Reviving Einstein's spooky action at a distance

Mar 18, 2014

Physicists at The University of Queensland and the Australian National University (ANU) have demonstrated a software-based quantum amplifier which has the potential to expand the use of ultra-secure quantum cryptographic communications.

The development could lead to new ways to guarantee security of everyday communications, including financial transactions and email.

ANU Research School of Physics and Engineering PhD student Helen Chranowski said this had the potential to guarantee security for any kind of information you want to transmit, from particularly sensitive information, like banking data or electoral results, to personal emails.

Quantum cryptography exploits to guarantee 100 per cent security between a sender and receiver of information.

Most forms of quantum communication also use a phenomenon known as quantum entanglement, which Albert Einstein described as "spooky action at a distance".

Although powerful, this phenomenon is fragile and is often destroyed before it can be transmitted over large distances.

The usual approach to combating loss - an amplifier – such as those used for radio or television signals, only makes the situation worse.

Researchers, led by Professor Ping Koy Lam at the ANU Research School of Physics and Engineering, have used a sophisticated scheme to work out when an amplified signal works or fails.

They have developed an algorithm which allows them to verify whether a quantum entanglement signal has been successfully received.

The software allows the physicists to filter out unwanted signal failures.

It is now possible to use an amplifier to distribute the signals over greater distances, and for the sender and receiver to know if the signal has arrived safely.

Professor Lam said the results showed clear success in resurrecting the quantum effect that so perturbed Einstein.

UQ's Professor Timothy Ralph said the results would help harness the power of quantum entanglement in communications.

"If we want to use entanglement over larger distances, and harness its power for telecommunication, we need quantum amplifiers that allow us to resurrect in a communication line," he said.

The results have been published in the latest on-line issue of Nature Photonics.

Explore further: More secure communications thanks to quantum physics

More information: Measurement-based noiseless linear amplification for quantum communication, Nature Photonics (2014) DOI: 10.1038/nphoton.2014.49

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johanfprins
5 / 5 (1) Mar 19, 2014
Did "quantum entanglement" per se perturb Einstein, or the impossible claim that two separate entities ("particles") can be entangled?

The latter is obviously incorrect since two separate entities cannot form a SINGLE coherent wave.
Whydening Gyre
1 / 5 (1) Mar 19, 2014
Of course it can. Can't have a single wave til you have at least two particles synchronously moving in it.
johanfprins
1 / 5 (1) Mar 20, 2014
Nope! They are not two "particles" when you have a SINGLE wave.:

A laser beam is a single coherent light-wave with parallel wave-fronts. Where are your "particles"?

A photon is just the same: It is the lowest energy coherent wave that a source can emit. This does not mean that a higher energy wave consists of the superposition of SEPARATE photons. It cannot since the energy of a coherent light-wave is continuously distributed within the volume of the wave.
arom
1 / 5 (5) Mar 20, 2014
Most forms of quantum communication also use a phenomenon known as quantum entanglement, which Albert Einstein described as "spooky action at a distance".
…..
Professor Lam said the results showed clear success in resurrecting the quantum effect that so perturbed Einstein.

Actually up to now it seems that there is still no obvious physical evidence about the 'magic' entanglement, and what which seems to support it is the theoretical (mathematical) prove using Bell theorem. Understanding the mechanism of the mysterious quantum mechanics could help to settle the problem….

http://www.vacuum...19〈=en
Whydening Gyre
5 / 5 (1) Mar 20, 2014
Nope! They are not two "particles" when you have a SINGLE wave.:

A laser beam is a single coherent light-wave with parallel wave-fronts. Where are your "particles"? A photon is just the same: It is the lowest energy coherent wave that a source can emit. This does not mean that a higher energy wave consists of the superposition of SEPARATE photons. It cannot since the energy of a coherent light-wave is continuously distributed within the volume of the wave.

Can't have a "team" til there is more than one player on it... Quit complicating a simple situation.
johanfprins
not rated yet Mar 20, 2014
Can't have a "team" til there is more than one player on it... Quit complicating a simple situation.


It is you who are complicating a simple situation by assuming that a laser beam is a "team" of photons. It is not. Both a laser beam and a photon are each a SINGLE coherent wave which has parallel wavefronts. They are both solutions of Maxwell's wave equations and consist of continuously distributed electromagnetic energy. There is no granularity within either one of these waves.
Whydening Gyre
5 / 5 (1) Mar 20, 2014
It is you who are complicating a simple situation by assuming that a laser beam is a "team" of photons. It is not. Both a laser beam and a photon are each a SINGLE coherent wave which has parallel wavefronts. They are both solutions of Maxwell's wave equations and consist of continuously distributed electromagnetic energy. There is no granularity within either one of these waves.

So... you are saying it is just a bigger photon that is now "waving"?
Q-Star
5 / 5 (1) Mar 20, 2014
It is you who are complicating a simple situation by assuming that a laser beam is a "team" of photons. It is not. Both a laser beam and a photon are each a SINGLE coherent wave which has parallel wavefronts. They are both solutions of Maxwell's wave equations and consist of continuously distributed electromagnetic energy. There is no granularity within either one of these waves.

So... you are saying it is just a bigger photon that is now "waving"?


What he is saying is: "I hate particles!!! I get irrational anytime I see the word particle!!!!". If ya don't believe me, just peek at any thread of comments he's taken part in over the last few years.
Whydening Gyre
5 / 5 (3) Mar 20, 2014
So... you are saying it is just a bigger photon that is now "waving"?
What he is saying is: "I hate particles!!! I get irrational anytime I see the word particle!!!!". If ya don't believe me, just peek at any thread of comments he's taken part in over the last few years.

You know, Q, I may even partially think on the same lines as some of these people, but I get so tired of the "I have a TOE that will explain it coming out soon" or "you stupid idiots can't even see the truth" sort of BS.
Means they don't.
Think I might, tho. G.lobally Organized/Ordinated/Oriented (Pick an O, any will do) D.ata.
We're all an AI quantum computer.. housing the combined thoughts of an entire planet, on an excursion of the Universe...
How's THAT for a TOE...?
Q-Star
5 / 5 (2) Mar 20, 2014
How's THAT for a TOE...?


It has more substance than most bandied about here.
Whydening Gyre
5 / 5 (2) Mar 20, 2014
How's THAT for a TOE...?


It has more substance than most bandied about here.

LOL. Thanks....:-)
johanfprins
not rated yet Mar 21, 2014
So... you are saying it is just a bigger photon that is now "waving"?


Yes. A photon is a SINGLE coherent wave that has the lowest energy that a SINGLE coherent wave with that frequency can have. It is impossible for an EM source to emit less energy than the energy of a photon: But it is possible to have an EM-source that can emit SINGLE coherent wave with more energy. Our radio-antennas do this every day.

You can have two separate photon-waves. But you can also have two parts of a SINGLE light wave which remain a SINGLE light wave. The latter happens when a laser beam splits to move simultaneously through two slits, while remaining a SINGLE wave: This also happens when two parts are entangled: They remain a SINGLE wave.

Also when a single photon moves simultaneously through two slits. Since you can only detect a SINGLE photon on the other side, a measurement on the other side destroys the two parts. And thus also the diffraction pattern! This is how waves interact.