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PostPosted: Mon Jun 19, 2017 2:59 pm 
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This is beyond my level of quantumming but... shit.

China's supposed tech advances present a fairly solid threat to The World As We Know It and this is out there. The put a laser on a satellite that orbits at 480km, generate a couple of entangled particles and beam them to ground stations 1200km apart, breaking the previous record for successful entanglement distance by a factor of 10.

Insane, right?

https://en.wikipedia.org/wiki/Quantum_entanglement

Quote:
Quantum entanglement is a physical phenomenon that occurs when pairs or groups of particles are generated or interact in ways such that the quantum state of each particle cannot be described independently of the others, even when the particles are separated by a large distance—instead, a quantum state must be described for the system as a whole.


Ok...


Quote:
By launching a group of quantum-enabled satellites, China hopes to create a super secure network that uses an encryption technique based on the principles of a field known as quantum communication.

“In physics we are trying, and we have demonstrated some encryption techniques that rely on the law of physics rather than the mathematical complexity and we call this quantum key distribution,” professor Ping Koy Lam from the ANU’s Department of Quantum Science told news.com.au last year, before China launched its first quantum satellite.

“For that to work you need to send laser beams that carry certain information, quantum information, and then you need the senders and the receivers to get together to find a protocol to secure the communication.”

The reason it can’t be hacked is because the information carried in the quantum state of a particle cannot be measured or cloned without destroying the information itself.

“We can show that this kind of quantum encryption works in a city radius or at most between two nearby cities,” Prof Lam said.

However China believes the atmosphere in space will allow the photons to travel further without disruption because “in space there’s nothing to attenuate light.”

In the latest experiment, both stations which received the photons were in the mountains of Tibet, at a height that reduced the amount of air the fragile photons had to traverse.


Impressive... and scary.


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PostPosted: Mon Jun 19, 2017 3:08 pm 
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guy smiley wrote:






Quote:

ANU’s




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PostPosted: Mon Jun 19, 2017 3:11 pm 
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I read about using quantum entanglement for "unbreakable" security some time last year - really fascinating stuff but I struggle to fully understand the concepts behind it.

I miss 6roucho :(


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PostPosted: Mon Jun 19, 2017 3:12 pm 
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Be interesting to see if it works out. Some smart dudes out there.


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PostPosted: Mon Jun 19, 2017 3:16 pm 
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JM2K6 wrote:
I read about using quantum entanglement for "unbreakable" security some time last year - really fascinating stuff but I struggle to fully understand the concepts behind it.

I miss 6roucho :(

:thumbup:

Me too. His smarts and ability to explain them... awesome guy. Great fun on the piss, too.

I forgot to link to the article I read and now I've found a better source

New Scientist

Quote:
“It took us almost 14 years to manage this achievement,” says Jian-Wei Pan of the University of Science and Technology of China in Hefei.


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PostPosted: Mon Jun 19, 2017 3:19 pm 
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:thumbup:


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PostPosted: Mon Jun 19, 2017 3:35 pm 
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I'm not 6roucho (nor even close), but I'll have a go at explaining this.

Quantum entanglement creates a pair of particles that "know" exactly what the other is doing - even when they are separated (in this case by a very long distance). This knowledge exchange happens instantaneously (seemingly - certainly much, much more quickly than the speed of light) [but as information can't be transmitted by this mechanism, it doesn't break the rules around relativity and the speed of light which strictly apply to information transmission].

I think what this new announcement is about is using entangled particles as a way to detect if somebody without the appropriate "key" is trying to access the encrypted message. There is a process called decoherence where particles "lose" their quantum mechanical properties (opening the box and looking at the cat for example). This seems to be the way that the encrypted information is destroyed if an unauthorised person tries to read it.

The big deal is the sheer distance over which the particles are separated - an engineering masterpiece by the looks of it.

As to how that is all done - you will need to ask somebody with a nobel prize in physics.


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PostPosted: Mon Jun 19, 2017 3:37 pm 
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Very bloody impressive.

Or as they say here ho bloody impressive.


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PostPosted: Mon Jun 19, 2017 3:55 pm 
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guy smiley wrote:
This is beyond my level of quantumming but... shit.

China's supposed tech advances present a fairly solid threat to The World As We Know It and this is out there. The put a laser on a satellite that orbits at 480km, generate a couple of entangled particles and beam them to ground stations 1200km apart, breaking the previous record for successful entanglement distance by a factor of 10.

Insane, right?

https://en.wikipedia.org/wiki/Quantum_entanglement

Quote:
Quantum entanglement is a physical phenomenon that occurs when pairs or groups of particles are generated or interact in ways such that the quantum state of each particle cannot be described independently of the others, even when the particles are separated by a large distance—instead, a quantum state must be described for the system as a whole.



Might I stop it there? What about observation effect?


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PostPosted: Mon Jun 19, 2017 3:57 pm 
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A5D5E5 wrote:
I'm not 6roucho (nor even close), but I'll have a go at explaining this.

Quantum entanglement creates a pair of particles that "know" exactly what the other is doing - even when they are separated (in this case by a very long distance). This knowledge exchange happens instantaneously (seemingly - certainly much, much more quickly than the speed of light) [but as information can't be transmitted by this mechanism, it doesn't break the rules around relativity and the speed of light which strictly apply to information transmission].

