China Quantum Communiations Technology: Cryptography, Radar, Satellite, Teleportation, Network

[Bussard Ramjet]

Just one thing here, in the triumphalism of the whole thing lets not forget that nothing is "unhackable." Though yes the laws of physics say that superposition caused by observing photons destroy their quantum states, their are many ways to work around.

This is already an established field called Quantum Hacking. I will just give some details here.


The Next Battleground In The War Against Quantum Hacking

Ever since the first hack of a commercial quantum cryptography device, security specialists have been fighting back. Here’s an update on the battle.

Quantum hacking is the latest fear in the world of information security. Not so long ago, physicists were claiming that they could send information with perfect security using a technique known as quantum key distribution.

This uses the laws of quantum mechanics to guarantee perfectly secure communication. And perfectly secure communication is what you get, at least in theory.

The trouble is that in practice the equipment used to carry out quantum key distribution has a number of weaknesses that an eavesdropper can exploit to gain information about the messages being sent. Various groups have demonstrated how quantum hacking presents a real threat to “perfectly secure” communication.

So in the cat and mouse game of information security, physicists have been fighting back by designing equipment that is more secure. Today, Nitin Jain at the Max Planck Institute for the Science of Light in Erlangen, Germany, and a few pals show how the changes still leave the equipment open to attack but at the same time reveal how the next generation of quantum cryptography could be made better.

In quantum key distribution, Alice sends information to Bob encoded in the polarisation of single photons. So she might send a sequence of 0s and 1s as a series of photons polarised horizontally and vertically. Bob can then use this information as the key to a one-time pad for sending information with perfect security. Hence the name quantum key distribution.

An eavesdropper, Eve, can only see the information Alice sends if she knows the directions that correspond to vertical and horizontal. Physicists call this the base of the system.

Without knowing the base, the information the photons carry will seem random. So a key part of the security of quantum key distribution comes from keeping Alice’s base secret.

Just over 10 years ago, hackers found a way for Eve to discover Alice’s base. All Eve has to do is shine a light into Alice’s equipment and measure the polarisation of the reflected photons. These will have bounced off the optical components that determine Alice’s base and so will be polarised in the same way. That gives Eve the crucial information she needs to decode the transmissions without Alice being any the wiser.

Various teams have shown how this approach can hack commercially available quantum cryptography devices, revealing that the claim of perfect security is somewhat overblown.

But the physicists have fought back. One way to stop these kinds of attack is to include a device called an isolator that allows light to travel in one direction but not the other. So Alice can transmit her photons out of the equipment but Eve cannot send photons into it.

The work that Jain and co have done it to study the optical properties of these devices to see just how secure they are. These guys have tested the optical properties of a number of components used in quantum key distribution, including isolators.

The tests have been straightforward. They send a number of photons towards the device and measure the number that pass through. But crucially, they have done this at a number of different wavelengths between 1000 and 1700 nanometres.

The results are revealing. Telecommunication transmission use wavelengths of around 1550 nanometres. And the isolators Jain and co have measured work well at this wavelength.

But these devices are not so good at other wavelengths. “Even high performance isolators do not have high isolation in other wavelength regions, such as from 1300 to 1400 nanometres, where Eve can easily obtain both laser sources,” they say.

In other words, Eve can still discover Alice’s base using lasers of a different colour.

That will be a worrying discovery for organisations now using quantum key distribution to protect their data, not to mention the companies that sell commercial quantum key distribution equipment.

But all is not lost, say Jain and co. There are still more countermeasures that can protect quantum key distribution from Eve’s attacks at other wavelengths. Instead of using a passive device like an isolator, Alice could use an active device that measures incoming photons in the hope of spotting Eve in action. “If Alice contains a monitoring detector in addition to the isolator, then it would become fairly challenging for Eve to simultaneously circumvent both of these countermeasures,” say Jain and co.

Theorists can help here too. The laws of quantum mechanics guarantee the secrecy of a message provided that the amount of information that leaks out is below some threshold, determined by the specific details of the protocol being used..

In these kinds of attacks, Eve’s gains only a certain amount of information about the secret key. If she gets more than this threshold, she can begin to decrypt any secret messages encoded with it.

