# China teleports photon to space ....paves the way for ultra secure 'quantum internet



## CAPSLOCKSTUCK (Jul 12, 2017)

Physicists in China have revealed the details on their ground-breaking experiment to achieve ‘ultra-long-distance quantum teleportation,’ which could pave the way for a global quantum internet.

In a major breakthrough, the team established the first ground-to-satellite quantum network, which allowed them to transmit a photon from an entangled pair up to 870 miles (1,400 kilometers).

Entangled photons theoretically maintain their link across any distance, and have potential to revolutionize secure communications – but, scientists have previously only managed to maintain the bond for about 62 miles (100 km).







The experiments relied on the ‘quantum satellite’ Micius, which launched to a Sun-synchronous orbit last year from the Jiuquan Satellite Launch Centre.

As the satellite moves through its orbit, its distance from the Tibetan ground station varies from 500 km to 1400 km (310.7 – 869.9 miles).

‘In our experiment, the quantum state to be teleported is the polarization of a single photon,’ the researchers explain in the paper, published to arXiv.

‘Such a single qubit is generated from an observatory ground station in Ngari, and aimed to be teleported to the Micius satellite that has been launched from China on 16th August 2016 to an altitude of ~500 km.’

This setup is what’s known as an uplink configuration, according to the researchers.

The 1,300 pound craft satellite is equipped with a laser beam, which the scientists subjected to a beam splitter.

This gave the beam two distinct polarized states.

In the up-link approach, the transmitter is located at the ground station, while the satellite acts as the receiver.







‘To optimize the link efficiency and overcome the atmospheric turbulence in the up-link, a series of techniques are developed,’ the researchers explain, ‘including a compact ultra-bright source of multi-photon entanglement, narrow beam divergence, high-bandwidth and high-accuracy acquiring, pointing, and tracking (APT).’

Not only did the team successfully transmit single-photon qubits over hundreds of miles, from Earth to space, for the first time, but they managed to do it for six input states, to ‘demonstrate that the quantum teleportation is universal.’


The Micius satellite launched from Jiuquan Satellite launch Center last year, and the new findings mark a promising step forward in the two-year mission prove successful, which could be followed by a fleet of others if all goes well, according to Nature.

To overcome the complications of long-distance quantum entanglement, scientists often break the line of transmission up, creating smaller segments that can then repeatedly swap, purify, and store the information along the optical fiber, according to the American Association for the Advancement of Science.

Or, as in this case, they can use lasers and satellites. 


The researchers sought to prove that particles can remain entangled across great distances, aiming for nearly 750 miles.

Earlier efforts to demonstrate quantum communication have shown this can be done up to just over 180 miles, and scientists hope that transmitting the photons through space will push this even farther.


----------



## RejZoR (Jul 12, 2017)

It'll really be interesting when we'll have subspace communications, allowing us and interstellar spacecrafts to communicate with us without any delay. That's gonna be awesome. Imagine controlling Mars rover in real-time without any delay. Or talking to ISS in real-time without any delay. But I guess this is one step closer to that...


----------



## dont whant to set it"' (Jul 12, 2017)

thing is, if one looks, it , the photon in this case might not be there if it ever where.


----------



## DeathtoGnomes (Jul 12, 2017)

Beam me up Scotty!


----------



## Aquinus (Jul 12, 2017)

If the mode of transport is still bound by the speed of light (it's a photon after all,) latency is still going to be as bad as current RF implementations because of the distance that has to be traversed. If this serves to do anything, it's to improve bandwidth over incredibly long distances, not improve latency. You would need something that travels or propagates faster than light relative the transmitter in order to do that.


----------



## Papahyooie (Jul 12, 2017)

Aquinus said:


> If the mode of transport is still bound by the speed of light (it's a photon after all,) latency is still going to be as bad as current RF implementations because of the distance that has to be traversed. If this serves to do anything, it's to improve bandwidth over incredibly long distances, not improve latency. You would need something that travels or propagates faster than light relative the transmitter in order to do that.


 
That's exactly why this is awesome...  It is not bound by the speed of light. It's literally the exchange of information instantaneously. The photon did not physically travel through space. The information regarding the photon's polarization traveled instantaneously, faster than the speed of light. They use the word "teleported" because the entangled photon pair can be thought of as the "same" photon. The information didn't have to travel through space. It's the first "long-distance" transmission of information faster than the speed of light. That's exactly what makes it amazing, and why it has such huge implications.


