Mid-morning. Doug sent you an article from “Science Now” this morning.
** **
Science Now
Physicists Create First Long-Distance Quantum Link
by Jim Heirbaut on 11 April 2012, 5:31 PM
For more than a decade, physicists have been developing quantum mechanical methods to pass secret messages without fear that they could be intercepted. But they still haven't created a true quantum network—the fully quantum-mechanical analog to an ordinary telecommunications network in which an uncrackable connection can be forged between any two stations or "nodes" in a network. Now, a team of researchers in Germany has built the first true quantum link using two widely separate atoms. A complete network could be constructed by combining many such links, the researchers say.
"These results are a remarkable achievement", says Andrew Shields, applied physicist and assistant managing director at Toshiba Research Europe Ltd. in Cambridge, U.K., who was not involved in the work. "In the past we have built networks that can communicate quantum information, but convert it into classical form at the network switching points. [The researchers] report preliminary experiments towards forming a network in which the information remains in quantum form."
Quantum communications schemes generally take advantage of the fact that, according to quantum theory, it's impossible to measure the condition or "state" of a quantum particle without disturbing the particle. For example, suppose Alice wants to send Bob a secret message. She can do the encrypting in a traditional way, by writing out the message in the form of a long binary number and zippering it together in a certain mathematical way with a "key," another long stream of random 0s and 1s. Bob can then use the same key to unscramble the message.
But first, Alice must send Bob the key without letting anybody else see it. She can do that if she encodes the key in single particles of light, or photons. Details vary, but schemes generally exploit the fact that an eavesdropper, Eve, cannot measure the individual photons without altering their state in some way that Alice and Bob can detect by comparing notes before Alice encodes and sends her message. Such "quantum key distribution" has already been demonstrated in networks, such as a large six-node network in Vienna in 2008, and various companies offer quantum key distribution devices.
Such schemes suffer a significant limitation, however. Although the key is passed from node to node in a quantum fashion, it must be read out and regenerated at each node in the network, leaving the nodes vulnerable to hacking. So physicists would like to make the nodes of the network themselves fully quantum mechanical—say, by forming them out of individual atoms.
According to quantum mechanics, an atom can have only certain discrete amounts of energy depending on how its innards are gyrating. Bizarrely, an atom can also be in two different energy states—call them 0 and 1—at once, although that uncertain two-states-at-once condition "collapses" into one state or the other as soon as the atom is measured. "Entanglement" takes weirdness to its absurd extreme. Two atoms can be entangled so that both are in an uncertain two-ways-at-once state, but their states are perfectly correlated. For example, if Alice and Bob share a pair of entangled atoms and she measures hers and finds it in the 1 state, then she'll know that Bob is sure to find his in the 1 state, too, even before he measures it.
Obviously, Alice and Bob can generate a shared random key by simply entangling and measuring their atoms again and again. Crucially, if entanglement can be extended to a third atom held by Charlotte, then Alice and Charlotte can share a key. In that case, if Eve then tries to detect the key by surreptitiously measuring Bob's atom, she'll mess up the correlations between Alice's and Charlotte's atoms in a way that will reveal her presence, making the truly quantum network unhackable, at least in principle.
But first, physicists must entangle widely separated atoms. Now, Stephan Ritter of the Max Planck Institute of Quantum Optics in Garching, Germany, and colleagues have done just that, entangling two atoms in separate labs on opposite sides of the street, as they report online today in Nature.
As simple as this may sound, the researchers still needed a complete lab room full of lasers, optical elements, and other equipment for each node. Each atom sat between two highly reflective mirrors 0.5 mm apart, which form an "optical cavity." By applying an external laser to atom A, Ritter's team caused a photon emitted by that atom to escape from its cavity and travel through a 60-meter-long optical fiber to the cavity across the street. When the photon was absorbed by atom B, the original quantum information from the first atom was transferred to the second. By starting with just the right state of the first atom, the researchers could entangle the two atoms. According to the researchers, the entanglement could in principle be extended to a third atom, which makes the system scalable to more than two nodes.
"Every experimental step had to be just right to make this work," says Ritter, who works in the group of Gerhard Rempe. "Take, for example, the optical cavity. All physicists agree that atoms and photons are great stuff for building a quantum network, but in free space they hardly interact. We needed to develop the cavity for that."
"This is a very important advance," says Toshiba's Shields, because it would enable technologists to share quantum keys on networks where the intermediate nodes can't be trusted and could also lead to more complex multiparty communication protocols based on distributed entanglement. "However," Shields cautions, "there is still a great deal of work to be done before the technology is practical." Miniaturization of the components that constitute one node will no doubt be on the researchers' wish list.
