Chinese Science vs the NSA
LINK :
http://www.nature.com/news/quantum-communications-leap-out-of-the-lab-1.15093
The Chinese propensity for secrecy is showing up as research to protect data from being recorded by the uninvited .
~~~~~~~~~~~~~~~~
Quantum communications leap out of the lab
China begins work on super-secure network as real-world trial successfully sends quantum keys and data.
Toshiba Research Europe Ltd
Cybersecurity is a step closer to the dream of sending data securely over long distances using quantum physics spurred by two developments.
This week, China will start installing the worlds longest quantum-communications network, which includes a 2,000-kilometre link between Beijing and Shanghai. And a study jointly announced this week by the companies Toshiba, BT and ADVA, with the UK National Physical Laboratory in Teddington, reports encouraging results from a network field trial, suggesting that quantum communications could be feasible on existing fibre-optic infrastructure.
Conventional data-encryption systems rely on the exchange of a secret key in binary 0s and 1s to encrypt and decrypt information. But the security of such a communication channel can be undermined if a hacker eavesdrops on this key during transmission. Quantum communications use a technology called quantum key distribution (QKD), which harnesses the subatomic properties of photons to remove this weakest link of the current system, says Grgoire Ribordy, co-founder and chief executive of ID Quantique, a quantum-cryptography company in Geneva, Switzerland.
The method allows a user to send a pulse of photons that are placed in specific quantum states that characterize the cryptographic key. If anyone tries to intercept the key, the act of eavesdropping intrinsically alters its quantum state alerting users to a security breach. Both the US$100-million Chinese initiative and the system tested in the latest study use QKD.
The Chinese network will not only provide the highest level of protection for government and financial data, but provide a test bed for quantum theories and new technologies, says Jian-Wei Pan, a quantum physicist at the University of Science and Technology of China in Hefei, who is leading the Chinese project.
Pan hopes to test such ideas using the network, along with a quantum satellite that his team plans to launch next year (see Nature 492, 2225; 2012 ). Together, he says, the technologies could perform further tests of fundamental quantum theories over large scales (around 2,000kilometres), such as quantum non-locality, in which changing the quantum state of one particle can influence the state of another even if they are far apart, says Pan.
Sending single photons over long distances is one of the greatest problems in QKD because they tend to get absorbed by optical fibres, making the keys tricky to detect on the receivers end.
This is a big challenge for conventional detectors, says Hoi-Kwong Lo, a quantum physicist at the University of Toronto in Canada. But technological breakthroughs in recent years have significantly reduced the noise level of detectors while increasing their efficiency in detecting photons from just 15% to 50%.
Vast improvements have also been made in the rate at which detectors can count photon pulses crucial in determining the rate at which quantum keys can be sent, and thus the speed of the network. Counting rates have been raised 1,000-fold, to about 2gigahertz, says Lo.
The breakthroughs are pushing the distance over which quantum signals can be sent. Trials using dark fibres optical fibres laid down by telecommunications companies but lying unused have sent quantum signals up to 100kilometres, says Don Hayford, a researcher at Battelle, a technology-development company headquartered in Columbus, Ohio.
To go farther than that, quantum signals must be relayed at node points the quantum networks between Beijing and Shanghai, for instance, will require 32nodes. To transmit photons over longer distances without the use of nodes would require a satellite.
China is not alone in its quantum-communication efforts. A team led by Hayford, together with ID Quantique, has started installing a 650-kilometre link between Battelles headquarters and its offices in Washington DC. The partnership is also planning a network linking major US cities, which could exceed 10,000kilometres, says Hayford, although it has yet to secure funding for that.
The Chinese and US networks will both use dark fibres to send quantum keys. But these fibres are not always available and can be prohibitively expensive, says Andrew Shields, a quantum physicist at Toshiba Research Europe in Cambridge, UK. One way to sidestep the problem is to piggyback the photon streams onto the lit fibres that transmit conventional telecommunications data. However, those conventional data streams are usually about a million times stronger than quantum streams, so the quantum data tend to be drowned out.
The breakthroughs are pushing the distance over which quantum signals can be sent.
In the results announced this week, Shields and his colleagues were successful in achieving the stable and secure transmission of QKDs along a live lit fibre between two stations of the UK telecommunications company BT, 26kilometres apart. The quantum keys were sent over several weeks at a high rate alongside four channels of strong conventional data on the same fibre.
