Caught on camera: quantum mechanics in action

Aug 08, 2012

(Phys.org) -- Scientists at the University of Glasgow have captured images of ‘quantum entanglement’ on camera for the first time.

In , is one of the bizarre behaviours exhibited by particles where the rules of classical physics are broken and seemingly impossible events are a reality.

Described by Einstein as ‘spooky action at a distance’, entanglement is the phenomenon whereby two particles act as one system even when separated by immense distances.

The entangled particles are in a superposition where their individual state isn’t known. However, as soon as one of them is measured or observed the other will take on a correlated state instantaneously, seemingly violating the speed of light.

Being able to exploit such behaviour would have major applications in communications encryption and could underpin the next generation of computer technology, known as quantum computation.

The team in the School of Physics and Astronomy comprising Matthew Edgar, Daniel Tasca and Professor Miles Padgett, have taken a step towards the development of such applications by measuring strong spatial entanglement of photons – particles of light - using a highly-sensitive camera. Making use of a 201 by 201 pixel array, the camera could observe the full field of the quantum light at the same time, allowing the team to see up to 2,500 different entangled dimensions or states.

Entangled photons can be created by using a special crystal to split one photon into two.

By taking pictures of pairs of photons the researchers measured correlations in the photons’ positions to a degree that is not allowed according to classical physics.

Prof Padgett, said: “The maxim: A picture tells a thousand words is nowhere more true than here where each pixel contains its own information, potentially revolutionising the data capacity of quantum secured communication.

“This research is an important step towards future quantum technologies and more generally shows that cameras can lead to important new capabilities in quantum information science.”

The research, ‘Imaging high-dimensional spatial entanglement with a ’, was conducted in collaboration with researchers at Heriot-Watt University and the University of Ottawa and is published in Nature Communications.

Explore further: A new key to unlocking the mysteries of physics? Quantum turbulence

More information: www.nature.com/ncomms/journal/v3/n8/full/ncomms1988.html

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User comments : 50

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Jitterbewegung
5 / 5 (16) Aug 08, 2012
However you cannot see the picture and read the article at the same time;-)
Shoss
1 / 5 (5) Aug 08, 2012
"However, as soon as one of them is measured or observed the other will take on a correlated state instantaneously, seemingly violating the speed of light."

False
Satene
1 / 5 (9) Aug 08, 2012
IMO the light speed is really violated during this, but the observation becomes indeterministic during this. You can imagine it like the sending of two ripples along water surface. These ripples may interfere mutually under formation of much faster underwater sound wave and recombine again at the target. You will gain the speed, but you will lose the information about (position of) actual source of both ripples. The special relativity just prohibits to observe superluminal motion deterministically. If you will dissolve itself from sight, jump with superluminal speed and condense again during this, then the special relativity has absolute no problem with it - it just handles such a situation as two causally separated states.
Tektrix
5 / 5 (4) Aug 08, 2012
"However, as soon as one of them is measured or observed the other will take on a correlated state instantaneously, seemingly violating the speed of light."

False


For the sake of discussion, it would be cool if you could substantiate your opinion. I understand if you don't want to, though.
seb
5 / 5 (1) Aug 08, 2012
" seemingly violating the speed of light."

False


Key word: seemingly.
JCheverie
5 / 5 (2) Aug 08, 2012
However you cannot see the picture and read the article at the same time;-)


Clever!
Erik
not rated yet Aug 08, 2012
Perhaps Cramer's "Transactional Interpretation of QM" applies. He proposes that the QM waves go forwards & backwards in time. Thus, either particle is linked backwards in time to the moment of creation of the pair, & then forward in time to the other partner of the pair. The waves always are limited by the speed of light, but create the appearance of a superluminal event.
Satene
1 / 5 (6) Aug 08, 2012
He proposes that the QM waves go forwards & backwards in time
They're doing it routinely - it just depends, how we define such a time travel. IMO the object travels in entropic time forward / backward in every moment, when it dissolves / evaporates or condenses. It's behaviour similar to density fluctuations in dense gas. This animation is a snapshot of quantum wave in gravity potential as simulated with Schrodinger equation, so it cannot evaporate into infinity.
Tangent2
1 / 5 (2) Aug 08, 2012
"However, as soon as one of them is measured or observed the other will take on a correlated state instantaneously, seemingly violating the speed of light."

