (Schrödinger, 1935; p. 559):

Yet since I can predict either x1 or p1 without interfering with the system No. 1 and since system No. 1, like a scholar in an examination, cannot possibly know which of the two questions I am going to ask first: it so seems that our scholar is prepared to give the right answer to the first question he is asked, anyhow. Therefore he must know both answers; which is an amazing knowledge; quite irrespective of the fact that after having given his first answer our scholar is invariably so disconcerted or tired out, that all the following answers are ‘wrong.’

What Schrödinger showed was that if two particles are prepared in a quantum state such that there is a matching correlation between two ‘canonically conjugate’ dynamical quantities — quantities like position and momentum whose values suffice to specify all the properties of a classical system — then there are infinitely many dynamical quantities of the two particles for which there exist similar matching correlations: every function of the canonically conjugate pair of the first particle matches with the same function of the canonically conjugate pair of the second particle. Thus (Schrödinger, p. 559) system No. 1 ‘does not only know these two answers but a vast number of others, and that with no mnemotechnical help whatsoever, at least with none that we know of.’

Schrödinger coined the term ‘entanglement’ to describe this peculiar connection between quantum systems (Schrödinger, 1935; p. 555):

http://plato.stanford.edu/entries/qt-entangle/

why is it not in the Big Bang physics?

Nor in particle physics (cern/higgs pursuit)?

String?

How is it that a property does exist in nature and physicist dont use it, WHY?
Last edited by Bishadi; Aug 02 2012 at 05:20 AM. Reason: title correction

2. Originally Posted by Bishadi
Quantum Entanglement and Information

First published Mon Aug 13, 2001; substantive revision Thu Aug 26, 2010

Quantum entanglement is a physical resource, like energy, associated with the peculiar nonclassical correlations that are possible between separated quantum systems. Entanglement can be measured, transformed, and purified. A pair of quantum systems in an entangled state can be used as a quantum information channel to perform computational and cryptographic tasks that are impossible for classical systems. The general study of the information-processing capabilities of quantum systems is the subject of quantum information theory.
•1. Quantum Entanglement
•2. Exploiting Entanglement: Quantum Teleportation
•3. Quantum Information
•4. Quantum Cryptography
•5. Quantum Computation
•6. Interpretative Remarks
•Bibliography
•Other Internet Resources
•Related Entries

--------------------------------------------------------------------------------

1. Quantum Entanglement

In 1935 and 1936, Schrödinger published a two-part article in the Proceedings of the Cambridge Philosophical Society in which he discussed and extended a remarkable argument by Einstein, Podolsky, and Rosen. The Einstein-Podolsky-Rosen (EPR) argument was, in many ways, the culmination of Einstein's critique of the orthodox Copenhagen interpretation of quantum mechanics, and was designed to show that the theory is incomplete. (See The Einstein-Podolsky-Rosen Argument in Quantum Theory and Copenhagen Interpretation of Quantum Mechanics.) In classical mechanics the state of a system is essentially a list of the system's properties — more precisely, it is the specification of a set of parameters from which the list of properties can be reconstructed: the positions and momenta of all the particles comprising the system (or similar parameters in the case of fields). The dynamics of the theory specifies how properties change in terms of a law of evolution for the state. Pauli characterized this mode of description of physical systems as a ‘detached observer’ idealization. See Pauli's letter to Born in The Born-Einstein Letters (Born, 1992; p. 21. On the Copenhagen interpretation, such a description is not possible for quantum systems. Instead, the quantum state of a system should be understood as a catalogue of what an observer has done to the system and what has been observed, and the import of the state then lies in the probabilities that can be inferred (in terms of the theory) for the outcomes of possible future observations on the system. Einstein rejected this view and proposed a series of arguments to show that the quantum state is simply an incomplete characterization of the system. The missing parameters are sometimes referred to as ‘hidden parameters’ or ‘hidden variables’ (although Einstein did not use this terminology, presumably because he did not want to endorse any particular ‘hidden variable’ theory).

It should not be supposed that Einstein's definition of a complete theory included the requirement that it be deterministic. Rather, he required certain conditions of separability and locality for composite systems consisting of separated component systems: each component system separately should be characterized by its own properties (even if these properties manifest themselves stochastically), and it should be impossible to alter the properties of a distant system instantaneously (or the probabilities of these properties) by acting on a local system. In later analyses — notably in Bell's extension of the EPR argument — it became apparent that these conditions, suitably formulated as probability constraints, are equivalent to the requirement that statistical correlations between separated systems should be reducible to probability distributions over common causes (deterministic or stochastic) in the sense of Reichenbach. (See Bell's Theorem and Reichenbach's Common Cause Principle.)

In the original EPR article, two particles are prepared from a source in a certain quantum state and then move apart. There are ‘matching’ correlations between both the positions of the two particles and their momenta: a measurement of either position or momentum on a particular particle will allow the prediction, with certainty, of the outcome of a position measurement or momentum measurement, respectively, on the other particle. These measurements are mutually exclusive: either a position measurement can be performed, or a momentum measurement, but not both simultaneously. Either correlation can be observed, but the subsequent measurement of momentum, say, after establishing a position correlation, will no longer yield any correlation in the momenta of the two particles. It is as if the position measurement disturbs the correlation between the momentum values. The puzzle is that the assumption of the completeness of the quantum state of the particle pair is inconsistent with the assignment of labels to the particles separately that could be associated with appropriately correlated values for the outcomes of position and momentum measurements. These labels would be the common causes of the correlations, and would provide an explanation of the correlations in terms of the initial correlations between the properties of the two systems at their source. EPR concluded that the quantum state was incomplete.

