Question on Entanglement

[KtownChemist]

To my understanding Quantum Entanglement is when a single photon is split into two identical photons where a change in one photon produces an exact change in the other photon.

 

Now, my question is that when the photon is split, one part travels horizontally on the earth while the other travels straight up into the sky. Will the particle moving horizontally redshift the same as the particle moving upward?

[Klaynos]

You're understanding if wrong.

 

Entanglement is when two particles (they can be photons) are created in such a way as some property is entangled, say their polarisation state. Take particles A and B, after creating it has a polarisation state which is a superpositon of both state s and p, it is known that if particle A has state s then B must have state p.

 

Both of these two points are important.

 

Currently either particle is in BOTH states.

 

We measure the state of particle A and find it is in state s, we instantly know that particle B is in state p, no matter how far way it is.

[KtownChemist]

Take particles A and B, after creating it has a polarisation state which is a superpositon of both state s and p, it is known that if particle A has state s then B must have state p.

 

Both of these two points are important.

 

Currently either particle is in BOTH states.

 

We measure the state of particle A and find it is in state s, we instantly know that particle B is in state p, no matter how far way it is.

Thanks for your explanation, This seems logical and true, but now the question arises that if if particle A is in state s and particle B is in state p, If you add or take away energy from particle A will particle B continue to be entangled or will it suddenly sever its ties and become free? How do you untangle a particle

[proton]

Entanglement is when two particles (they can be photons) are created in such a way as some property is entangled, say their polarisation state.

For example: Let two electrons be moving head on where one electron has spin up and the other electron has spin down. After they collide it will be impossible, if not meaningless, to determine/say which electron was which. The total angular momentum must be conserved. That means that whatever spin is measured on one of them the other must have the exact opposite.

Currently either particle is in BOTH states.

Ouch!! Personally I'd never put it in those words. I'd phrase it as the system is in a superposition of two eigenstates.

[Klaynos]

Thanks for your explanation, This seems logical and true, but now the question arises that if if particle A is in state s and particle B is in state p, If you add or take away energy from particle A will particle B continue to be entangled or will it suddenly sever its ties and become free? How do you untangle a particle

 

Once you conduct the measurement you break the entanglement.

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Ouch!! Personally I'd never put it in those words. I'd phrase it as the system is in a superposition of two eigenstates.

 

I'd normally agree with you, but then I'd have to explain what that means.

[proton]

I'd normally agree with you, but then I'd have to explain what that means.

Quite true!

[swansont]

Once you conduct the measurement you break the entanglement.

 

If the measurement is of the parameter that is entangled. A different measurement need not break the entanglement.

[emcelhannon]

What is the nature of the observations affect on the entanglment. Could there ever be a way to observe without interfering, or is it an absolute rule. If it's absolute, how was it determined. ie examples of experiments

[Bishadi]

What is the nature of the observations affect on the entanglment. Could there ever be a way to observe without interfering, or is it an absolute rule. If it's absolute, how was it determined. ie examples of experiments

 

 

 

this subject is the bomb folks!

 

sure bell labs has described entanglement but the easiest method of observing entanglement is by human experience.

 

 

Words entangle mass! Ie... you read what i am conveying, you measure, weigh and log the interaction. But nothing exchanged except the photon and appicability in association to the previously recorded definitions to the words. When the correct alignment find coherance, you understand what is conveyed and an action can ensue (potential to mass).

 

Em (light/photon/electromagnetic energy) shared between mass entangles all exposed to that dimension (slice) in time. (ieee... words can transcend time; see books)

 

Now the longer bodies exchange energy a greater potential can ensue between the bodies (see casimir, van der waals)

 

at bell labs, Mit and all over the world; this single property of energy is finally being measured and will be proven that this property is the 'missing link' to physics

 

ie.... show me entanglement in virial theorem before the 'creation' of the entities dark energy/matter?

 

let the claim stand; entangled energy between mass is that gravity between mass (just note what E=mc2 means; that mass is just em)

[swansont]

What is the nature of the observations affect on the entanglment. Could there ever be a way to observe without interfering, or is it an absolute rule. If it's absolute, how was it determined. ie examples of experiments

 

If you measure the entangled attribute, you destroy the entanglement — the wave function collapses.

[Bishadi]

there is more:

 

Entangled images from 4-wave mixing in rubidium vapor

Marino, A.M.; Boyer, V.; Pooser, R.C.; Lett, P.D.

 

Lasers and Electro-Optics, 2008 and 2008 Conference on Quantum Electronics and Laser Science. CLEO/QELS 2008. Conference on

Volume , Issue , 4-9 May 2008 Page(s):1 - 2

Digital Object Identifier

 

 

Summary:We show that non-degenerate 4-wave mixing in an atomic vapor can produce highly multimode twin beams. The process can be used to generate arbitrarily-shaped continuous-variable entangled twin beams that contain quantum-correlations in time and space.

 

and http://www.jqi.umd.edu/news/80-entangled-images-and-delayed-epr-entanglement.html

 

note in BEC the coherance can be maintained

 

Cool atoms make physics prize matter

 

Philip Ball

 

Wolfgang Ketterle of the Massachusetts Institute of Technology (MIT) and Carl Wieman and Eric Cornell of JILA, an interdisciplinary research centre in Boulder, Colorado, have won this year's Nobel Prize in Physics for their work in making and understanding Bose–Einstein condensates (BECs).This new form of matter, a strange state in which a group of atoms behaves as a single particle, was first created in 1995 by Wieman and Cornell by cooling atoms of rubidium to within less than a millionth of a degree of absolute zero

 

 

coupled with

 

Quantum physicist Christopher Foot, at the University of Oxford in the U.K., also presented his work on cold atoms at the July meeting in Barcelona. He explains that this strangeness doesn't stop with atoms overlapping – atoms at temperatures close to absolute zero also become 'entangled' too.