The theorists can help here by determining how much information Eve might get from her attacks and raising the threshold accordingly. That increases the security of the system but also makes it considerably slower to send data.

That is an interesting piece of work. Information security specialists have always indulged in a cat and mouse war against attackers. For a short time, these specialists had hoped that quantum key distribution would be the ultimate weapon to bring this war to an end. That hope now looks somewhat premature.

The Next Battleground In The War Against Quantum Hacking | MIT Technology Review

 

[cirr]

Huawei, China Unicom commercially deploy tiny Atom Router

February 3, 2015 | By Monica Alleven

Huawei and China Unicom Guangdong Branch (Guangdong Unicom) say they've deployed the world's first Atom Router for commercial use.


Atom Router (Image source: Huawei)

Unveiled last year at the Mobile World Congress (MWC) trade show in Barcelona, Spain, the finger-sized router is believed to be the world's tiniest, but it packs a punch.

For starters, it delivers smarter pipes to facilitate network operation and maintenance (O&M) and service innovation, according to the vendor. By providing visible service performance, real-time service level agreement (SLA) measuring and accurate SLA reporting, and quick fault location capabilities, the router enables service-aware network O&M.

The router also promises to allow smooth network evolution, such as an upgrade from GSM/UMTS to LTE/LTE-Advanced backhaul networks, from IPv4 to IPv6 networks and from traditional DCs to future-ready DCs. In addition, software-defined network-enabled Atom Routers allows operators to develop and provision service applications as required for on-demand network deployment.

Guangdong Unicom's deployment, which uses the Huawei Intelligent Perception solution, will help Guangdong Unicom build "industry-leading bearer networks" to deliver optimized mobile service experiences to users, according to the press release.

Guangdong Unicom developed the concept of the "optimal user experience" with a focus on building bearer networks that streamline user services in an E2E manner and are critical to the user experience, but faced challenges related to a lack of basic data, network perception tools and evaluation systems.

To address those challenges, Huawei and Guangdong Unicom embarked on a joint project last June to deploy Huawei's SmartSense solution with the Atom Router. The E2E solution features benefits such as the ability to monitor service quality, including measuring packet loss rate and delay of end-to-end service packets transmitted on an IP network to determine network performance.

The "traffic snapshot" technology identifies and records instantaneous second-grade traffic peaks in real-time to assist in precise network planning, while anti-congestion technology is used to counter the congestion, packet loss and jitter caused by bursty traffic.

Huawei, China Unicom commercially deploy tiny Atom Router - FierceWirelessTech

 

[esolve]

China's bank ICBC Beijing Branch successfully used the quantum communication technology in the intra-city encryption transmission of its electronic archive. It is the first successful application of quantum technology in the Chinese banking industry, marking a new level of information security technology in China’s banking sector.

According to an official with ICBC, to further enhance information security, ICBC has implemented “Beijing-Shanghai Verification and Application Demonstration Project of Quantum Encrypted Communication Technology” together with the University of Science and Technology of China. Meanwhile, the Bank has launched financial application of the quantum technology in intra-city communication of Beijing and Shanghai as well as the thousand-km-level communication between the two cities.

Quantum is a status of microscopic particle. Data information composed of quantum dots is free from external interception or copying during transmission. Quantum communication is by far the only strictly testified technology that can guarantee the unconditional communication security from its principle. It has significant application value and prospect in various fields such as national defense and financial information security, and is regarded as an important technology foundation for safeguarding communication security in future information society. China has a leading position in the world in terms of quantum communication with a sizable experiment network of quantum communication. The “Beijing-Shanghai Verification and Application Demonstration Project of Quantum Encrypted Communication Technology” has been officially launched, with the aim to build a Beijing-Shanghai quantum communication route of over 2,000 km connecting Beijing, Jinan, Hefei and Shanghai as well as a metropolitan access network, which can serve the confidential transmission of governmental information and financial business information.

 

[cirr]

Two quantum properties teleported together for first time

Feb 27, 2015

Two quantum properties teleported together for first time - physicsworld.com

Twice the fun: teleporting two properties of a photon

The values of two inherent properties of one photon – its spin and its orbital angular momentum – have been transferred via quantum teleportation onto another photon for the first time by physicists in China. Previous experiments have managed to teleport a single property, but scaling that up to two properties proved to be a difficult task, which has only now been achieved. The team's work is a crucial step forward in improving our understanding of the fundamentals of quantum mechanics and the result could also play an important role in the development of quantum communications and quantum computers.