----------



## Aquinus (Jul 12, 2017)

Papahyooie said:


> The photon did not physically travel through space.


That's why a laser beam was used, right?


CAPSLOCKSTUCK said:


> The 1,300 pound craft satellite is equipped with a laser beam, which the scientists subjected to a beam splitter.
> 
> This gave the beam two distinct polarized states.
> 
> In the up-link approach, the transmitter is located at the ground station, while the satellite acts as the receiver.


That just sounds like optical data transfer but, without the fiber but, a laser implies a stream of photons traveling at the speed of light.


----------



## Papahyooie (Jul 12, 2017)

Aquinus said:


> That's why a laser beam was used, right?



That was only for the setup of the experiment. They had to entangle the photons then get the entangled photons up there by using a laser/beam splitter. Then when they changed the entangled photons' state on the ground, the entangled photons on the satellite were also changed instantaneously (or vice/versa, as it seems in this experiment ). A "qubit" is a single piece of quantum information. The *information* was teleported. And since the entangled photons can be described as a single photon, that's why they say they teleported a photon.


----------



## Papahyooie (Jul 13, 2017)

So this was irking me yesterday, and so I did some more reading on the subject... it turns out that entangled particles cannot send arbitrary information faster than light. The information itself "travels" faster than light, but no arbitrary information can be encoded using this information because interaction with the particles causes decoherence. The act of measuring them means that they will no longer be entangled. I knew this before, but hadn't considered the implications it had on communications. So unfortunately... no FTL communication.


----------



## Divide Overflow (Jul 13, 2017)

Physics is such a tease!


----------



## jboydgolfer (Jul 13, 2017)

the difficult part (one of Many) is keeping the bond over distances of increasing greatness. once solved, this becomes a "feasible" method of information transmission which would certainly cause massive changes in SO many different areas by widening possibilities


----------



## W1zzard (Jul 13, 2017)

Thank god, someone finally checked the facts. Popular online media writes everything related to  "quantum" in the most interesting ways


----------



## Papahyooie (Jul 13, 2017)

jboydgolfer said:


> the difficult part (one of Many) is keeping the bond over distances of increasing greatness. once solved, this becomes a "feasible" method of information transmission which would certainly cause massive changes in SO many different areas by widening possibilities



As I said above, this isn't really true. The only information that can be transmitted via this method is the information regarding the particles themselves. Once the particles are measured, they become disentangled. This means that no further information can be encoded using the state of the photons, because the act of measuring or manipulating the photon causes it to become disentangled with its "partner." The superposition of the photon being in two states (and indeed two places) at once collapses into a single state. Once they have been measured they are no longer entangled, and on top of that, communicating the results requires the use of classical forms of communication (sound, light, whatever) which means that the information regarding the results cannot travel faster than light. If you cannot confirm your results faster than the speed of light, then no arbitrary information can be transmitted. 

Apparently they've already addressed this in quantum physics. It's called the no-communication theorem. Basically, the universe maintains causality by preventing such FTL transmission of information, while still allowing the instantaneous "transmission" of quantum information. With what we know at this time, it is not possible to use quantum entanglement to encode information for instant long-distance transmission. 

https://en.wikipedia.org/wiki/No-communication_theorem


----------



## Vya Domus (Jul 13, 2017)

Sorry to brake it to you all but this is NOT transmitting information at a speed greater than the speed of light , or rather not any useful information.

The only place where I see this useful is for encrypting data transmissions.

I wonder however , how the hell can they manage to detect one photon in particular through so much noise.


----------



## jboydgolfer (Jul 13, 2017)

Papahyooie said:


> As I said above



wasnt arguing its feasibility. i just commented on the hurdles of dealing with maintaining a bond over greater distances.


----------



## Papahyooie (Jul 13, 2017)

Vya Domus said:


> Sorry to brake it to you all but this is NOT transmitting information at a speed greater than the speed of light , or rather not any useful information.
> 
> The only place where I see this useful is for encrypting data transmissions.
> 
> I wonder however , how the hell can they manage to detect one photon in particular through so much noise.