I think what this new announcement is about is using entangled particles as a way to detect if somebody without the appropriate "key" is trying to access the encrypted message. There is a process called decoherence where particles "lose" their quantum mechanical properties (opening the box and looking at the cat for example). This seems to be the way that the encrypted information is destroyed if an unauthorised person tries to read it.

The big deal is the sheer distance over which the particles are separated - an engineering masterpiece by the looks of it.

As to how that is all done - you will need to ask somebody with a nobel prize in physics.

Help. What is the new bit here? This is Einstein's "spooky actions at distance" from the '30s?


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PostPosted: Mon Jun 19, 2017 4:01 pm 
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Torquemada 1420 wrote:
A5D5E5 wrote:
I'm not 6roucho (nor even close), but I'll have a go at explaining this.

Quantum entanglement creates a pair of particles that "know" exactly what the other is doing - even when they are separated (in this case by a very long distance). This knowledge exchange happens instantaneously (seemingly - certainly much, much more quickly than the speed of light) [but as information can't be transmitted by this mechanism, it doesn't break the rules around relativity and the speed of light which strictly apply to information transmission].

I think what this new announcement is about is using entangled particles as a way to detect if somebody without the appropriate "key" is trying to access the encrypted message. There is a process called decoherence where particles "lose" their quantum mechanical properties (opening the box and looking at the cat for example). This seems to be the way that the encrypted information is destroyed if an unauthorised person tries to read it.

The big deal is the sheer distance over which the particles are separated - an engineering masterpiece by the looks of it.

As to how that is all done - you will need to ask somebody with a nobel prize in physics.

Help. What is the new bit here? This is Einstein's "spooky actions at distance" from the '30s?


The new bit is "just" engineering I think. It is certainly spooky action at a distance - but great as he was, Einstein was (seemingly) wrong about it.


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PostPosted: Mon Jun 19, 2017 4:04 pm 
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A5D5E5 wrote:
Torquemada 1420 wrote:
A5D5E5 wrote:
I'm not 6roucho (nor even close), but I'll have a go at explaining this.

Quantum entanglement creates a pair of particles that "know" exactly what the other is doing - even when they are separated (in this case by a very long distance). This knowledge exchange happens instantaneously (seemingly - certainly much, much more quickly than the speed of light) [but as information can't be transmitted by this mechanism, it doesn't break the rules around relativity and the speed of light which strictly apply to information transmission].

I think what this new announcement is about is using entangled particles as a way to detect if somebody without the appropriate "key" is trying to access the encrypted message. There is a process called decoherence where particles "lose" their quantum mechanical properties (opening the box and looking at the cat for example). This seems to be the way that the encrypted information is destroyed if an unauthorised person tries to read it.

The big deal is the sheer distance over which the particles are separated - an engineering masterpiece by the looks of it.

As to how that is all done - you will need to ask somebody with a nobel prize in physics.

Help. What is the new bit here? This is Einstein's "spooky actions at distance" from the '30s?


The new bit is "just" engineering I think. It is certainly spooky action at a distance - but great as he was, Einstein was (seemingly) wrong about it.

Merci


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PostPosted: Mon Jun 19, 2017 5:16 pm 
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Torquemada 1420 wrote:
A5D5E5 wrote:
I'm not 6roucho (nor even close), but I'll have a go at explaining this.

Quantum entanglement creates a pair of particles that "know" exactly what the other is doing - even when they are separated (in this case by a very long distance). This knowledge exchange happens instantaneously (seemingly - certainly much, much more quickly than the speed of light) [but as information can't be transmitted by this mechanism, it doesn't break the rules around relativity and the speed of light which strictly apply to information transmission].

I think what this new announcement is about is using entangled particles as a way to detect if somebody without the appropriate "key" is trying to access the encrypted message. There is a process called decoherence where particles "lose" their quantum mechanical properties (opening the box and looking at the cat for example). This seems to be the way that the encrypted information is destroyed if an unauthorised person tries to read it.

The big deal is the sheer distance over which the particles are separated - an engineering masterpiece by the looks of it.

As to how that is all done - you will need to ask somebody with a nobel prize in physics.

Help. What is the new bit here? This is Einstein's "spooky actions at distance" from the '30s?


Yes.

The basic postulates of schrodinger flavoured non-relativistic quantum mechanics that connect the mathematical theory to observable reality include:

(i) all the information you can get about a quantum system is described mathematically in its wave function (this gives a complex number for every possible state the quantum system could be in if observed),
(ii) that every observation of a quantum system corresponds to a mathematical object called an operator (this is something that maps wave-functions to other wave-functions), and
(iii) the chance you actually observe something is proportional the amplitude of complex number that possibility was given by wave function.
(iv) once you observed something the wave function is "collapsed" and now assigns 100% probability to the observation (technically any possible distinct observable value is an eigenvalue of the observation operator and the wave function collapses to become the associated unique eigenfunction within the Hilbert space you've constructed to understand the quantum system mathematically).

