Except that liquid helium is a consumable part of an MRI. You can capture the boil-off (or at least try), but you are going to constantly lose some of that boil-off to diffusion through bag/pipes/pump oil/etc. So if the cost of helium goes up, the cost of replacing gas in these systems goes up as well. And that is the scary thought.
So let me get this straight. You want everybody in the world to carry around synchronized OTPs for every computer they could possibly interact with securely, and all servers to store enough OTPs for all their users, and then, as the OTP protocol requires, throw out the pieces of the pad you've already used? The whole point of a OTP is to deny any sort of pattern formation in the encrypted data due to patterns present in the key and the encrypted stream by making sure there is absolutely no correlation between the two.
Then there is the distribution question. How do you make sure both sides of the OTP are the exact same? Without using quantum encryption protocols (sorry, I don't remember the current distance restrictions on these), there is no known secure way to distribute OTPs short of meeting in person with the person you want to share a pad with, and then making two exact copies of the data.
I'll take Diffie-Hellman for now. If we reach a point where quantum encryption becomes ubiquitous (I'm not holding my breath), then we can talk about OTP as a serious option.
I'll do you one better. When I got my first aid training here in the Netherlands the instructor pretty much told us that if we ever visited the States we should only give aid in life-threatening situations, because the risk of being sued is too great to do so under other circumstances.
Sadly, this does not surprise me at all. But that's another rant for another time.
In theory, there would be no standing to sue under the good samaritan laws.
Not true. One of the things they pound into your head when you take a CPR / First Aid course through the Red Cross is that you are covered by the Good Samaritan laws only if you do not accept a reward or compensation for your help. I guarantee the doctor who built the dialysis machine was paid for the effort.
I think the proper phrase is "would not have gotten to the moon that quickly." Once it is known that something is possible, then scientists can move rather quickly to reproduce it and make it an engineering task. Working directly with Von Braun simply sped up the process, since we didn't need to reproduce his work first.
Granted, values in the 50's of Tesla seem pretty big, considering that the ambient magnetic field on Earth is about 0.5 Tesla. I'm just quibbling on units -- the Earth's magnetic field is 0.5 gauss, or, 50 microTesla. Other than that, I agree with your comment 100%.
The primary reason this is a crisis is because a large amount of basic physics research is done at liquid helium temperatures or lower, and the easiest (and up until recently) cheapest way to do that research has been to consume liquid helium to cool down experiments. If the cost of helium goes up, then it will become difficult to continue funding for the low temperature community. That includes things like superconductivity research.
There are new products on the market now that use closed cycle refrigerators to do the cooling (still takes helium, but contains it rather than consuming it), but many of the scientists doing low temperature physics don't have the money to spend on a new cryostat in order to take advantage of the new technology. In addition, the closed cycle refrigerators don't have the raw cooling power of the liquid helium.
They might have increased budgets, but not in the physical sciences. In the biological sciences, through NIH, yes. They have gone up. But physics budgets have been almost dry for years.
The touch screen voting machine I used this morning did have a printer attached to it, and the final step in the ballot was for me to verify that the paper tape scrolling past held an accurate record of my vote.
I'm not sure of the manufacture, but for anybody curious, I'm in San Diego, CA.
Quantum key distribution is cryptographically equivalent to one time pads, but better -- it solves the key distribution problem; you don't need to take all the one-time pads with you when you leave.
Go watch a fleet prepare for setting to sea, and you'll see them loading one time pads onto the ship by forklift.
The quantum computing method of breaking public key encryption isn't based on brute force, like the classical methods are. Shor's algorithm is in P, not NP.
Re:Redundant Systems and Fluid Dynamics
on
Fluid Logic Chips
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· Score: 1
What this will do, is enable better redundant designs for deep space probes.
You might have problems with your fluid freezing in deep space; the background temperature is kinda cold.
The point isn't to use the quantum entanglement to directly pass information back and forth; rather it is to distribute a key for a one time pad. And one time pads are provably secure, since every different one time pad gives you a different (and equally plausible) decryption of the message.
Hence, if you really want to gripe about the name, I suppose you could call it quantum key distribution.
Imagine what kind of encryption you could do with quantum computing. When the first computers were built, most of the standard methods of encryption became obsolete -- ones that usually involved simple letter-substitution. That wasn't the end of encryption; those same computers enabled new ways to encrypt messages.
Bennet and Brassard showed in 1984 that you could use quantum information methods to distribute a one time pad securely, with anybody trying to interrupt the stream corrupting the pad, making both the copy recieved by the legitimate user and the copy recieved by the interloper different than the one used by the sender.
These systems are being implemented as we speak. IBM has a system that will cover 20 miles through fiber, and LANL has a system that will cover almost 5 miles through open air.
Last I checked, the best algorithms for factoring were still in NP; otherwise public key encryption would never be trusted for anything.
For that matter, the same algorithm, with very little change, also solves the discrete log problem and the hidden subgroup problem in polynomial time.