I think that's why it confuses so many people (myself included.) It IS technically transmitting information faster than light... just not arbitrary information. Not any information you'd want to send, or would be useful.


----------



## MrGenius (Jul 13, 2017)

Quantum teleportation is real. It is not a hoax. These are valid scientific experiments that prove it. There's been no miscommunication in stating their results. Only misunderstanding of the basic scientific principles behind them. Quantum teleportation does not violate any laws of physics(ie the speed of light). Nor is it inconsistent with any established theorems(ie no-communication theorem, no-cloning theorem, no-deleting theorem, no-teleportation theorem). Hence it is not a form of instantaneous communication. It is a form quantum information communication that doesn't require the particle possessing quantum information as a qubit to be transported with the qubit to another particle's location for successful transfer of the quantum information to the other particle. The qubit possessed by particle A is transported without particle A, in the form of classical bits of information used to describe said qubit, to particle B's location. Particle B is modified using the information provided by those classical bits to now possess a qubit identical to particle A's. So in essence particle A's quantum information/qubit can be imagined as having been teleported to the location of particle B. Since particle B now possesses an identical copy of the quantum information, in the form of a qubit, previously possessed by particle A. And particle A no longer possesses the qubit sent to particle B since the measurement required to obtain the classical bits of information about it changed its quantum state.

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

It's really not that complicated to understand. Yeah right. It actually is very confusing if worded in certain ways.


----------



## Komshija (Jul 14, 2017)

RejZoR said:


> It'll really be interesting when we'll have subspace communications, allowing us and interstellar spacecrafts to communicate with us without any delay. That's gonna be awesome. Imagine controlling Mars rover in real-time without any delay. Or talking to ISS in real-time without any delay. But I guess this is one step closer to that...


 That won't happen anytime soon. FTL communication would require bending of space and time and possibly violating special relativity, meaning that we would have to change few laws of physics.


----------



## DeathtoGnomes (Jul 14, 2017)

the laws of physics are only limited by mans own limitation of thought and ability to prove them. Limit how deep and how far you can think that is acceptable by your peers, and you will go no further. Accept there are no limitations and you find you are limited by the tools available to prove how far you can push those limitations.


----------



## Papahyooie (Jul 14, 2017)

MrGenius said:


> Quantum teleportation is real. It is not a hoax. These are valid scientific experiments that prove it. There's been no miscommunication in stating their results. Only misunderstanding of the basic scientific principles behind them. Quantum teleportation does not violate any laws of physics(ie the speed of light). Nor is it inconsistent with any established theorems(ie no-communication theorem, no-cloning theorem, no-deleting theorem, no-teleportation theorem). Hence it is not a form of instantaneous communication. It is a form quantum information communication that doesn't require the particle possessing quantum information as a qubit to be transported with the qubit to another particle's location for successful transfer of the quantum information to the other particle. The qubit possessed by particle A is transported without particle A, in the form of classical bits of information used to describe said qubit, to particle B's location. Particle B is modified using the information provided by those classical bits to now possess a qubit identical to particle A's. So in essence particle A's quantum information/qubit can be imagined as having been teleported to the location of particle B. Since particle B now possesses an identical copy of the quantum information, in the form of a qubit, previously possessed by particle A. And particle A no longer possesses the qubit sent to particle B since the measurement required to obtain the classical bits of information about it changed its quantum state.
> 
> https://en.wikipedia.org/wiki/Quantum_teleportation
> 
> It's really not that complicated to understand. Yeah right. It actually is very confusing if worded in certain ways.



I don't think anybody here thinks it a hoax. Just a misunderstanding of the wording used. As you said, it is very confusing if worded in certain ways. And if you're not familiar with these established theorems (as i wasn't familiar with the no-communication theorem in particular before yesterday) then it is very easy to assume that the teleportation of quantum information can be extrapolated to mean the possibility of teleporting arbitrary information through encoding. Add to that the general misunderstanding of what a quantum particle even IS, and the fact that teleporting a qubit is analogous to teleporting a particle, and you've got a big recipe for misunderstanding.


----------



## jboydgolfer (Jul 14, 2017)

Never mind a complex theorem, many people have difficulty understanding the bond maintained by entangled photons on its own.