False


Care to elaborate?
Modernmystic
1 / 5 (4) Aug 08, 2012
If one particle changes instantly across a light year in response to a measurement then yes light speed is definitely being surpassed on some level.

If there is no instantaneous response then it isn't.

It's that simple. Have your cake, or eat it.
Claudius
1.7 / 5 (6) Aug 08, 2012
If one particle changes instantly across a light year in response to a measurement then yes light speed is definitely being surpassed on some level.

If there is no instantaneous response then it isn't.

It's that simple. Have your cake, or eat it.


There is another interpretation that simplifies this issue. In David Deutsch's multiverse theory, the event that creates the photons exists in multiple universes. When you measure one of the photons, the other photon does not change, rather you are finding out which universe you are in. In a different universe, you would get a different result. No magic is required, no spooky action at a distance, no violation of speed of light.
Claudius
1.7 / 5 (6) Aug 08, 2012
Another example from David Deutsch's theory. Schroedinger's cat's existence depends on an unpredictable, random event. What happens is that the cats (in different universes) begin to randomly die whenever the event occurs. What happens when you open the lid to check on the cat's condition is that you are finding out which universe you are in, a universe where the cat is still alive, or one in which it has died.
Telekinetic
1 / 5 (2) Aug 08, 2012
Don't forget the infinite simultaneous outcomes in Deutsch's multiverse- you may be picnicking in the South of France while another incarnation of you is taking snapshots of entangled pairs.
Modernmystic
1 / 5 (4) Aug 08, 2012
There is another interpretation that simplifies this issue.


Which, while interesting, is exactly what I said. The particle either changes or it doesn't. If it doesn't no superluminal phenomena are involved.

rather you are finding out which universe you are in


I like to think of it more as you're putting yourself in one universe. In fact we're doing it all the time every day by every choice we make.
Telekinetic
3.7 / 5 (6) Aug 08, 2012
In a different universe, you would get a different result. No magic is required, no spooky action at a distance
Of course, at the moment when we consider alternate Universe, a lotta magic and spookiness will disappear immediately and everything will went quite normally...;-) But I don't want to believe in such an Universe, until I can use quite down-to-earth models and analogies based on water surface, particles and ripples.

But you can have your version in the multiverse, while another version of yourself is laughing uproariously at your theory.
sanita
1 / 5 (4) Aug 08, 2012
The factual relevancy of multiverse concept is apparently similar to the concept of God: you can consider or explain what you want with it.
Claudius
1 / 5 (5) Aug 08, 2012
But I don't want to believe in such an Universe, until I can use quite down-to-earth models and analogies based on water surface, particles and ripples.

You should read "The Fabric of the Universe" by David Deutsch. He starts out with what he feels is experimental evidence of parallel universes and goes from there.
The particle either changes or it doesn't.

In this theory, it always doesn't. It has different states depending on which universe it is in, but within a universe the particles don't change after the event that creates them.
I like to think of it more as you're putting yourself in one universe. In fact we're doing it all the time every day by every choice we make.

This is an obvious result of the theory. What David Deutsch doesn't want to discuss is how this allows for free will, for some reason.
Claudius
1.8 / 5 (5) Aug 08, 2012
The factual relevancy of multiverse concept is apparently similar to the concept of God: you can consider or explain what you want with it.


Yes, except I don't know of any experimental evidence for the concept of God.
sanita
1 / 5 (10) Aug 08, 2012
IMO existence of some phenomena (like the stigmata) are way more reliable existence of God, than the existence of multiverse. Until we don't consider the parallel universe, which is accidentally full of stigmatized people, indeed.
Telekinetic
3 / 5 (6) Aug 08, 2012
IMO existence of some phenomena (like http://en.wikiped...tigmata) are way more reliable existence of God, than the existence of multiverse. Until we don't consider the parallel universe, which is accidentally full of stigmatized people, indeed.

