Big scientific breakthrough at sub-atomic level holds promise for secure comms

June 16, 2017
Entangled particles hold the promise of creating a communications system that can send secure messages without cables, signals or code

Chinese scientists have pulled off a major feat with one of the sub-atomic world's weirdest phenomena: photons that behave like twins and experience the same things simultaneously, even over great distances.

The space-based technique developed by the researchers and reported in the journal Science holds potential for revolutionizing telecommunications and perhaps someday developing a hack-proof internet.

The principle is called , in which photons or neutrons are created in such a way that they are linked and behave as if they were one entity, even if they are physically separated.

In a groundbreaking experiment led by Professor Jian-Wei Pan of Hefei University in China, a laser on a satellite orbiting 300 miles above the earth produced entangled photons.

They were then transmitted to two different ground-based stations 750 miles (1,200 kilometers) apart, without breaking the link between the photons, the researchers said.

That distance is 10 times greater than the previous record for entanglement. The experiment also marked the first time were generated in space.

Both stations are in the mountains of Tibet, at a height that reduced the amount of air the fragile photons had to traverse.

"It's a huge, major achievement," Thomas Jennewein, physicist at the University of Waterloo in Canada, told Science. "They started with this bold idea and managed to do it."

Entangled particles hold the promise of creating a communications system that can send secure messages without cables, signals or code: any action on one of the twins is detected by the other, so the message sent along such a conduit can't be hacked.

Those properties of also hold the potential for super-fast computers.

American and European teams are considering sending -based equipment to the International Space Station.

One test would see whether changing gravitational fields affect entanglement.

Scientists would compare photons in the weaker gravitational environment of orbit with entangled partners sent to Earth, says Anton Zeilinger, a physicist at the Austrian Academy of Sciences in Vienna.

"There are not many experiments which test links between gravity and quantum physics," he told Science.

"I'm personally convinced that the internet of the future will be based on these quantum principles."

Explore further: Physicists use quantum memory to demonstrate quantum secure direct communication

More information: J. Yin el al., "Satellite-based entanglement distribution over 1200 kilometers," Science (2017). science.sciencemag.org/cgi/doi/10.1126/science.aan3211

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Eikka
4.3 / 5 (3) Jun 16, 2017
Wouldn't the fragility of the photon pairing also mean it's incredibly easy to just block the entire communication and make it practically useless, merely by attempting to listen in?
Gigel
5 / 5 (1) Jun 16, 2017
I think that is the idea with quantum cryptography: if someone cracks it, then the receiver will know it. It is unsafe if it is cracked without leaving a signature of the cracking, as it can be done for classical cryptography.
StygianAgenda
1 / 5 (1) Jun 16, 2017
Wouldn't the fragility of the photon pairing also mean it's incredibly easy to just block the entire communication and make it practically useless, merely by attempting to listen in?


It's not the pairing that's fragile, but rather the photons themselves. Once the photons are paired, they can be theoretically separated by incredible distances (we're talking light-years-distance here) and remain in binary sync. On the upside, there is no physical link to be hacked, so hacking a quantum-entangled-network connection would be theoretically impossible provided that the entangled pairs are under the complete control of the operators.

Where things get dicey is where further entanglements are concerned --which is something that research should bare out over time. What this would mean is that a determined adversary might find a way to sync a 3rd photon to the other two, creating an effect much like a mirror port on a router.

The bigger problem is bandwidth.
StygianAgenda
3 / 5 (2) Jun 16, 2017
Quantum encryption may turn out to be less useful than it would seem. If a subatomic particle is the element of data-structure, then it has a harmonic frequency that can be matched or disrupted. In the case of entanglement, if a 3rd photon can be paired to the other 2, and this can be scaled, it gives us bandwidth --and also a means to eavesdrop. The connection itself, per pair is 1-bit, or literally 0.000001mbit, meaning that first 300bps modems were 300x faster at this point.
The question then becomes "how do you maintain entangled coherency of a vast quantum array?", which is a very good question. How stable are quantum-entangled particles in mass? Will the combined mass create a distortion effect at the angstrom-scale, generating fields that introduce inaccuracy or outright failure?