Einstein (and Podolsky and Rosen in Physical Review vol. 47 1935) noticed in the standard maths of QM that it was possible to have two connected quantum systems (called I and II) that get their joint wave-function, you let them separate so they are not interacting (basically no distance term exists in the equations), observe some stuff about the first system (which collapses the wave function), and for the collapsed wave function to specify that the other system is now in the eigenfunction state for some definite measurements (lets say for quantities P and Q). Basically, QM allowed observing system I to make the observation of system II definite:

EPR in 1935 wrote:
This makes the reality of P and Q depend on the process of measurement carried out in the first system, which does not disturb the second system in any way. No reasonable definition of reality could be expected to permit this.


Except that not only does reality permit this... you can actually demonstrate this mad brain bending shit! This effect is what we now call quantum entanglement.

My understanding is that the chinese quantum security mechanism doesn't make uncrackable security but rather it makes it impossible to read (i.e. observe and collapse its quantum state) without that observation being detected.


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PostPosted: Mon Jun 19, 2017 6:03 pm 
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London_Lurker wrote:
Torquemada 1420 wrote:
A5D5E5 wrote:
I'm not 6roucho (nor even close), but I'll have a go at explaining this.

Quantum entanglement creates a pair of particles that "know" exactly what the other is doing - even when they are separated (in this case by a very long distance). This knowledge exchange happens instantaneously (seemingly - certainly much, much more quickly than the speed of light) [but as information can't be transmitted by this mechanism, it doesn't break the rules around relativity and the speed of light which strictly apply to information transmission].

I think what this new announcement is about is using entangled particles as a way to detect if somebody without the appropriate "key" is trying to access the encrypted message. There is a process called decoherence where particles "lose" their quantum mechanical properties (opening the box and looking at the cat for example). This seems to be the way that the encrypted information is destroyed if an unauthorised person tries to read it.

The big deal is the sheer distance over which the particles are separated - an engineering masterpiece by the looks of it.

As to how that is all done - you will need to ask somebody with a nobel prize in physics.

Help. What is the new bit here? This is Einstein's "spooky actions at distance" from the '30s?


Yes.

The basic postulates of schrodinger flavoured non-relativistic quantum mechanics that connect the mathematical theory to observable reality include:

(i) all the information you can get about a quantum system is described mathematically in its wave function (this gives a complex number for every possible state the quantum system could be in if observed),
(ii) that every observation of a quantum system corresponds to a mathematical object called an operator (this is something that maps wave-functions to other wave-functions), and
(iii) the chance you actually observe something is proportional the amplitude of complex number that possibility was given by wave function.
(iv) once you observed something the wave function is "collapsed" and now assigns 100% probability to the observation (technically any possible distinct observable value is an eigenvalue of the observation operator and the wave function collapses to become the associated unique eigenfunction within the Hilbert space you've constructed to understand the quantum system mathematically).

Einstein (and Podolsky and Rosen in Physical Review vol. 47 1935) noticed in the standard maths of QM that it was possible to have two connected quantum systems (called I and II) that get their joint wave-function, you let them separate so they are not interacting (basically no distance term exists in the equations), observe some stuff about the first system (which collapses the wave function), and for the collapsed wave function to specify that the other system is now in the eigenfunction state for some definite measurements (lets say for quantities P and Q). Basically, QM allowed observing system I to make the observation of system II definite:

EPR in 1935 wrote:
This makes the reality of P and Q depend on the process of measurement carried out in the first system, which does not disturb the second system in any way. No reasonable definition of reality could be expected to permit this.


Except that not only does reality permit this... you can actually demonstrate this mad brain bending shit! This effect is what we now call quantum entanglement.

My understanding is that the chinese quantum security mechanism doesn't make uncrackable security but rather it makes it impossible to read (i.e. observe and collapse its quantum state) without that observation being detected.


Einstein had a gift for making great discoveries by getting things wrong.


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PostPosted: Tue Jun 20, 2017 12:15 am 
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London_Lurker wrote:
Torquemada 1420 wrote:
A5D5E5 wrote:
I'm not 6roucho (nor even close), but I'll have a go at explaining this.

Quantum entanglement creates a pair of particles that "know" exactly what the other is doing - even when they are separated (in this case by a very long distance). This knowledge exchange happens instantaneously (seemingly - certainly much, much more quickly than the speed of light) [but as information can't be transmitted by this mechanism, it doesn't break the rules around relativity and the speed of light which strictly apply to information transmission].

I think what this new announcement is about is using entangled particles as a way to detect if somebody without the appropriate "key" is trying to access the encrypted message. There is a process called decoherence where particles "lose" their quantum mechanical properties (opening the box and looking at the cat for example). This seems to be the way that the encrypted information is destroyed if an unauthorised person tries to read it.

The big deal is the sheer distance over which the particles are separated - an engineering masterpiece by the looks of it.

As to how that is all done - you will need to ask somebody with a nobel prize in physics.

Help. What is the new bit here? This is Einstein's "spooky actions at distance" from the '30s?


Yes.

The basic postulates of schrodinger flavoured non-relativistic quantum mechanics that connect the mathematical theory to observable reality include:

(i) all the information you can get about a quantum system is described mathematically in its wave function (this gives a complex number for every possible state the quantum system could be in if observed),
(ii) that every observation of a quantum system corresponds to a mathematical object called an operator (this is something that maps wave-functions to other wave-functions), and
(iii) the chance you actually observe something is proportional the amplitude of complex number that possibility was given by wave function.
(iv) once you observed something the wave function is "collapsed" and now assigns 100% probability to the observation (technically any possible distinct observable value is an eigenvalue of the observation operator and the wave function collapses to become the associated unique eigenfunction within the Hilbert space you've constructed to understand the quantum system mathematically).

