Properties of entanglement between particles

Dec 2019
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USA
What determines the formation of entanglement between two particles? Is it just a distance between two particles which have not yet conferred a state/spin?
I read online that different types of particles like photon and electron could become entangled. Is this true?
Can one particle be entangled to only one or two or more other particles?
Could entangled particles be unentangled?
What if one photon that undertook a state becomes absorbed and its energy converted. What will happen to its previously entangled counterpart, will it lose state and return to a wavefunction?
 
Last edited:
Sep 2019
54
5
Azores
What determines the formation of entanglement between two particles? Is it just a distance between two particles which have not yet conferred a state/spin?
I read online that different types of particles like photon and electron could become entangled. Is this true?
Can one particle be entangled to only one or two or more other particles?
Could entangled particles be unentangled?
What if one photon that undertook a state becomes absorbed and its energy converted. What will happen to its previously entangled counterpart, will it lose state and return to a wavefunction?
Normally entangled is achieved by splitting a photon into two.
Yes different types of particles can be entangled.
Multiple photons can be entangled.
Entanglement is very easy to break ie decohere.
The unabsorbed photon will decohere.

Here is a wiki Quantum entanglement - Wikipedia
 
Dec 2019
3
0
USA
Normally entangled is achieved by splitting a photon into two.
Yes different types of particles can be entangled.
Multiple photons can be entangled.
Entanglement is very easy to break ie decohere.
The unabsorbed photon will decohere.

Here is a wiki Quantum entanglement - Wikipedia
Thank you clarifying. I looked at the Wikipedia page but still unclear.
So splitting a photon is like taking a higher energy photon, with shorter wavelength, and splitting it into two photons of longer wavelength, where each newborn photon has half of the original photon energy. I get this. But since not only other particles but even different types of particles could be entangled, it cannot be all through splitting (e.g., cannot split an electron). So what action is causing entanglement in those other cases? Also, what is common between how entanglement is achieved between two different types of particles and how it is achieved by splitting a photon?
Does the fact that entangled particles take an opposite state of its counterpart have anything to do with balance in the universe, like matter and anti-matter need to be in balance? Saw somewhere online that the need to maintain balance in the universe compels entangled photons to take opposite states.
If an odd number of photons is entangled, how are opposite states distributed since their number is uneven?
Is decoherence same thing as wavefunction collapse? Can decohered particles be entangled too (i.e., converted back into coherence through entangling them)?
I also saw online that to maintain entanglement state the temperature needs to be near absolute 0. Is this because in non-near 0 temperature other particles are likely to bump into entangled particle, casing it to decohere and break entanglement? Or is it for another reason? Either way, how could entangled particles be tested hundreds of miles apart from each other, since its not really practical to transport one of the entangled particles at near 0 temperature hundreds of miles away?
 
Sep 2019
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Azores
Entanglement happens naturally in some things Bose Einstein condensates for instance [quant-ph/0110114] Natural Entanglement in Bose-Einstein Condensates

Only electron pairs can be entangled as far as I am aware How to entangle two electrons – and do it again and again electrons orbiting atoms are also entangled.

I stand to be corrected but entangled particles can be described by the same wave function, when they decohere they are described separately. Entanglement works much better at near absolute zero.

Entangled particles decohere because they are interfered with, ie by measured or being bumped into.

 
Jun 2016
1,369
695
England
My impression of entanglement (hopefully someone else will correct this if I am wrong please)
is that when two (or more) quantum particles are in very close physical proximity
their probability functions overlap to such a degree that they can no longer be properly described as separate entities,
they essentially become a single (composite) quantum entity.
If these quantum entities subsequently separate physically, they remain connected as a quantum system, even though they may be physically distant from each other.
Eventually their different time histories (interactions with other quantum entities) will cause their quantum entanglement to decohere.
 
Sep 2019
54
5
Azores
Another interesting theoretical aspect of entanglement, is that virtual particles appearing in space will be entangled to differing degrees. This entanglement MAY be responsible for an additional long range gravitational force according to Emergent gravity by theoretical physicist Eric Verlinde. This entanglent effect MAY explain away most of Dark matter required in the universe by GR.
 
Apr 2015
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359
Somerset, England
1) Normally entangled is achieved by splitting a photon into two.
2) Yes different types of particles can be entangled.
Multiple photons can be entangled.
Entanglement is very easy to break ie decohere.
The unabsorbed photon will decohere.
1) Photons (and electrons) are indivisible 'particles'.

2) This is at variance with your later statement

Only electron pairs can be entangled as far as I am aware

Entanglement is complicated by the fact that there can be degrees of entanglement.
Full entanglement is called maximal entanglement,
Partial entanglement results in various special states, for instance with photons the colour may be entangled for 3 photons, resulting in what is called the W state.
 
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Sep 2019
54
5
Azores
1) Photons (and electrons) are indivisible 'particles'.

2) This is at variance with your later statement




Entanglement is complicated by the fact that there can be degrees of entanglement.
Full entanglement is called maximal entanglement,
Partial entanglement results in various special states, for instance with photons the colour may be entangled for 3 photons, resulting in what is called the W state.
OOPS
1) I think I should have wrote beams are split in beam splitters producing entangled photons. The beam consisting of multiple photons.
2) I am not sure if you are disagreeing different types of particles can be entangled or not ? cooper pairs of electrons can be entangled photons can be entangled bose einstein condensates of rubidium are entangled are they not.
 
Apr 2015
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Somerset, England
2) I am not sure if you are disagreeing different types of particles can be entangled or not ? cooper pairs of electrons can be entangled photons can be entangled bose einstein condensates of rubidium are entangled are they not.
Well it seem to me that you first said

Yes different types of particles can be entangled.
Then you contradicted yourself

Only electron pairs can be entangled as far as I am aware
So I am suggesting you clarify your meaning.
 
Sep 2019
54
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Azores
I was referring to the OPS questions.
The OP asked if more than 2 electrons can be entangled. My understanding is they are entangled in pairs, not 3 or 4 just 2!
 
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