Belief can be strong enough in some as to cause physiological events.

sanita
1 / 5 (7) Aug 08, 2012
Sounds nice except we have no evidence for such an explanation. Stigmata are often permanent injures and no other subcutaneous wounds caused with psychical state were described. Not to say, we have no biochemical theory for such physiological "event", the evolutionary meaning of it the less. You're just believing in its rational explanation in the same way, like other people believe in miracles - that's all.
Telekinetic
1 / 5 (6) Aug 08, 2012
Actually, I don't think there necessarily is "always a scientific explanation" for everything. That's my opinion, though. I've personally witnessed things outside the realm of known science. I do think that the human mind can actuate physical manifestations like stigmata, because the mind controls the body in ways that aren't fully understood.
Karl Kognition
5 / 5 (2) Aug 08, 2012
The article has nothing to do with the supernatural. If you think it does, such that it pertains to a god, state your definition of that god. If the logic of that being's existense is sound and its presence can produce proper predictive models of reality then you may proceed to infer the correlation. Otherwise, please leave religious tyings out of the discussion; they currently hold no merit.
Telekinetic
2.3 / 5 (6) Aug 08, 2012
It's a miracle that by registering on Physorg today in order to make your very first comment right here as a sock puppet, you think you won't be considered a jerk. But here you are, attempting to enlist the predisposition of the forum to be in league with you just for a measly rating. By the cadence of your writing, I'd say you're really aroc91. Am I right?
Karl Kognition
5 / 5 (4) Aug 09, 2012
@Telekinetic, no, you aren't. And wow at the ad hominem. That was my first comment! Woot. And this my second! Ratings! It's all about the ratings! I winrar! Yes, I did sign up today. Nice and easy with Facebook. And yes, I did sign up pretty much because I wanted to refute your arguments.

Actually, I don't think there necessarily is "always a scientific explanation" for everything. That's my opinion, though. I've personally witnessed things outside the realm of known science. I do think that the human mind can actuate physical manifestations like stigmata, because the mind controls the body in ways that aren't fully understood.


Now, saying you've witnessed things outside the realm of science, what are these and why do you consider them unexplanable through the scientific method? (Also, why is it related to this article?).
Karl Kognition
5 / 5 (2) Aug 09, 2012
@Telekinetic. If an answer is currently not available it is an unknown. I hope you aren't providing an argument from ignorance and saying because your current theory on these mysterious events of yours aren't shown as incorrect they are correct. Or that you are committing the god of the gaps fallacy.

What are you saying? And how is it related to this article?
Tausch
1 / 5 (2) Aug 09, 2012
All religion is inaccessable to the scientific method.
All human behavior attributed to religion is accessible to the scientific method.

Thank God.
Karl Kognition
not rated yet Aug 09, 2012
No one is answering my questions and so far replies are dragging the discussion further and further off topic and contribute nothing of merit. I read the commenting guidelines; PM me if you want to debate what you are posting about.
Torbjorn_Larsson_OM
5 / 5 (4) Aug 09, 2012
@ Satene, ModernMystic:

You are confusing correlation with causation. The correlated values has to be compared for an observer to extract state values, and that comparison can only be done relativistically.

This is QM101. That quantum mechanics obeys relativity is witnessed by a) Bell test experiments, some of which are the lowest uncertainty in physics, b) relativistic quantum field theory, c) the ability to quantize general relativity at low energies. Google "Bell test experiments wiki".

@ Erik, Satene:

QM waves go forward in time as we all do. Nothing has ever been observed to go backwards, and that would break relativistic causality. See above how we know that doesn't happen.
Thrasymachus
1.8 / 5 (5) Aug 09, 2012
From the perspective of a photon, the entire universe is a single point. There is no distance between anything. Time, for a photon, is also only as long as it takes to emit or absorb it, there is no time between emission and absorption for a photon. When there are two photons, from their perspective, they exist in the same place, overlapping each other. When you create a photon and then split it using a special crystal to create two entangled photons, what you're doing is analogous to taking a coin and splitting it down the middle, then putting both halves in their own boxes and shipping one to your friend on the other side of the world. When you look in your box and see that you've got the "heads" half, you know that your friend has the "tails" half instantly, indeed, you could know it faster than light could transmit that information to you from him. But that's not faster than light information travel. It's just being able to deduce before confirmation can arrive.
Torbjorn_Larsson_OM
5 / 5 (1) Aug 09, 2012
"Which, while interesting, is exactly what I said. The particle either changes or it doesn't."

Many World Theory is a possibility, and it is consistent with the concept that an observation doesn't have a specific state before it is observed within a single MWT universe. The states never change, it is the Many World that branches. Deutsch adds some dynamic to that when he discuss time in his "The Fabric of Reality", but that isn't necessary.