Einstein (and Podolsky and Rosen in Physical Review vol. 47 1935) noticed in the standard maths of QM that it was possible to have two connected quantum systems (called I and II) that get their joint wave-function, you let them separate so they are not interacting (basically no distance term exists in the equations), observe some stuff about the first system (which collapses the wave function), and for the collapsed wave function to specify that the other system is now in the eigenfunction state for some definite measurements (lets say for quantities P and Q). Basically, QM allowed observing system I to make the observation of system II definite:

EPR in 1935 wrote:
This makes the reality of P and Q depend on the process of measurement carried out in the first system, which does not disturb the second system in any way. No reasonable definition of reality could be expected to permit this.


Except that not only does reality permit this... you can actually demonstrate this mad brain bending shit! This effect is what we now call quantum entanglement.

My understanding is that the chinese quantum security mechanism doesn't make uncrackable security but rather it makes it impossible to read (i.e. observe and collapse its quantum state) without that observation being detected.



Exactly what I was hoping for, a concise, easily understood summary I can quote in the office.


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PostPosted: Tue Jun 20, 2017 1:01 am 
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JM2K6 wrote:
I read about using quantum entanglement for "unbreakable" security some time last year - really fascinating stuff but I struggle to fully understand the concepts behind it.

I miss 6roucho :(


Give Mad Scientist a shout.


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PostPosted: Tue Jun 20, 2017 1:06 am 
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A5D5E5 wrote:
Torquemada 1420 wrote:
A5D5E5 wrote:
I'm not 6roucho (nor even close), but I'll have a go at explaining this.

Quantum entanglement creates a pair of particles that "know" exactly what the other is doing - even when they are separated (in this case by a very long distance). This knowledge exchange happens instantaneously (seemingly - certainly much, much more quickly than the speed of light) [but as information can't be transmitted by this mechanism, it doesn't break the rules around relativity and the speed of light which strictly apply to information transmission].

I think what this new announcement is about is using entangled particles as a way to detect if somebody without the appropriate "key" is trying to access the encrypted message. There is a process called decoherence where particles "lose" their quantum mechanical properties (opening the box and looking at the cat for example). This seems to be the way that the encrypted information is destroyed if an unauthorised person tries to read it.

The big deal is the sheer distance over which the particles are separated - an engineering masterpiece by the looks of it.

As to how that is all done - you will need to ask somebody with a nobel prize in physics.

Help. What is the new bit here? This is Einstein's "spooky actions at distance" from the '30s?


The new bit is "just" engineering I think. It is certainly spooky action at a distance - but great as he was, Einstein was (seemingly) wrong about it.


Didn't he lose a wager, or some such, or had he karked it before it was confirmed in the 60's?

Could this phenomenon, just possibly, lead to teleportation?


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PostPosted: Tue Jun 20, 2017 1:12 am 
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guy smiley wrote:
London_Lurker wrote:
Torquemada 1420 wrote:
A5D5E5 wrote:
I'm not 6roucho (nor even close), but I'll have a go at explaining this.

Quantum entanglement creates a pair of particles that "know" exactly what the other is doing - even when they are separated (in this case by a very long distance). This knowledge exchange happens instantaneously (seemingly - certainly much, much more quickly than the speed of light) [but as information can't be transmitted by this mechanism, it doesn't break the rules around relativity and the speed of light which strictly apply to information transmission].

I think what this new announcement is about is using entangled particles as a way to detect if somebody without the appropriate "key" is trying to access the encrypted message. There is a process called decoherence where particles "lose" their quantum mechanical properties (opening the box and looking at the cat for example). This seems to be the way that the encrypted information is destroyed if an unauthorised person tries to read it.

The big deal is the sheer distance over which the particles are separated - an engineering masterpiece by the looks of it.

As to how that is all done - you will need to ask somebody with a nobel prize in physics.

Help. What is the new bit here? This is Einstein's "spooky actions at distance" from the '30s?


Yes.

The basic postulates of schrodinger flavoured non-relativistic quantum mechanics that connect the mathematical theory to observable reality include:

(i) all the information you can get about a quantum system is described mathematically in its wave function (this gives a complex number for every possible state the quantum system could be in if observed),
(ii) that every observation of a quantum system corresponds to a mathematical object called an operator (this is something that maps wave-functions to other wave-functions), and
(iii) the chance you actually observe something is proportional the amplitude of complex number that possibility was given by wave function.
(iv) once you observed something the wave function is "collapsed" and now assigns 100% probability to the observation (technically any possible distinct observable value is an eigenvalue of the observation operator and the wave function collapses to become the associated unique eigenfunction within the Hilbert space you've constructed to understand the quantum system mathematically).