The end-stable-results: Once a paired-array is setup at Mars & Earth, it should eliminate the time-delay for communications, because the particles need no transmission medium.
StygianAgenda
1 / 5 (1) Jun 16, 2017
The first place I'd heard of quantum entanglement was the game "Mass Effect 2", where it was used as a communications technology. Apparently the writers were pretty familiar with the theories; though, there were a few things that didn't mesh with reality, mainly in terms of the bandwidth itself --it was basically assumed that the entangled pair had no theoretical bandwidth limitation, but think about it... it's a 1 bit interface, so unless you have a massive array of entangled particles at each end of a connection, then you can't just use a laser to put a pair of particles where you want them and get them chatting at a level that would be useful in any sense beyond academic.

If we can eventually create entangled arrays, we'll still need a means of delivering the nodes to the endpoints where communications are expected to occur. By the time we delivered 1 array to the next star system, we'd have already surpassed the technology, making the device obsolete before ever going online.
Da Schneib
5 / 5 (1) Jun 17, 2017
"Breakthrough" is pretty over the top, I'd say. This was pretty much expected, but definitely needed to be tested; it's solid science, not a revolution.

@Eikka,
merely by attempting to listen in
That's the whole point. This is a key distribution solution. Once you can distribute the key by means of an entanglement channel, you can check whether the key was compromised or not. You don't have to send much key to encrypt a lot of data.

@Stygian,
if a 3rd photon can be paired to the other 2
Not without disrupting one of them. You can create 3 or more entangled photons at the same time, but although you can copy the state of one or more of them later, you can't do so without changing the state of the copied one.

@Stygian,
eliminate the time-delay for communications
No. It can't do this. This channel can't carry information faster; it can only carry more information in the same time. The delay will still be there.
EmceeSquared
5 / 5 (2) Jun 17, 2017
Da Schneib:
@Eikka,
merely by attempting to listen in
That's the whole point. This is a key distribution solution. Once you can distribute the key by means of an entanglement channel, you can check whether the key was compromised or not. You don't have to send much key to encrypt a lot of data.


However, as Eikka is saying, this technique is succeptible to a Denial of Service (DoS) attack on the key distribution phase. If you can never distribute the key, you can't communicate, so the attacker has won something, even if not access to the message. They've stopped the communication. This is a very successful business model. Ransomware, or just forcing comms over an unsecured channel and taking your (bad) chances.
Da Schneib
3.5 / 5 (2) Jun 17, 2017
@Emcee, when someone breaks in on your tight beam you just bounce it off another satellite.

When someone breaks in on your fiber you send armed guards to go take care of it.

The point is, you can detect if they broke in. The attacker has engaged in a minor inconvenience; your goal then is to make it a major problem for them. Nation-states can do that. It's detecting it that's the problem, and this solves that problem.

Do keep asking those questions, though. That was a good one.
EmceeSquared
4.7 / 5 (3) Jun 18, 2017
Da Schneib:
@Emcee, when someone breaks in on your tight beam you just bounce it off another satellite.

When someone breaks in on your fiber you send armed guards to go take care of it.


Well, I think the satellite network narrowcasting across vast spans free space might be susceptible to persistent EM interference, especially if the interference is broadcast with the resources of a largish national government or even a $100B-cap global tech corp. Fiber is much harder to interfere with, but still breaking it is very asymmetric in resources compared to defending it. I expect the transoceanic lines can be disrupted with depth charges, which is hardly subtle but still within the operational capacity of a very large org. Point is that DoS seems possible, even if expensive. At least it's more expensive than, say, today's IOT botnets - but by the same token securing it is even more expensive than public key crypto.
Da Schneib
5 / 5 (1) Jun 18, 2017
Remember that credible long range space communications involve lasers or masers. You have to be right in the beam path to interfere.

And keep in mind that quantum encryption key distribution is as easy as public key distribution. You only have to distribute the key securely; once that's done you can use it to send a symmetric bulk encryption key. This has all been figured out long ago.
PTTG
5 / 5 (2) Jun 18, 2017
You can't use the photons to send messages faster than light, only to ensure that two places generate the same set of random numbers without communicating.
Eikka
1 / 5 (1) Jun 19, 2017
Remember that credible long range space communications involve lasers or masers. You have to be right in the beam path to interfere.