----------



## qubit (Jul 14, 2017)

CAPSLOCKSTUCK said:


> In a major breakthrough, the team established the first ground-to-satellite quantum network, which allowed them to transmit a CAPSLOCKSTUCK from an entangled pair up to 870 miles (1,400 kilometers).


Wicked.


----------



## CAPSLOCKSTUCK (Aug 11, 2017)

China has sent an 'unbreakable' code from a satellite to the Earth, marking the first time space-to-ground quantum key distribution technology has been realised, state media said on Thursday.

China launched the world's first quantum satellite last August, to help establish 'hack proof' communications, a development the Pentagon has called a 'notable advance'.

The official Xinhua news agency said the latest experiment was published in the journal Nature on Thursday, where reviewers called it a 'milestone'.


The satellite sent quantum keys to ground stations in China between 645 km (400 miles) and 1,200 km (745 miles) away at a transmission rate up to 20 orders of magnitude more efficient than an optical fibre, Xinhua cited Pan Jianwei, lead scientist on the experiment from the state-run Chinese Academy of Sciences, as saying.

'That, for instance, can meet the demand of making an absolute safe phone call or transmitting a large amount of bank data,' Pan said.

Any attempt to eavesdrop on the quantum channel would introduce detectable disturbances to the system, Pan said.

'Once intercepted or measured, the quantum state of the key will change, and the information being intercepted will self-destruct,' Xinhua said.


The team established the first ground-to-satellite quantum network, which allowed them to transmit a photon from an entangled pair up to 870 miles (1,400 kilometers).

Entangled photons theoretically maintain their link across any distance, and have potential to revolutionize secure communications – but, scientists have previously only managed to maintain the bond for about 62 miles (100 km). 

The experiments relied on the ‘quantum satellite’ Micius, which launched to a Sun-synchronous orbit last year from the Jiuquan Satellite Launch Centre.

As the satellite moves through its orbit, its distance from the Tibetan ground station varies from 500 km to 1400 km (310.7 – 869.9 miles).

‘In our experiment, the quantum state to be teleported is the polarization of a single photon,’ the researchers explain in the paper, published to arXiv.


https://phys.org/news/2017-08-chinese-team-quantum-keys-ground.html


----------



## CAPSLOCKSTUCK (Sep 30, 2017)

China has held the world's first quantum intercontinental video conference between laboratories in Beijing and Vienna.

The call was held using a new world first space-ground quantum communication network that experts say could revolutionise how humans connect.

The call was held between President Chunli Bai of Beijing's Chinese Academy of Sciences and President Anton Zeilinger of Vienna's Austria Academy of Sciences. 

The Chinese science academy said the encrypted communication system was being trialled for potential 'real-world applications by government, banks, securities and insurance companies'.

There are plans to carry out similar test conversations between someone in China and four other places, Singapore, Italy, Germany and Russia.

Technical reasons had previously limited such conversations to distances of a few hundred kilometres, the academy said, but they had found a 'promising solution to this problem' involving a 'sophisticated satellite, named Micius'.
https://en.wikipedia.org/wiki/Quantum_Experiments_at_Space_Scale

It is equipped with 'a decoy-state QKD transmitter, an entangled-photon source, and a quantum teleportation receiver and analyser'. 


Five ground stations have also been built in China and Tibet.

Earlier this year scientists in China successfully transmitted entangled photons farther than ever before, achieving a distance of up to 1,400 kilometers (870 miles) between suborbital space and Earth.

Using the same 'quantum satellite' Micius, the scientists were able to to transmit a photon from an entangled pair from the ground station in Tibet to the orbiting craft, in what's known as an uplink configuration.


The 1,300 pound craft satellite is equipped with a laser beam, which the scientists subjected to a beam splitter.

This gave the beam two distinct polarized states. 

In the uplink approach, the transmitter is located at the ground station, while the satellite acts as the receiver.

Not only did the team successfully transmit single-photon qubits over hundreds of miles for the first time, but they managed to do it for six input states, to 'demonstrate that the quantum teleportation is universal.'


----------



## StrayKAT (Oct 1, 2017)

China reaches quantum potential, but still will censor the info because of politics


----------