Einstein (and Podolsky and Rosen in Physical Review vol. 47 1935) noticed in the standard maths of QM that it was possible to have two connected quantum systems (called I and II) that get their joint wave-function, you let them separate so they are not interacting (basically no distance term exists in the equations), observe some stuff about the first system (which collapses the wave function), and for the collapsed wave function to specify that the other system is now in the eigenfunction state for some definite measurements (lets say for quantities P and Q). Basically, QM allowed observing system I to make the observation of system II definite:

EPR in 1935 wrote:
This makes the reality of P and Q depend on the process of measurement carried out in the first system, which does not disturb the second system in any way. No reasonable definition of reality could be expected to permit this.


Except that not only does reality permit this... you can actually demonstrate this mad brain bending shit! This effect is what we now call quantum entanglement.

My understanding is that the chinese quantum security mechanism doesn't make uncrackable security but rather it makes it impossible to read (i.e. observe and collapse its quantum state) without that observation being detected.



Exactly what I was hoping for, a concise, easily understood summary I can quote in the office.


Absolutely.

"What he said". :nod:


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PostPosted: Tue Jun 20, 2017 3:44 am 
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Ted. wrote:
guy smiley wrote:
London_Lurker wrote:
Torquemada 1420 wrote:
A5D5E5 wrote:
I'm not 6roucho (nor even close), but I'll have a go at explaining this.

Quantum entanglement creates a pair of particles that "know" exactly what the other is doing - even when they are separated (in this case by a very long distance). This knowledge exchange happens instantaneously (seemingly - certainly much, much more quickly than the speed of light) [but as information can't be transmitted by this mechanism, it doesn't break the rules around relativity and the speed of light which strictly apply to information transmission].

I think what this new announcement is about is using entangled particles as a way to detect if somebody without the appropriate "key" is trying to access the encrypted message. There is a process called decoherence where particles "lose" their quantum mechanical properties (opening the box and looking at the cat for example). This seems to be the way that the encrypted information is destroyed if an unauthorised person tries to read it.

The big deal is the sheer distance over which the particles are separated - an engineering masterpiece by the looks of it.

As to how that is all done - you will need to ask somebody with a nobel prize in physics.

Help. What is the new bit here? This is Einstein's "spooky actions at distance" from the '30s?


Yes.

The basic postulates of schrodinger flavoured non-relativistic quantum mechanics that connect the mathematical theory to observable reality include:

(i) all the information you can get about a quantum system is described mathematically in its wave function (this gives a complex number for every possible state the quantum system could be in if observed),
(ii) that every observation of a quantum system corresponds to a mathematical object called an operator (this is something that maps wave-functions to other wave-functions), and
(iii) the chance you actually observe something is proportional the amplitude of complex number that possibility was given by wave function.
(iv) once you observed something the wave function is "collapsed" and now assigns 100% probability to the observation (technically any possible distinct observable value is an eigenvalue of the observation operator and the wave function collapses to become the associated unique eigenfunction within the Hilbert space you've constructed to understand the quantum system mathematically).

Einstein (and Podolsky and Rosen in Physical Review vol. 47 1935) noticed in the standard maths of QM that it was possible to have two connected quantum systems (called I and II) that get their joint wave-function, you let them separate so they are not interacting (basically no distance term exists in the equations), observe some stuff about the first system (which collapses the wave function), and for the collapsed wave function to specify that the other system is now in the eigenfunction state for some definite measurements (lets say for quantities P and Q). Basically, QM allowed observing system I to make the observation of system II definite:

EPR in 1935 wrote:
This makes the reality of P and Q depend on the process of measurement carried out in the first system, which does not disturb the second system in any way. No reasonable definition of reality could be expected to permit this.


Except that not only does reality permit this... you can actually demonstrate this mad brain bending shit! This effect is what we now call quantum entanglement.

My understanding is that the chinese quantum security mechanism doesn't make uncrackable security but rather it makes it impossible to read (i.e. observe and collapse its quantum state) without that observation being detected.



Exactly what I was hoping for, a concise, easily understood summary I can quote in the office.


Absolutely.

"What he said". :nod:


:thumbup: PR to the rescue...again.

Mind you, by the time I've reached the office, there will be some slight modifications, I fear. :?


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PostPosted: Tue Jun 20, 2017 11:26 am 
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Ted. wrote:
A5D5E5 wrote:
Torquemada 1420 wrote:
A5D5E5 wrote:
I'm not 6roucho (nor even close), but I'll have a go at explaining this.

Quantum entanglement creates a pair of particles that "know" exactly what the other is doing - even when they are separated (in this case by a very long distance). This knowledge exchange happens instantaneously (seemingly - certainly much, much more quickly than the speed of light) [but as information can't be transmitted by this mechanism, it doesn't break the rules around relativity and the speed of light which strictly apply to information transmission].

I think what this new announcement is about is using entangled particles as a way to detect if somebody without the appropriate "key" is trying to access the encrypted message. There is a process called decoherence where particles "lose" their quantum mechanical properties (opening the box and looking at the cat for example). This seems to be the way that the encrypted information is destroyed if an unauthorised person tries to read it.

The big deal is the sheer distance over which the particles are separated - an engineering masterpiece by the looks of it.

As to how that is all done - you will need to ask somebody with a nobel prize in physics.

Help. What is the new bit here? This is Einstein's "spooky actions at distance" from the '30s?


The new bit is "just" engineering I think. It is certainly spooky action at a distance - but great as he was, Einstein was (seemingly) wrong about it.