MWT is testable in the sense that decoherence theory seems to be, e.g. it isn't fully testable but QM continues to be tested. It is also a parsimonious theory on constraints needed.

Another possibility is the simplest based on current physics, decoherence QM and lightcone physics. I prefer that one.
Torbjorn_Larsson_OM
3.5 / 5 (2) Aug 09, 2012
[cont]

Here it becomes obvious that spacetime doesn't behave like classical spacetime.

Penrose twistor space description, marrying QM with relativity, shows how a local point in the underlying twistor space can map to light separated points in spacetime. Entanglement becomes non-mysterious if it is different particle within the same small spatial volume, just a mapping issue between spaces.

Also cosmological time becomes locally revised, as entanglements have to be decohered and lightcone compared as per my first comment, before the entangled system volume "catches up" with the clock expansion sets up. The cosmological horizon protects decoherence as it does other physics by redshifting signals towards zero energy, hence local time will always "catch up".

@ Thrasymachus:

Indeed, correlation not causation.
Satene
1 / 5 (2) Aug 09, 2012
..quantum mechanics obeys relativity is witnessed..
a) The article abstract itself notes, that the experiment "demonstrate EinsteinPodolskyRosen type correlations by more than two orders of magnitude". EPR correlations connect parallel observation of non-commuting and discrete quantities, which should never happen in rigorous QM. b) Bell tests are valid only locally. c) quantization of general relativity at middle and high energies wasn't developed yet. Of course, locally every theory is correct, if you define its locality in sufficiently stringent way. Locally I can feel as a president of the Earth, for example.
Torbjorn_Larsson_OM
5 / 5 (1) Aug 09, 2012
@ Satene:

As I said, Bell test experiments follow "rigorous QM" and relativity both. You are avoiding the very clear physics here, and it is easy to check as I suggested.

The point with the experiments are precisely that they study systems that are non-local. You are confusing that with the concept of local hidden variables, those that aren't transmitted during the experiments because the experiments show that they would go ftl. Instead correlations explain what is seen. Read Bell et al on the set up and physics of these experiments.

Btw, no one knows how to quantize general relativity for high energies, where GR breaks down as a description of gravity and spacetime both. I was making the point that QM and relativity is fundamentally compatible.
Torbjorn_Larsson_OM
5 / 5 (1) Aug 09, 2012
How come every quantum mechanic article becomes a reason to discuss woo?

@ sanita:

Many World Theory is not a multiverse cosmology in the sense that multiverses can causally reconnect after separation in theory. MWT has a more basic structure.

Both are likely testable, see my previous comment on MWT testability progress, and multiverse cosmologies are testable by way of anthropic theory.
Torbjorn_Larsson_OM
3.4 / 5 (5) Aug 09, 2012
@ Tausch:

Creationists shouldn't comment on science, it is hilarious.

All religion is accessible to the scientific method.

We know that intercessory prayer studies shows prayers doesn't work. So the gods that listens to prayers - they do not exist.

We know that the mind is embodied. So the gods that creates souls - they do not exist.

We know how species evolves. So the gods that creates humans - they do not exist.

We now know that physics laws must result in universes. So the gods that creates universes - they do not exist.

We know that most likely physics laws comes out of selection on universes. And no, that isn't circular since observation and testing of constraints always breaks circularity out of constraints. So the gods that creates laws - they likely do not exist.

The remaining non-magical gods are non-creationist non-deist pantheist, equating the universe with gods. And such gods may as well be taken - to not exist.
Telekinetic
1 / 5 (3) Aug 09, 2012

@aroc91/Karl Kognition:

aroc91 Aug 24, 2011 Rank: 5 / 5 (6) Indeed. Good article. The god of the gaps is getting smaller by the day.

I WAS right, you nincompoop.

roboferret
not rated yet Aug 09, 2012

@aroc91/Karl Kognition:

aroc91 Aug 24, 2011 Rank: 5 / 5 (6) Indeed. Good article. The god of the gaps is getting smaller by the day.

I WAS right, you nincompoop.