Alice and Bob

Quantum teleportation first appeared in the early 1990s after four researchers, including Charles Bennett of IBM in New York, developed a basic quantum teleportation protocol. To successfully teleport a quantum state, you must make a precise initial measurement of a system, transmit the measurement information to a receiving destination and then reconstruct a perfect copy of the original state. The "no-cloning" theorem of quantum mechanics dictates that it is impossible to make a perfect copy of a quantum particle. But researchers found a way around this via teleportation, which allows a flawless copy of a property of a particle to be made. This occurs thanks to what is ultimately a complete transfer (rather than an actual copy) of the property onto another particle such that the first particle loses all of the properties that are teleported.

The protocol has an observer, Alice, send information about an unknown quantum state (or property) to another observer, Bob, via the exchange of classical information. Both Alice and Bob are first given one half of an additional pair of entangled particles that act as the "quantum channel" via which the teleportation will ultimately take place. Alice would then interact the unknown quantum state with her half of the entangled particle, measure the combined quantum state and send the result through a classical channel to Bob. The act of the measurement itself alters the state of Bob's half of the entangled pair and this, combined with the result of Alice's measurement, allows Bob to reconstruct the unknown quantum state. The first experimentation teleportation of the spin (or polarization) of a photon took place in 1997. Since then, the states of atomic spins, coherent light fields, nuclear spins and trapped ions have all been teleported.

But any quantum particle has more than one given state or property – they possess various "degrees of freedom", many of which are related. Even the simple photon has various properties such as frequency, momentum, spin and orbital angular momentum (OAM), which are inherently linked.

More than one

Teleporting more than one state simultaneously is essential to fully describe a quantum particle and achieving this would be a tentative step towards teleporting something larger than a quantum particle, which could be very useful in the exchange of quantum information. Now, Chaoyang Lu and Jian-Wei Pan, along with colleagues at the University of Science and Technology of China in Hefei, have taken the first step in simultaneously teleporting multiple properties of a single photon.

In the experiment, the team teleports the composite quantum states of a single photon encoded in both its spin and OAM. To transfer the two properties requires not only an extra entangled set of particles (the quantum channel), but a "hyper-entangled" set – where the two particles are simultaneously entangled in both their spin and their OAM. The researchers shine a strong ultraviolet pulsed laser on three nonlinear crystals to generate three entangled pairs of photons – one pair is hyper-entangled and is used as the "quantum channel", a second entangled pair is used to carry out an intermediate "non-destructive" measurement, while the third pair is used to prepare the two-property state of a single photon that will eventually be teleported.

Tricky protocol: comparative measurements and teleportation

The image above represents Pan's double-teleportation protocol – A is the single photon whose spin and OAM will eventually be teleported to C (one half of the hyper-entangled quantum channel). This occurs via the other particle in the channel – B. As B and C are hyper-entangled, we know that their spin and OAM are strongly correlated, but we do not actually know what their values are – i.e. whether they are horizontally, vertically or orthogonally polarized. So to actually transfer A's polarization and OAM onto C, the researchers make a "comparative measurements" (referred to as CM-P and CM-OAM in the image) with B. In other words, instead of revealing B's properties, they detect how A's polarization and OAM differ from B. If the difference is zero, we can tell that A and B have the same polarization or OAM, and since B and C are correlated, that C now has the same properties that A had before the comparison measurement.

On the other hand, if the comparative measurement showed that A's polarization as compared with B differed by 90° (i.e. A and B are orthogonally polarized), then we would rotate C's field by 90° with respect to that of A to make a perfect transfer once more. Simply put, making two comparative measurements, followed by a well-defined rotation of the still-unknown polarization or OAM, would allow us to teleport A's properties to C.

Perfect protocol

One of the most challenging steps for the researchers was to link together the two comparative measurements. Referring to the "joint measurements" box in the image above, we begin with the comparative measurement of A and B's polarization (CM-P). From here, either one of three scenarios can take place – one photon travels along path 1 to the middle box (labelled "non-destructive photon-number measurement"); no photons enter the middle box along path 1; or two single photons enter the middle box along path 1.

