National Security Agency and U.S. Army Fund Yale Research Into Amplifier That Pushes the Boundary of Quantum Physics
May 6th, 2010Yes, the obvious application is with quantum computers.
This will also, no doubt, be going into military satellites, and probably countless other surveillance systems at some point. The requirement for cryogenic temperatures might delay many applications, but, this is Uncle $ugar that we’re dealing with here.
I like the analogy used in the article:
The typical signal power that must be measured is on the order of one billionth of one billionth of a watt, equivalent to the power of a cell phone call signal received on the moon from someone on earth.
*grin*
So, what would it be able to do if it was on-board a satellite in a low earth orbit, for example?
The gadget requires cryogenic temperatures, which means temperatures below 150 °C, ?238 °F or 123 K. Here’s an interesting trivia question for any of the many physicists/space nerds/spooks who read Cryptogon:
What temperatures are achievable on-board satellites in various Earth orbits? Assume that the satellite is always in the shade, even on passes when the sun is hitting it. Maybe a large mirror, curtain or solar panel, etc is configured to shade the bird when its exposed to the sun. How cold might that thing get? (Bonus points for rendering the bird invisible to the blessed freaks who track classified satellites because they can’t help themselves.)
Via: Yale University:
If powerful new quantum computers are to reach their enormous potential, they will need amplifiers capable of transmitting signals so weak they consist of a single photon. In the May 6 edition of the journal Nature, a team of Yale scientists report creating an amplifier almost as efficient as the laws of quantum physics allow.
Quantum computers, like cell phones, depend upon sophisticated microwave amplifiers to ensure that information is accurately retrieved. However, all amplifiers contain inherent flaws – most notably flaws which produce random noise that can obscure the signal. In quantum mechanics, the Heisenberg uncertainty principle dictates that a small amount of noise is inevitable, no matter how good the amplifier.
“If you want take information out of the computer, you will have to amplify very weak signals,” said Michel Devoret, Frederick William Beinecke Professor of Physics and Applied Physics at Yale’s School of Engineering & Applied Science and senior author of the paper. “The aim of our research is to devise an amplifier for signals so tiny they have only one photon in them.”
“Michel and his team have developed a new design for a practical amplifier using superconducting electrical circuits at cryogenic temperatures that comes very close to the ideal limit of this minimum amount of added noise,” said Steven M. Girvin, deputy provost for science and technology, the Eugene Higgins Professor of Physics & Applied Physics at Yale’s School of Engineering & Applied Science and a co-author of the work.
The Yale effort to build a quantum computer based on superconducting electrical circuits relies on incredibly weak microwave signals to both control and measure the quantum state of the computer. The typical signal power that must be measured is on the order of one billionth of one billionth of a watt, equivalent to the power of a cell phone call signal received on the moon from someone on earth.
Other Yale authors on the paper are: Nicola Bergeal, Flavius Schackert, Michael Metcalfe, R. Vijay, Vladimir Manucharyan, Luigi Frunzio, Daniel Prober, and Robert Schoelkopf.
Researchers at the University of Maryland and the University California, Berkeley also contributed to the paper.
The work was funded by the National Science Foundation, the National Security Agency and the Army Research Office.
Let me try to answer the question. The spitzer space telescope is a satellite that need to be kept cool to work properly. They managed to keep it at 3K (-270 C) for about 6 years until it ran out of cooling fluid. Now that it is out of cooling, they still manage to keep it really cold (31K or -242° C) with different technic including the sun shielding you talked about. That is still well below the temperature required (123K or -150C) in this article.
Now that being said, this telescope is really far away from earth, so that helps at keeping it cool. A satellite in close earth orbit will be harder to chill. Unfortunatly i’m not so sure about exactly how much it could warm the satellite, but based on what we need about the spitzer telescope, I would say it is totally possible to keep it cool enough for some years with cooling fluids. I don’t know what would happen with no cooling fluid at all, but I wouldn’t bet it’s impossible at all.
Wow! 3K with cooling fluid and 31K with the heat shield.
Given the example in the article, about the moon and the cell phone, it doesn’t seem like a low orbit would be necessary.
You know, I almost wonder if the quantum computer aspect of this is somewhat of a distraction. Of course, someday, it will be useful for quantum computers, but, based on the information you have provided, it would seem that this could be put to use on surveillance satellites right now—at least in theory. Maybe there are other limiting factors to using these amplifiers that I can’t even begin to imagine.