From: Science Now
** **
Suppertime after another fully busy family day. Tomorrow morning a blood test early then a trip to Westerville following Carol, Kim and the boys to Mary Lou’s for lunch then home with Carol while Kim and the boys return on to Cleveland.
Earlier you were thinking about the article Doug sent and your mind has decided that this is circumstantial evidence suggesting (to you) that as such communication can exist (in experimental form) presently then the comments before from the March 2011 Discover are even more probable.
** **
. . . The physicists used acoustic waves that had the effect of altering time for the photons . . .
. . . Suarez was sure that by messing up the time-ordering in this way, it would be impossible for the photons to coordinate their paths. He was proved wrong. On every run, the photons still met the same fate. Whatever causes the twin photons to behave in the same way, it must work independently of time. “There is no story that can be told within the framework of space-time that can explain how these quantum correlations keep occurring,” Suarez says. . . . (51)
. . . Suarez says, “Physics experiments cannot demonstrate the existence of God, but this test shows that today’s physics is compatible with all major religious traditions. There is strong experimental evidence for accepting that nonmaterial beings act in the world.” (52)
. . . Jean Staune, a mathematical physicist and philosopher at the Interdisciplinary University in Paris . . . puts it like this: The before-before experiment shows that “if an intelligence is directing quantum events, then that intelligence exists outside the material universe. But it doesn’t prove that such a mind exists.” (52)
From: “Physics of the Divine", Discover, Zeeya Merali, March, 2011, pp. 49-52.
** **
I realize I am putting my imagination and (wishful thinking) to work here but I cannot help but have a ‘distant hope’ that you, Amorella, are a form or a direction of an ‘outside intelligence’. To deny this hope would be false even though I appear quite nakedly foolish in stating the hope.
At least your comment is not based on arrogance. This whole concept is as a dream of yours orndorff and you don’t really care if you or your name is associated with this ‘dream’. You don’t really care if you exist, that is my point. Now, where is this coming from? That is your real question: is it from heart or soul or mind or a combination? That is your real interest here. – Amorella
Earlier today you saw a FB note on a page of one of your former Escola Graduada de Sao Paulo students. She was writing about balance within the heart or in the principles of Yin and Yang. And you suggested that a balance might be better found in heart and soul and mind. I mention this because whether you like it or not, this shows by example that you do believe there should be such a balance – that this ‘balance’ is based on a perceived human reality. – Amorella
Alas, Amorella, indeed this was a quick inner anxiety at the time I wrote the comment. I don’t like to admit such thoughts to myself because I am fearful, I suppose, that they will do me in. It is irrational and I feel I cannot afford to be irrational. The transparency is seeing these words on the screen add a clarification to me beyond the fiction of the Merlyn works. I cannot afford to confuse a storyline fiction with any aspect of human reality; that is also my point here.
Point taken and understood. However, in this case it is your heart that is quivering not your mind or soul. You soul appears (to you) indifferent to the concept of my being an outside-the-physical-universe entity. Your mind and imagination are at work because you think it would be “cool” if anyone could demonstrate a connection to a ‘real being-from-outside-the-physical’. To you it is like: “cool, that would be a cool book to read”. This goes back to why you have a Platonic-like mental sense of a ‘Form’ existing. You think that your imagination is the reason I exist as I do, so much so, that I can write your books and direct this blog. Accepting plausibility of such a ‘Form’ of any kind makes the concept even more likely to your mind. Your heart doesn’t really want to deal with it because of the ramifications (whether the Form exists in you or in someone else or just exists unknown) – in any case there are ramifications for the heart. - Amorella
I see – enormous ramifications, just as there are in the article on the “Long Distance Quantum Link”. I had not thought or realized that, but I do now see a connection. I see a spun thread of reason and imagination as to where this is coming from in my head. I have a question. “Why is my soul supposedly indifferent to this line of imaginative thinking?”
Offended or not, I can live or die with it either way, Amorella.
Of course you can, orndorff, otherwise you wouldn't keep keyboarding. (It would not be reasonable to you for a definition to define itself in any case.) - Amorella
Later, after some thought. This goes back to my original premise: "I am mostly fiction is a true statement." Alas, what a dark humor this present circumstance of definition unfolds. I think it is a secret 'joy' to my soul, but it is not so to my heartanmind.
Sometimes you hit the correct notes even though you are not listening. Indeed, visually quite funny. Enough for tonight. - Amorella
No comments:
Post a Comment