The middle box itself contains the second set of entangled photons mentioned previously (not shown in figure) and one of these two entangled photons is jointly measured with the incoming photons from path 1. But the researcher's condition is that if either no photons or two photons enter the middle box via path 1, then the measurement would fail. Indeed, what the middle box ultimately shows is that exactly one photon existed in path 1, and so exactly one photon existed in path 2, given that two photons (A and B) entered CM-P. To show that indeed one photon existed in path two required the third and final set of entangled photons in the CP-OAM box (not shown), where the OAM's of A and B undergo a comparative measurement.

The measurements ultimately result in the transfer or teleportation of A's properties onto C – although it may require rotating C's (as yet unknown) polarization and OAM depending on the outcomes of the comparative measurements, but the researchers did not actually implement the rotations in their current experiment. The team's work has been published in the journal Nature this week. Pan tells physicsworld.com that the team verified that "the teleportation works for both spin-orbit product state and hybrid entangled state, achieving an overall fidelity that well exceeds the classical limit". He says that these "methods can, in principle, be generalized to more [properties], for instance, involving the photon's momentum, time and frequency".

Verification verdicts

Physicist Wolfgang Tittel from the University of Calgary, who was not involved in the current work (but wrote an accompanying "News and Views" article in Nature) explains that the team verified that the teleportation had indeed occurred by measuring the properties of C after the teleportation. "Of course, the no-cloning theorem does not allow them to do this perfectly. But it is possible to repeat the teleportation of the properties of photon A, prepared every time in the same way, many times. Making measurements on photon C (one per repetition) allows reconstructing its properties." He points out that although the rotations were not ultimately implemented by the researchers, they found that "the properties of C differed from those of A almost exactly by the amount predicted by the outcomes of the comparative measurements. They repeated this large number of measurements for different preparations of A, always finding the properties of C close to those expected. This suffices to claim quantum teleportation".

While it is technically possible to extend Pan's method to teleport more than two properties simultaneously, this is increasingly difficult because the probability of a successful comparative measurement decreases with each added property. "I think with the scheme demonstrated by [the researchers], the limit is three properties. But this does not mean that other approaches, either other schemes based on photons, or approaches using other particles (e.g. trapped ions), can't do better," says Tittel.

Pan says that to teleport three properties, their scheme "needs the experimental ability to control 10 photons. So far, our record is eight photon entanglement. We are currently working on two parallel lines to get more photon entanglement." Indeed, he says that the team's next goal is to experimentally create "the largest hyper-entangled state so far: a six-photon 18-qubit Schrödinger cat state, entangled in three degrees-of-freedom, polarization, orbital angular momentum, and spatial mode. To do this would provide us with an advanced platform for quantum communication and computation protocols".

Say hello to scalable quantum computation and quantum network technology

The work is published in Nature.

 

[TaiShang]

The values of two inherent properties of one photon – its spin and its orbital angular momentum – have been transferred via quantum teleportation onto another photon for the first time by physicists in China. Previous experiments have managed to teleport a single property, but scaling that up to two properties proved to be a difficult task, which has only now been achieved. The team’s work is a crucial step forward in improving our understanding of the fundamentals of quantum mechanics and the result could also play an important role in the development of quantum communications and quantum computers.

Quantum teleportation first appeared in the early 1990s after four researchers, including Charles Bennett of IBM in New York, developed a basic quantum teleportation protocol. To successfully teleport a quantum state, you must make a precise initial measurement of a system, transmit the measurement information to a receiving destination and then reconstruct a perfect copy of the original state. The “no-cloning” theorem of quantum mechanics dictates that it is impossible to make a perfect copy of a quantum particle. But researchers found a way around this via teleportation, which allows a flawless copy of a property of a particle to be made. This occurs thanks to what is ultimately a complete transfer (rather than an actual copy) of the property onto another particle such that the first particle loses all of the properties that are teleported.