Didn't he lose a wager, or some such, or had he karked it before it was confirmed in the 60's?

Could this phenomenon, just possibly, lead to teleportation?


If you mean "Standing on a circle with Spock and the unnamed bloke who is obviously going to die, going all wavy and then reappearing on an obviously fake alien planet" type of teleportation then no. Entanglement is a purely quantum mechanical effect.

If you mean "Transferring some quantum mechanical information about a particle and using that to replicate the quantum state of that particle some distance away" type of teleportation then it has already been in the "can do" box for about 25 years. It is pretty disappointing though compared to Star Trek - still limited to the speed of light and you essentially need to visit the chosen destination first to set up the "pathway".


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PostPosted: Tue Jun 20, 2017 12:12 pm 
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The Numberphile guys will have a work around.


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PostPosted: Tue Jun 20, 2017 12:37 pm 
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A5D5E5 wrote:
London_Lurker wrote:
Torquemada 1420 wrote:
A5D5E5 wrote:
I'm not 6roucho (nor even close), but I'll have a go at explaining this.

Quantum entanglement creates a pair of particles that "know" exactly what the other is doing - even when they are separated (in this case by a very long distance). This knowledge exchange happens instantaneously (seemingly - certainly much, much more quickly than the speed of light) [but as information can't be transmitted by this mechanism, it doesn't break the rules around relativity and the speed of light which strictly apply to information transmission].

I think what this new announcement is about is using entangled particles as a way to detect if somebody without the appropriate "key" is trying to access the encrypted message. There is a process called decoherence where particles "lose" their quantum mechanical properties (opening the box and looking at the cat for example). This seems to be the way that the encrypted information is destroyed if an unauthorised person tries to read it.

The big deal is the sheer distance over which the particles are separated - an engineering masterpiece by the looks of it.

As to how that is all done - you will need to ask somebody with a nobel prize in physics.

Help. What is the new bit here? This is Einstein's "spooky actions at distance" from the '30s?


Yes.

The basic postulates of schrodinger flavoured non-relativistic quantum mechanics that connect the mathematical theory to observable reality include:

(i) all the information you can get about a quantum system is described mathematically in its wave function (this gives a complex number for every possible state the quantum system could be in if observed),
(ii) that every observation of a quantum system corresponds to a mathematical object called an operator (this is something that maps wave-functions to other wave-functions), and
(iii) the chance you actually observe something is proportional the amplitude of complex number that possibility was given by wave function.
(iv) once you observed something the wave function is "collapsed" and now assigns 100% probability to the observation (technically any possible distinct observable value is an eigenvalue of the observation operator and the wave function collapses to become the associated unique eigenfunction within the Hilbert space you've constructed to understand the quantum system mathematically).

Einstein (and Podolsky and Rosen in Physical Review vol. 47 1935) noticed in the standard maths of QM that it was possible to have two connected quantum systems (called I and II) that get their joint wave-function, you let them separate so they are not interacting (basically no distance term exists in the equations), observe some stuff about the first system (which collapses the wave function), and for the collapsed wave function to specify that the other system is now in the eigenfunction state for some definite measurements (lets say for quantities P and Q). Basically, QM allowed observing system I to make the observation of system II definite:

EPR in 1935 wrote:
This makes the reality of P and Q depend on the process of measurement carried out in the first system, which does not disturb the second system in any way. No reasonable definition of reality could be expected to permit this.


Except that not only does reality permit this... you can actually demonstrate this mad brain bending shit! This effect is what we now call quantum entanglement.

My understanding is that the chinese quantum security mechanism doesn't make uncrackable security but rather it makes it impossible to read (i.e. observe and collapse its quantum state) without that observation being detected.


Einstein had a gift for making great discoveries by getting things wrong.


Einstein's field equations. Stick in a Lambda, ditch the lambda... now it seems we've got the lambda back (dark energy term...). I'm a mathematician so tend not to be very hot on the physical interpretations but the maths behind QM, QFT and general relativity is fascinating.


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PostPosted: Tue Jun 20, 2017 12:39 pm 
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guy smiley wrote:
London_Lurker wrote:
Torquemada 1420 wrote:
A5D5E5 wrote:
I'm not 6roucho (nor even close), but I'll have a go at explaining this.

Quantum entanglement creates a pair of particles that "know" exactly what the other is doing - even when they are separated (in this case by a very long distance). This knowledge exchange happens instantaneously (seemingly - certainly much, much more quickly than the speed of light) [but as information can't be transmitted by this mechanism, it doesn't break the rules around relativity and the speed of light which strictly apply to information transmission].

I think what this new announcement is about is using entangled particles as a way to detect if somebody without the appropriate "key" is trying to access the encrypted message. There is a process called decoherence where particles "lose" their quantum mechanical properties (opening the box and looking at the cat for example). This seems to be the way that the encrypted information is destroyed if an unauthorised person tries to read it.

The big deal is the sheer distance over which the particles are separated - an engineering masterpiece by the looks of it.

As to how that is all done - you will need to ask somebody with a nobel prize in physics.

Help. What is the new bit here? This is Einstein's "spooky actions at distance" from the '30s?


Yes.