 

Spooky actions

 

"Small particles such as atoms and electrons behave in strange ways that often seem very weird when compared to our everyday experience of large 'ordinary' objects such as a tennis ball or football," he says.

 

"A single quantum object can exist in two places at once, but this is not really as strange as it first appears when considered in terms of waves. However, there is a second property of quantum systems of two or more particles that is truly difficult to understand," says Foot. "Indeed Einstein pointed out a consequence of [entanglement] which is so bizarre that he thought there must be something wrong."

 

Atoms possess certain properties, such as their weight, charge, and the direction of spin of their electrons. At close to absolute zero, though, the direction of spin is like the Duke of York's men: neither up nor down. "It is in a state of indecision," says Foot.

 

A pair of atoms in this undecided state has what Einstein called a "spooky" influence on each other, even at a distance. These entangled atoms can communicate to their partners without the information following any path as we traditionally understand it. It's as if the information is teleported from one atom to another.

 

"By understanding [entanglement] we can do new things such as build quantum computers that, in the future, could store and process far more information than ordinary computers and may outperform them in certain applications, e.g. cracking the encryption commonly used to transmit information

electronically," says Foot.

 

just leaving the doors ajar

[Klaynos]

Do you have teh DOI for your first reference?

[Bishadi]

Do you have teh DOI for your first reference?

 

http://lanl.arxiv.org/find/all/1/all:+pooser/0/1/0/all/0/1

 

 

here is tool

 

see 3rd item

 

hit pdf and review the whole pub if you like

 

enjoy

 

 

p/s..........notice all the work on the subject; its the hot one on the globe!

[Klaynos]

http://lanl.arxiv.org/find/all/1/all:+pooser/0/1/0/all/0/1

 

 

here is tool

 

see 3rd item

 

hit pdf and review the whole pub if you like

 

enjoy

 

 

p/s..........notice all the work on the subject; its the hot one on the globe!

 

Thanks.

[emcelhannon]

If you measure the entangled attribute, you destroy the entanglement — the wave function collapses.

 

Thank you,

If you're able to collapse the wave function of an entangled particle at a distance, what keeps us from being able to input a code into the process and communicate at a distance via a series of entangled particles shot from between. I know it's impossible, but I'd appreciate a clearer explaination then I've been able to find elsewhere.

[swansont]

Thank you,

If you're able to collapse the wave function of an entangled particle at a distance, what keeps us from being able to input a code into the process and communicate at a distance via a series of entangled particles shot from between. I know it's impossible, but I'd appreciate a clearer explaination then I've been able to find elsewhere.

 

You don't know what state the particle will collapse into. There's no information transfer in simply measuring state A or B.

[emcelhannon]

And I guess it's impossible to simply tell if the others wave function has collapsed, or not, without causing it to collapse. All observations would be of particles, not waves?

[swansont]

And I guess it's impossible to simply tell if the others wave function has collapsed, or not, without causing it to collapse. All observations would be of particles, not waves?

 

You know it has collapsed if you made the measurement — I don't think there's any way to tell if the particle was in a superposition beforehand or not. But it wouldn't do you any good for FTL communication anyway, because you don't know what state the particle would be in.

 

You could measure polarization, which is a wave measurement.

[emcelhannon]

Regarding "But it wouldn't do you any good for FTL communication anyway, because you don't know what state the particle would be in."

 

 

If you could tell if it were in a superposition beforehand, you would recieve information regarding the behavior of the opposite scientist, (wether they took a measurment or not).

I feel like I'm missing something. Thank you for your patience.

[swansont]

If the other scientist had not yet made a measurement, allowing the particle to still be in a superposition, they would have to communicate this to you somehow. Which would require normal communication speed.

[emcelhannon]

I think I see, but to be sure -

 

[*]We can never actually observe a particle in a supperposition.

[*]Supperposition particles and particles which have committed to its state, (because their correlated partner has been measured) are indistinguishable when they enter our measurments.

Correct me.

[swansont]

Right.

[emcelhannon]

Swansot,

You were very helpful.

Thanks

[emcelhannon]

Alright Swansont,

I've done some reading, per the advice of some moderators, on Wikipedia. What I read here seems contradictory, but I suspect that I'm assuming something that should not be assumed.

In the Schrodinger's Cat article, under Practical applications it reads, "It is possible to send light that is in a superposition of states down a fiber optic cable. Placing a wiretap in the middle of the cable that intercepts and retransmits the transmission will collapse the wave function (in the Copenhagen interpretation, "perform an observation") and cause the light to fall into one state or another. By performing statistical tests on the light received at the other end of the cable, one can tell whether it remains in the superposition of states or has already been observed and retransmitted. In principle, this allows the development of communication systems that cannot be tapped without the tap being noticed at the other end.... This experiment can be argued to illustrate that "observation" in the Copenhagen interpretation has nothing to do with consciousness (unless some version of panpsychism is true), in that a perfectly unconscious wiretap will cause the statistics at the end of the wire to be different. Such a test would only work if the collapse occurs after (as opposed to before) observation; otherwise, it would appear collapsed whether it had been wiretapped or not."

 

Is this article stating that we can tell if a collapse has or has not occurred prior to our measurement?

[swansont]

That's because you've changed the conditions — you're looking at a different experiment.

 

The reason an eavesdropper can be detected is that they will not know what measurement to make; in this case, the polarization axis to use for the detection. That's not true in the previous example, where there were just the two scientists, who had already agreed on the measurement basis.