The protocol has an observer, Alice, send information about an unknown quantum state (or property) to another observer, Bob, via the exchange of classical information. Both Alice and Bob are first given one half of an additional pair of entangled particles that act as the “quantum channel” via which the teleportation will ultimately take place. Alice would then interact the unknown quantum state with her half of the entangled particle, measure the combined quantum state and send the result through a classical channel to Bob. The act of the measurement itself alters the state of Bob’s half of the entangled pair and this, combined with the result of Alice’s measurement, allows Bob to reconstruct the unknown quantum state. The first experimentation teleportation of the spin (or polarization) of a photon took place in 1997. Since then, the states of atomic spins, coherent light fields, nuclear spins and trapped ions have all been teleported.

But any quantum particle has more than one given state or property – they possess various “degrees of freedom”, many of which are related. Even the simple photon has various properties such as frequency, momentum, spin and orbital angular momentum (OAM), which are inherently linked.

Teleporting more than one state simultaneously is essential to fully describe a quantum particle and achieving this would be a tentative step towards teleporting something larger than a quantum particle, which could be very useful in the exchange of quantum information. Now, Chaoyang Lu and Jian-Wei Pan, along with colleagues at the University of Science and Technology of China in Hefei, have taken the first step in simultaneously teleporting multiple properties of a single photon.

In the experiment, the team teleports the composite quantum states of a single photon encoded in both its spin and OAM. To transfer the two properties requires not only an extra entangled set of particles (the quantum channel), but a “hyper-entangled” set – where the two particles are simultaneously entangled in both their spin and their OAM. The researchers shine a strong ultraviolet pulsed laser on three nonlinear crystals to generate three entangled pairs of photons – one pair is hyper-entangled and is used as the “quantum channel”, a second entangled pair is used to carry out an intermediate “non-destructive” measurement, while the third pair is used to prepare the two-property state of a single photon that will eventually be teleported.


This schematic shows exactly how the polarization and the OAM was teleported via the comparative measurements and an intermediate non-destructive step. (Courtesy: Nature 518 516/Wang et al.)

The image above represents Pan’s double-teleportation protocol – A is the single photon whose spin and OAM will eventually be teleported to C (one half of the hyper-entangled quantum channel). This occurs via the other particle in the channel B. As B and C are hyper-entangled, we know that their spin and OAM are strongly correlated, but we do not actually know what their values are – i.e. whether they are horizontally, vertically or orthogonally polarized. So to actually transfer A’s polarization and OAM onto C, the researchers make a “comparative measurements” (referred to as CM-P and CM-OAM in the image) with B. In other words, instead of revealing B’s properties, they detect how A’s polarization and OAM differ from B. If the difference is zero, we can tell that A and B have the same polarization or OAM, and since B and C are correlated, that C now has the same properties that A had before the comparison measurement.

On the other hand, if the comparative measurement showed that A’s polarization as compared with B differed by 90° (i.e. A and B are orthogonally polarized), then we would rotate C’s field by 90° with respect to that of A to make a perfect transfer once more. Simply put, making two comparative measurements, followed by a well-defined rotation of the still-unknown polarization or OAM, would allow us to teleport A’s properties to C.

One of the most challenging steps for the researchers was to link together the two comparative measurements. Referring to the “joint measurements” box in the image above, we begin with the comparative measurement of A and B’s polarization (CM-P). From here, either one of three scenarios can take place – one photon travels along path 1 to the middle box (labelled “non-destructive photon-number measurement”); no photons enter the middle box along path 1; or two single photons enter the middle box along path 1.

The middle box itself contains the second set of entangled photons mentioned previously (not shown in figure) and one of these two entangled photons is jointly measured with the incoming photons from path 1. But the researcher’s condition is that if either no photons or two photons enter the middle box via path 1, then the measurement would fail. Indeed, what the middle box ultimately shows is that exactly one photon existed in path 1, and so exactly one photon existed in path 2, given that two photons (A and B) entered CM-P. To show that indeed one photon existed in path two required the third and final set of entangled photons in the CP-OAM box (not shown), where the OAM’s of A and B undergo a comparative measurement.