The basic postulates of schrodinger flavoured non-relativistic quantum mechanics that connect the mathematical theory to observable reality include:

(i) all the information you can get about a quantum system is described mathematically in its wave function (this gives a complex number for every possible state the quantum system could be in if observed),
(ii) that every observation of a quantum system corresponds to a mathematical object called an operator (this is something that maps wave-functions to other wave-functions), and
(iii) the chance you actually observe something is proportional the amplitude of complex number that possibility was given by wave function.
(iv) once you observed something the wave function is "collapsed" and now assigns 100% probability to the observation (technically any possible distinct observable value is an eigenvalue of the observation operator and the wave function collapses to become the associated unique eigenfunction within the Hilbert space you've constructed to understand the quantum system mathematically).

Einstein (and Podolsky and Rosen in Physical Review vol. 47 1935) noticed in the standard maths of QM that it was possible to have two connected quantum systems (called I and II) that get their joint wave-function, you let them separate so they are not interacting (basically no distance term exists in the equations), observe some stuff about the first system (which collapses the wave function), and for the collapsed wave function to specify that the other system is now in the eigenfunction state for some definite measurements (lets say for quantities P and Q). Basically, QM allowed observing system I to make the observation of system II definite:

EPR in 1935 wrote:
This makes the reality of P and Q depend on the process of measurement carried out in the first system, which does not disturb the second system in any way. No reasonable definition of reality could be expected to permit this.


Except that not only does reality permit this... you can actually demonstrate this mad brain bending shit! This effect is what we now call quantum entanglement.

My understanding is that the chinese quantum security mechanism doesn't make uncrackable security but rather it makes it impossible to read (i.e. observe and collapse its quantum state) without that observation being detected.



Exactly what I was hoping for, a concise, easily understood summary I can quote in the office.


Sad thing is I thought that was pretty concise :(( .

Its like when I write a paper and my PI/boss C&Ps 80% of what I've written into the supporting information.


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PostPosted: Tue Jun 20, 2017 12:44 pm 
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London_Lurker wrote:
A5D5E5 wrote:
London_Lurker wrote:
Torquemada 1420 wrote:
A5D5E5 wrote:
I'm not 6roucho (nor even close), but I'll have a go at explaining this.

Quantum entanglement creates a pair of particles that "know" exactly what the other is doing - even when they are separated (in this case by a very long distance). This knowledge exchange happens instantaneously (seemingly - certainly much, much more quickly than the speed of light) [but as information can't be transmitted by this mechanism, it doesn't break the rules around relativity and the speed of light which strictly apply to information transmission].

I think what this new announcement is about is using entangled particles as a way to detect if somebody without the appropriate "key" is trying to access the encrypted message. There is a process called decoherence where particles "lose" their quantum mechanical properties (opening the box and looking at the cat for example). This seems to be the way that the encrypted information is destroyed if an unauthorised person tries to read it.

The big deal is the sheer distance over which the particles are separated - an engineering masterpiece by the looks of it.

As to how that is all done - you will need to ask somebody with a nobel prize in physics.

Help. What is the new bit here? This is Einstein's "spooky actions at distance" from the '30s?


Yes.

The basic postulates of schrodinger flavoured non-relativistic quantum mechanics that connect the mathematical theory to observable reality include:

(i) all the information you can get about a quantum system is described mathematically in its wave function (this gives a complex number for every possible state the quantum system could be in if observed),
(ii) that every observation of a quantum system corresponds to a mathematical object called an operator (this is something that maps wave-functions to other wave-functions), and
(iii) the chance you actually observe something is proportional the amplitude of complex number that possibility was given by wave function.
(iv) once you observed something the wave function is "collapsed" and now assigns 100% probability to the observation (technically any possible distinct observable value is an eigenvalue of the observation operator and the wave function collapses to become the associated unique eigenfunction within the Hilbert space you've constructed to understand the quantum system mathematically).

Einstein (and Podolsky and Rosen in Physical Review vol. 47 1935) noticed in the standard maths of QM that it was possible to have two connected quantum systems (called I and II) that get their joint wave-function, you let them separate so they are not interacting (basically no distance term exists in the equations), observe some stuff about the first system (which collapses the wave function), and for the collapsed wave function to specify that the other system is now in the eigenfunction state for some definite measurements (lets say for quantities P and Q). Basically, QM allowed observing system I to make the observation of system II definite:

EPR in 1935 wrote:
This makes the reality of P and Q depend on the process of measurement carried out in the first system, which does not disturb the second system in any way. No reasonable definition of reality could be expected to permit this.


Except that not only does reality permit this... you can actually demonstrate this mad brain bending shit! This effect is what we now call quantum entanglement.

My understanding is that the chinese quantum security mechanism doesn't make uncrackable security but rather it makes it impossible to read (i.e. observe and collapse its quantum state) without that observation being detected.


Einstein had a gift for making great discoveries by getting things wrong.


Einstein's field equations. Stick in a Lambda, ditch the lambda... now it seems we've got the lambda back (dark energy term...). I'm a mathematician so tend not to be very hot on the physical interpretations but the maths behind QM, QFT and general relativity is fascinating.


That is exactly what I had in mind - if the cosmological constant turns out to be dark energy then it would be a remarkable discovery via an unorthodox route.

The maths is utterly wonderful - it is what got me interested in these subjects long before the sheer wonder of what they say about the world grabbed me.