The research builds on previous work in which Shields and his team developed a technique to detect quantum signals sent alongside noisy data in a 90-kilometre fibre, but in controlled laboratory conditions ( K.A. Patel et al. Phys. Rev. X 2, 041010; 2012 ).
Implementing QKD in the real world is much more challenging than in the controlled environment of the lab, due to environmental fluctuations and greater loss in the fibre, says Shields.
The quantum keys in the latest study were sent alongside conventional data travelling at 40gigabits per second. As far as I am aware, this is the highest bandwidth of data that has been multiplexed with QKD to date, add Shields.
He calculates that it would be possible to send QKD signals alongside 40 conventional data channels. Optical fibres usually carry between 40 and 160 telecommunications channels, meaning that quantum communication could be carried out with existing infrastructure.
I find it an impressive piece of work that demonstrates the multiplexing of strong classical signals with quantum signals in the same fibre for the first time in a field trial, says Lo. Removing the need for dark fibres, he says, is an important step in showing that QKD has the potential to be used in real life.
Nature 508 , 441442 (24 April 2014) doi :10.1038/508441aTags
Who is online
134 visitors
Confused ? You have every right to be . Quantum mechanics is one of the most mind blowing concepts there is . The idea of the quantum entanglement of 2 particles and the resulting action at a distance is nearly surreal .
This material was not part of the curriculum when I was in engineering school . They barely covered the Heisenberg Uncertainty Principle which is somewhat related .
That principle states that when attempting to view the status of an electron you can't get its complete status because the act of reading it changes its status .
Likewise the quantum key can't be read without affecting it . And that warns the data transmission system there has been a security breach .
So ... no one is interested in the possibility that it will be the Chinese who end up protecting the public from the snoopings of the NSA ?
Although I just read a long biography of Einstein including physical and mathematical formulae and explanations, there was little of the science/math I could understand. I did get the general gist of the science, and could understand that he sought but could never establish a unified field theory. I could say the same here, in that I understand the result, just not the esoteric science behind it.
Thanks for putting in a showing and not being intimidated . Quantum mechanics is indeed a confusing topic .
I posted this for 2 reasons :
It involved Chinese science which is a force to be reckoned with .
It was the 1st article I've seen to suggest an application for quantum theory other than "qubits" which you covered here :
...
I would be interested in knowing how the data can survive the node transfer process if the act of reading it causes the quantum states to necessarily change. That is, it would seemingly have to go through a process of amplification to keep the signal to noise ratio down to a point where the data can get through. It seems that this amplification (purification?) process would be akin to the reading of the data, thus rendering all data that pass through the node to be deemed as read.
Further, if you know the quantum states that the photons are supposed to be in, there has to be a knowledge of the states (maybe that is where the entanglement comes in) and if you intercepted the message, you would know those states because you have read them...
I would say that the nodes are the weak link in the encryption process, be it regular digital or quantum. But my college is a long way back and I have learned most about quantum mechanics from shows such as science friday and the odd articles that I happen to comes across.
You could easily know more about this topic than I do . All I can do is repeat what was in the article . This is not electronic transmission . It is photon transmission through fiber optics .
Here's a quote from the article which may shed some illumination on the issues :
Its only the key which has this quantum entangled property apparently . Once the key gets transmitted correctly and unintercepted the ordinary data gets encrypted with that key .
This is an excellent point . Node reception and retransmission should interfere with the quantum entanglement one would think . Where the answer lies to that dilemma is outside my knowledge .
As Mr. Spock would say: Fascinating.
We will have to wait and see what comes of this research. I'm not understanding much of it - liberal arts education doesn't cover this stuff.
Thanks for your comment . Perhaps this will be more of use to you [& many of us ] :
Chinese spies read Australian MPs' emails for a year: report
Oddly enough we have all seen the effects of quantum mechanics . The following article details the "quantum dot" :
It has been used for years now to produce monochromatic light at high efficiency . If you own an LED flashlight it uses q-dots to produce UV light which is then converted by phosphors into a brilliant white light .
Wow; how interesting!
What I found most interesting was that is an actual application for quantum entanglement . I was wondering for decades if there would ever be an application for it ... but here it is !