The measurements ultimately result in the transfer or teleportation of A’s properties onto C – although it may require rotating C’s (as yet unknown) polarization and OAM depending on the outcomes of the comparative measurements, but the researchers did not actually implement the rotations in their current experiment. The team’s work has been published in the journal Nature this week. Pan tells physicsworld.com that the team verified that “the teleportation works for both spin-orbit product state and hybrid entangled state, achieving an overall fidelity that well exceeds the classical limit”. He says that these “methods can, in principle, be generalized to more [properties], for instance, involving the photon’s momentum, time and frequency”.

Physicist Wolfgang Tittel from the University of Calgary, who was not involved in the current work (but wrote an accompanying “News and Views” article in Nature) explains that the team verified that the teleportation had indeed occurred by measuring the properties of C after the teleportation. “Of course, the no-cloning theorem does not allow them to do this perfectly. But it is possible to repeat the teleportation of the properties of photon A, prepared every time in the same way, many times. Making measurements on photon C (one per repetition) allows reconstructing its properties.” He points out that although the rotations were not ultimately implemented by the researchers, they found that “the properties of C differed from those of A almost exactly by the amount predicted by the outcomes of the comparative measurements. They repeated this large number of measurements for different preparations of A, always finding the properties of C close to those expected. This suffices to claim quantum teleportation”.

While it is technically possible to extend Pan’s method to teleport more than two properties simultaneously, this is increasingly difficult because the probability of a successful comparative measurement decreases with each added property. “I think with the scheme demonstrated by [the researchers], the limit is three properties. But this does not mean that other approaches, either other schemes based on photons, or approaches using other particles (e.g. trapped ions), can’t do better,” says Tittel.

Pan says that to teleport three properties, their scheme “needs the experimental ability to control 10 photons. So far, our record is eight photon entanglement. We are currently working on two parallel lines to get more photon entanglement.” Indeed, he says that the team’s next goal is to experimentally create “the largest hyper-entangled state so far: a six-photon 18-qubit Schrödinger cat state, entangled in three degrees-of-freedom, polarization, orbital angular momentum, and spatial mode. To do this would provide us with an advanced platform for quantum communication and computation protocols”.

The work is published in Nature. Reposted from PhysicsWorld.com

 

[Kiss_of_the_Dragon]

When will i able to do this, hope I can get away in one piece

 

[TimeTraveller]

Nice and Amazing.........

 

[cirr]

@TaiShang Perhaps you would care to open up the following thread:

Reserachers in China make breakthroughs in space technology ...

 

[powastick]

When will i able to do this, hope I can get away in one piece

Doesn't work that way though. Quantum teleportation is a bad name and I'm quite confuse myself .

 

[55100864]

The article that published in nature

 

[SelfServeFive]

We can teleport our photon torpedo directly on to the Gerald Ford's bridge.

 

[AndrewJin]

The article that published in nature

The article that published in nature

Too many terms in this paper. That's a problem with English, English terminology is a barrier between experts and the ordinary. They call Department of Cardiology rather than Department of Heart.

 

[55100864]

Too many terms in this paper. That's a problem with English, English terminology is a barrier between experts and the ordinary. They call Department of Cardiology rather than Department of Heart.

That article is like "WTF" to me

 

[AndrewJin]

That article is like "WTF" to me

If it is translated into Chinese, I'll read. Terminology barrier in English makes the tendency of anti-intellectualism in the west even more popular. Every now and then they invent a new word from nowhere, but in Chinese we use existing characters to combine as a new word which makes sense to the ordinary people.

 

[TaiShang]

@TaiShang Perhaps you would care to open up the following thread:

Reserachers in China make breakthroughs in space technology ...

But I cannot see the story.

I am not sure this has been shared somewhere:

Huawei Leads in Applications for Patents Globally
2015-03-20

File photo of Huawei [Photo: baidu]

China's leading telecom solutions provider Huawei has become the world's No. 1 applicant for global patents in 2014.

According to the United Nations agency, Huawei, with nearly 3500 published applications, overtook Panasonic of Japan as the largest applicant of last year.

U.S.-based Qualcomm was the second largest applicant with 2400 published applications, while China's ZTE took third place.

Insiders say the report is partially viewed as a rough barometer of a country's technological progress, and noted that China was the only country to see double-digit growth in its filings.

In recent years, China's top policy-makers have offered incentives to nudge Chinese companies to shift from low-value, low-cost manufacturing to fostering innovation.