Here is how Schrödinger put the puzzle in the first part of his two-part article (Schrödinger, 1935; p. 559):

Yet since I can predict either x1 or p1 without interfering with the system No. 1 and since system No. 1, like a scholar in an examination, cannot possibly know which of the two questions I am going to ask first: it so seems that our scholar is prepared to give the right answer to the first question he is asked, anyhow. Therefore he must know both answers; which is an amazing knowledge; quite irrespective of the fact that after having given his first answer our scholar is invariably so disconcerted or tired out, that all the following answers are ‘wrong.’

What Schrödinger showed was that if two particles are prepared in a quantum state such that there is a matching correlation between two ‘canonically conjugate’ dynamical quantities — quantities like position and momentum whose values suffice to specify all the properties of a classical system — then there are infinitely many dynamical quantities of the two particles for which there exist similar matching correlations: every function of the canonically conjugate pair of the first particle matches with the same function of the canonically conjugate pair of the second particle. Thus (Schrödinger, p. 559) system No. 1 ‘does not only know these two answers but a vast number of others, and that with no mnemotechnical help whatsoever, at least with none that we know of.’

Schrödinger coined the term ‘entanglement’ to describe this peculiar connection between quantum systems (Schrödinger, 1935; p. 555):

http://plato.stanford.edu/entries/qt-entangle/

why is it not in the Big Bang physics?

Nor in particle physics (cern/higgs pursuit)?

String?

How is it that a property does exist in nature and physicist dont use it, WHY?
The dynamics of the theory specifies how properties change in terms of a law of evolution for the state

The "Law of Evolution"?

huh?

3. You cannot use entanglement to send information without a classical channel of information, end of story.

4. Originally Posted by taikoo
The dynamics of the theory specifies how properties change in terms of a law of evolution for the state

The "Law of Evolution"?

huh?
an evolution is a progression of state, versus the reduction. kind of like adding 2 colors, red and yellow and getting orange.

5. Originally Posted by Anarcho-Technocrat
You cannot use entanglement to send information without a classical channel of information, end of story.
not concerned with your claim.

Entanglement is a 'potential' that needs to be included in large body predictions along with the molecular, thru to chemical. Are you up for the fun?

nothing pseudo about entanglement and it is that very property that makes the EPR comprehensible.

the problem is, one group is lost on just playing with the theorem, versus putting the skills to measured evidence. like entanglement, for example.

It is a NATURAL property, that has not been included in what you call 'physics'.

Sorry to burst your bubble.

ps...You personally cannot ask me for assistence. you've lost my respect in just about anything!

6. these guys are using it

PDF]
calculation of quantum entanglement using a genetic algorithm

soar.wichita.edu/dspace/bitstream/handle/10057/1144/t07027.pdf?...

File Format: PDF/Adobe Acrobat
by J Lesniak - 2007 - Related articles
As systems that use entanglement have evolved, the calculation of entanglement has ... A general method was developed for the calculation of entanglement for ...

Can the concurrence be calculated in terms of the entanglement of ...

physics.stackexchange.com/.../can-the-concurrence-be-calculated-in-t...

Feb 14, 2012 – If I somehow know the entanglement of formation, $E_F$ for two mixed qubits, where. E_F = -x \log x - (1-x) \log (1-x), ...

An efficient numerical method for calculating the entanglement of ...

arxiv.org › quant-ph

by JR Gittings - 2003 - Cited by 5 - Related articles
Feb 3, 2003 – Abstract: We present a conjugate gradient method for calculating the entanglement of formation of arbitrary mixed quantum states of any ...

[PDF]
Entanglement and electron correlation in quantum chemistry ...

www.chem.purdue.edu/kais/paper/Huang-53.pdf

File Format: PDF/Adobe Acrobat - Quick View
by Z HUANG - Cited by 4 - Related articles
Ab initio configuration interaction calculation for entanglement is presented for .... calculating entanglement for a simpler two-spin model system. This is a model ...

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Entanglement as measure of electron–electron correlation in ...

www.chem.purdue.edu/kais/paper/ref94.pdf

File Format: PDF/Adobe Acrobat - Quick View
by Z Huang - 2005 - Cited by 42 - Related articles
tum chemistry calculations. Entanglement is directly observable and it is one of the most striking properties of quantum mechanics. As an example we calculate ...

7. "Quantum entanglement is a strange and non-intuitive aspect of the quantum theory of matter, which has puzzled and intrigued physicists since the earliest days of the quantum theory," said Leon Balents, senior author of a recent paper on this topic published in the journal Nature Physics. Balents is a professor of physics and a permanent member of KITP.

Quantum entanglement represents the extent to which measurement of one part of a system affects the state of another; for example, measurement of one electron influences the state of another that may be far away, explained Balents

then in another

Aug. 6, 2012 — A fundamental characteristic of quantum physics is the fact that two or more particles can exhibit correlations stronger than classically allowed. This unique characteristic applies particularly to quantum entanglement: as soon as the quantum state of a particle is measured the state of its entangled partner changes accordingly, regardless of how far apart the two entangled particles might be