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PostPosted: Tue Jun 20, 2017 12:47 pm 
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A5D5E5 wrote:
London_Lurker wrote:
A5D5E5 wrote:

Einstein had a gift for making great discoveries by getting things wrong.


Einstein's field equations. Stick in a Lambda, ditch the lambda... now it seems we've got the lambda back (dark energy term...). I'm a mathematician so tend not to be very hot on the physical interpretations but the maths behind QM, QFT and general relativity is fascinating.


That is exactly what I had in mind - if the cosmological constant turns out to be dark energy then it would be a remarkable discovery via an unorthodox route.

The maths is utterly wonderful - it is what got me interested in these subjects long before the sheer wonder of what they say about the world grabbed me.


:thumbup: :nod:


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PostPosted: Tue Jun 20, 2017 12:48 pm 
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London_Lurker wrote:
guy smiley wrote:
London_Lurker wrote:
Torquemada 1420 wrote:
A5D5E5 wrote:
I'm not 6roucho (nor even close), but I'll have a go at explaining this.

Quantum entanglement creates a pair of particles that "know" exactly what the other is doing - even when they are separated (in this case by a very long distance). This knowledge exchange happens instantaneously (seemingly - certainly much, much more quickly than the speed of light) [but as information can't be transmitted by this mechanism, it doesn't break the rules around relativity and the speed of light which strictly apply to information transmission].

I think what this new announcement is about is using entangled particles as a way to detect if somebody without the appropriate "key" is trying to access the encrypted message. There is a process called decoherence where particles "lose" their quantum mechanical properties (opening the box and looking at the cat for example). This seems to be the way that the encrypted information is destroyed if an unauthorised person tries to read it.

The big deal is the sheer distance over which the particles are separated - an engineering masterpiece by the looks of it.

As to how that is all done - you will need to ask somebody with a nobel prize in physics.

Help. What is the new bit here? This is Einstein's "spooky actions at distance" from the '30s?


Yes.

The basic postulates of schrodinger flavoured non-relativistic quantum mechanics that connect the mathematical theory to observable reality include:

(i) all the information you can get about a quantum system is described mathematically in its wave function (this gives a complex number for every possible state the quantum system could be in if observed),
(ii) that every observation of a quantum system corresponds to a mathematical object called an operator (this is something that maps wave-functions to other wave-functions), and
(iii) the chance you actually observe something is proportional the amplitude of complex number that possibility was given by wave function.
(iv) once you observed something the wave function is "collapsed" and now assigns 100% probability to the observation (technically any possible distinct observable value is an eigenvalue of the observation operator and the wave function collapses to become the associated unique eigenfunction within the Hilbert space you've constructed to understand the quantum system mathematically).

Einstein (and Podolsky and Rosen in Physical Review vol. 47 1935) noticed in the standard maths of QM that it was possible to have two connected quantum systems (called I and II) that get their joint wave-function, you let them separate so they are not interacting (basically no distance term exists in the equations), observe some stuff about the first system (which collapses the wave function), and for the collapsed wave function to specify that the other system is now in the eigenfunction state for some definite measurements (lets say for quantities P and Q). Basically, QM allowed observing system I to make the observation of system II definite:

EPR in 1935 wrote:
This makes the reality of P and Q depend on the process of measurement carried out in the first system, which does not disturb the second system in any way. No reasonable definition of reality could be expected to permit this.


Except that not only does reality permit this... you can actually demonstrate this mad brain bending shit! This effect is what we now call quantum entanglement.

My understanding is that the chinese quantum security mechanism doesn't make uncrackable security but rather it makes it impossible to read (i.e. observe and collapse its quantum state) without that observation being detected.



Exactly what I was hoping for, a concise, easily understood summary I can quote in the office.


Sad thing is I thought that was pretty concise :(( .

Its like when I write a paper and my PI/boss C&Ps 80% of what I've written into the supporting information.


It was concise ... for anyone with a working knowledge of Hamiltonians, partial differential equations and vector spaces.


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PostPosted: Tue Jun 20, 2017 12:50 pm 
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London_Lurker wrote:

Sad thing is I thought that was pretty concise :(( .

Its like when I write a paper and my PI/boss C&Ps 80% of what I've written into the supporting information.


Actually I followed it ok, roughly speaking. I'm a layman with this stuff. Wish I'd followed it from school to uni to be honest, it's fascinating and I was always good with abstract stuff and maths. Your summary was good. I was being a smartass.


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PostPosted: Tue Jun 20, 2017 12:53 pm 
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guy smiley wrote:
London_Lurker wrote:

Sad thing is I thought that was pretty concise :(( .

Its like when I write a paper and my PI/boss C&Ps 80% of what I've written into the supporting information.


Actually I followed it ok, roughly speaking. I'm a layman with this stuff. Wish I'd followed it from school to uni to be honest, it's fascinating and I was always good with abstract stuff and maths. Your summary was good. I was being a smartass.


Cheers! Anyway, I better log off and get back to the abstract stuff.


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PostPosted: Tue Jun 20, 2017 12:59 pm 
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guy smiley wrote:

Exactly what I was hoping for, a concise, easily understood summary I can quote in the office.

:lol:

Bohm's work on this stuff was fascinating.


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