Maybe, but we're on the earth, and it's very difficult here to hit just a single reciever and have no reflections or dispersion along the beam path, especially if you're doing over the horizon communications. Beaming at a satellite necessarily reflects some of the beam back, and vice versa a satellite beaming at you hits a large area of ground because it would be practically impossible to aim at a single point target as the satellite constellation moves.

antialias_physorg
5 / 5 (1) Jun 19, 2017
And keep in mind that quantum encryption key distribution is as easy as public key distribution.

Exactly Once the key is distributed you can transmitthe message through conventional channels. While the message may then be intercepted it cannot be decrypted (unless you used an unsecure encryption algorithm...e.g. one susceptible to being cracked by quantum computers).

Point is that DoS seems possible, even if expensive.

Depends how many such satellites there are. In the end you only need line of sight to one of them (think of GPS. If a few of the GPS satellites fail it doesn't compromise the entire system). If your recipient never acknowledges reception of the key then at least you know someone is trying to interfere.

Of course in an all-out war satellites will get demolished on a grand scale. But then again: that goes for all other lines of communication, too.

klr
5 / 5 (1) Jun 19, 2017
Einstein was right when he did not agree with the EPR experiment conclusions and had said, "spooky action at a distance" cannot occur and that, "God does not play dice". Linear Polarization http://vixra.org/...74v5.pdf
Eikka
1 / 5 (1) Jun 19, 2017
Of course in an all-out war satellites will get demolished on a grand scale. But then again: that goes for all other lines of communication, too.


We don't need to be in an all-out war to have espionage and interruptions.

Every day there are DDoS attacks online to gain some sort of advantage for the offending party. Hackers disrupting communications can mean that e.g stock prices aren't updated in due time and someone makes a huge profit by making a quick transaction in between.
Da Schneib
5 / 5 (1) Jun 19, 2017
but we're on the earth
Space is right up there a hundred miles away.

You trolls tend fo forget that.
EmceeSquared
not rated yet Jun 19, 2017
klr:
Einstein was right when he did not agree with the EPR experiment conclusions and had said, "spooky action at a distance" cannot occur and that, "God does not play dice". Linear Polarization http://vixra.org/...74v5.pdf


Einstein was wrong about that as has now been proven many times conclusively. Scientists are no longer required for creating and using quantum entanglement, only engineers. Also, Einstein was wrong about god, who exists only as a folk story.

BTW, don't bother posting links to vixra.org as if it proves anything. It's not peer-reviewed, and so has as much proof as, say, your post on phys.org . Any valid contents in it are indistinguishable from error, fiction or simple lies.
swordsman
not rated yet Jun 19, 2017
Light waves pass through one another without any effect. That is called "superposition". When two coherent waves pass through one another, apparent interference occurs. However, this is simply the coherent addition and subtraction of these waves, thus creating an apparent "entanglement". When these waves are crossed at angles, they add an attract, producing time variant addition and subtraction. Photons are not particles, as these effects could not occur for particles. Huge amounts of time and effort devoted to nothing except confusion.
antialias_physorg
not rated yet Jun 19, 2017
apparent interference occurs

It's not just 'apparent'. You can set up the double slit experiment with a very weak photon source (i.e. a source that emits photons so infrequently that you can make sure that there is only ever one photon en route between emitter and the detector screen) and you still get interference.

Light waves pass through one another without any effect.

Not always. You can get light to interact (photon-photon coupling). It requires high energies, though, because you need enough for the creation of a positron/electron pair.
https://en.wikipe..._physics
EmceeSquared
not rated yet Jun 19, 2017
swordsman:
Light waves pass through one another without any effect. That is called "superposition".


We are not talking about the superposition of waves. We are talking about the superposition of quantum states.

When two coherent waves pass through one another, apparent interference occurs. However, this is simply the coherent addition and subtraction of these waves,


No, the double slit experiment and others demonstrate light interfering with light. Likewise when light waves at opposite (180 degrees different) phases superpose they cancel each other, as numerous laser demonstrations clearly show.

thus creating an apparent "entanglement".


No, entanglement is the synchronization of the quantum states of physically separated quantum systems so that act as a single quantum system.

Huge amounts of time and effort devoted to nothing except confusion.


Why did you wait until the end of your D- comment to make that disclaimer of its falsehoods?

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