You do know "the god of the gaps" is a phrase invented and popularised by Richard Dawkins?
Telekinetic
1 / 5 (2) Aug 09, 2012

@aroc91/Karl Kognition:

aroc91 Aug 24, 2011 Rank: 5 / 5 (6) Indeed. Good article. The god of the gaps is getting smaller by the day.

I WAS right, you nincompoop.



You do know "the god of the gaps" is a phrase invented and popularised by Richard Dawkins?

Yes, and aroc91 has used it twice on this forum, but as his sock puppet Karl Kognition the second time. He was also "orac" for a while before I busted him.
JOAT MON
1 / 5 (1) Aug 09, 2012
The Copenhagen interpretation was traditionally the most popular among physicists, next to a purely instrumentalist position that denies any need for explanation (a view expressed in David Mermin's famous quote "shut up and calculate", often misattributed to Richard Feynman.[1]) However, the many-worlds interpretation has been gaining acceptance;[2] a controversial poll mentioned in "The Physics of Immortality" (published in 1994), of 72 "leading cosmologists and other quantum field theorists" found that 58% supported the many-worlds interpretation, including Stephen Hawking and Nobel laureates Murray Gell-Mann and Richard Feynman.[3] Moreover, the instrumentalist position has been challenged by proposals for falsifiable experiments that might one day distinguish interpretations, e.g. by measuring an AI consciousness[4] or via quantum computing.[5]
JOAT MON
1 / 5 (1) Aug 09, 2012
Quote taken from Wikipedia page "Interpretations of quantum mechanics"
Footnotes would be listed below but every time I try to add them to the comment PhysOrg marks the as spam.. FAIL :(
JOAT MON
1 / 5 (1) Aug 09, 2012
Most relevant to the discussion are of course, footnotes [4] and [5] both attributed to David Deutsch, "Quantum theory as a universal physical theory", and "Three connections between Everett's interpretation and experiment Quantum Concepts of Space and Time".
Telekinetic
2 / 5 (4) Aug 09, 2012
I received these 2 PM's today from Karl Kognition:
"Karl Kognition 3hr40min ago- Look, you f---, my name is Karl Zuvela and I go by the name of Karl Kognition online. Stop calling me a sock. Who the f--- is aroc91? Would you like some evidence of my existence?
Karl Kognition 3hr34min ago- Or are you just a troll? You're doing a good job of pissing me off and I've tried my best to avoid ad hominems, It's your arguments I do not agree with, not you. At least, I didn't, until you kept attacking me."

Telekinetic
1 / 5 (3) Aug 09, 2012
OH, MY!!! I don't want to mess with Karl Zuvela!

http://www.google...h?q=Karl Zuvela&hl=en&client=safari&sa=X&rls=en&prmd=imvnso&tbm=isch&tbo=u&source=univ&ei=I_0jUNtuiNnRAeD1gdAI&ved=0CFIQsAQ&biw=1350&bih=608
Telekinetic
1 / 5 (2) Aug 09, 2012
ValeriaT
1 / 5 (2) Aug 09, 2012
Many World Theory is not a multiverse cosmology in the sense that multiverses can causally reconnect after separation in theory
According to Lee Susskind these two theories are equivalent and I do share this view too. Many worlds are reference frames of quantum fluctuations of vacuum and they're indeed reconnecting too - like the density fluctuations of gas.
Telekinetic
1 / 5 (2) Aug 09, 2012
@aroc91, orac, Karl Kognition, ValeriaT:

You're living proof of MWI!!!
Nikstlitselpmur
1 / 5 (2) Aug 12, 2012
How do we know this isn't frame dragging caused by the black hole at the center of the galaxy? Is there any-place in our solar system that is not effected by the mass at the center even on the quantum level?
Tausch
1.3 / 5 (4) Aug 13, 2012
@TL

...We know... - TL

The arguementation is inconsistence. Assume nothing.
All religion is INaccessible to scientific method.
Let humans have their religions despite science.
dtyarbrough
1 / 5 (3) Sep 01, 2012
Particles always have a position, a linear or orbital direction, a linear or orbital velocity and a rotation direction and rotational velocity as well as gyroscopic precession of the poles in the most extreme cases. The linear or orbital velocity is inversely proportion to the rotational velocity(conservation of momentum). To measure rotational direction requires that you first stop the precession of the poles. Measuring position slows the particle, increases it rotational velocity, increasing it magnetic field to the point that it becomes detectable.

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