As for quantum data being "transient," it is true that most of the quantum information systems have decoherence problems. But, if memory serves, there are some with coherence times that can be measured in seconds. With refocusing techniques, you could probably hold onto a qubit state all day in those systems.
It'll be a while before we're ready to do that, though.
And, as others have pointed out, this is hardly the first time anybody has shown a CNOT gate. Chuang did this at IBM a few years back at least as part of his implementation of Shor's Algorithm to factor 15. I also believe it has been shown in a few other systems, but I'd need to dig through some archives first and track references.
It's not that bad -- a good dilution refrigerator with an adiabatic demagnetization stage will do it effectively continuously, so long as you remember to put in LHe every now and then to keep the He-4 pot running.
Why do you need laser cooling to study superfluids? Helium 4 becomes superfluid at around 2 K. You can achieve that temperature by taking liquid He (4.2 K), pump on it, and let evaporative cooling work its magic. (Actually, pumping on it lets you get down to around 1.2 K, but what's a Kelvin or two between friends?)
BECs are formed using the laser traps, but the ammount of material cooled is measured in atoms, and it cannot sustain any kind of heat load. Superfluids (as far as I know, the only two known are He 4 and He 3) don't require these extreme techniques to study.
Depends on which part of the network you're talking about. Their resnet people are a joke (at least, they were five years ago). I remember their shutting down my network connection because they found my linux box (running no external services whatsoever, btw). When I called them about it, they had a problem with the idea that I might change my MAC address.
But, if you go to the campus backbone people, they know their shit. If memory serves, they can be found in Engineering I, or perhaps Phelps. It's been a while.:)
I was just going off of the books I have on the shelf. I've perused Shankar, but, like Sakurai, it just seems to skip too many basic ideas, and delves into the Hamiltonian formulation of quantum without discussing the consequences at length. Frankly, the best quantum book I've used was a professor's notes on the subject.
And I agree that Shultz is basic, but it is a good introduction book. I've never seen Wald, so I can't comment on it.
If you want a good understanding of most of the stuff posted here about physics, then you really need a good background in some specific specialty in physics, like astro or semiconductor physics.
If you're interested in semiconductors, for instance, you'll want a good set of books for basic physics, then E&M, quantum mechanics, statistical mechanics and thermodynamics, and finally a good book on many body problems (a.k.a. condensed matter physics). In many cases, the textbooks are behind the times (especially for quantum and condensed matter), and the only way to really catch up is to read the research articles themselves.
Astro requires a lot of the same subjects (and a hefty dose of GR and optics to boot). Cosmology gets even crazier.
But, for the classical stuff, a list is fairly easy to provide:
Freshman Physics: (pick any single set, but understand calculus first)
Feynman Lectures
Halliday and Resnick
Serway
Sears and Zemansky
E+M
Griffiths (good all around book)
Jackson (only for the hardcore)
Landau and Lifshitz
Classical Field Theory
Marion and Thornton
Goldstein
Landau and Lifshitz
Quantum Mechanics
To my knowledge there isn't a really good quantum book that doesn't require some foreknowledge of the subject, although I've been told that Dirac's book is readable.
Statistical Mechanics
Goodstein (quite readable, light on the math)
Condensed Matter
Kittel
Ashcroft and Mermin
GR
Schultz
And, just because it's so important, Math
Boaz
Arfken and Weber
Carrier, Krook and Pearson
Mind you, the books I just outlined probably cost in excess of a thousand dollars if you buy them all. The big problem is, physics is a big area to want to understand, and a working knowledge of the subject requires years of dedication to that goal.
What software are you using for data aquisition? National Insturments has a particularly nice package called Labview, and there is a Linux version available. Most of the labs here use it as their primary data acquisition software. (Admitedly, most of the groups use windows for their aquisition environment.)
National Insturments also provides drivers for most of their hardware for Linux as well.
Slashdot Mirror
Except that liquid helium is a consumable part of an MRI. You can capture the boil-off (or at least try), but you are going to constantly lose some of that boil-off to diffusion through bag/pipes/pump oil/etc. So if the cost of helium goes up, the cost of replacing gas in these systems goes up as well. And that is the scary thought.
So let me get this straight. You want everybody in the world to carry around synchronized OTPs for every computer they could possibly interact with securely, and all servers to store enough OTPs for all their users, and then, as the OTP protocol requires, throw out the pieces of the pad you've already used? The whole point of a OTP is to deny any sort of pattern formation in the encrypted data due to patterns present in the key and the encrypted stream by making sure there is absolutely no correlation between the two.
Then there is the distribution question. How do you make sure both sides of the OTP are the exact same? Without using quantum encryption protocols (sorry, I don't remember the current distance restrictions on these), there is no known secure way to distribute OTPs short of meeting in person with the person you want to share a pad with, and then making two exact copies of the data.
I'll take Diffie-Hellman for now. If we reach a point where quantum encryption becomes ubiquitous (I'm not holding my breath), then we can talk about OTP as a serious option.
It's always nice to see complex engineering projects that work. It gives the impression that theory and reality are getting closer.
Theory and reality are the same, at least in theory.
But theory and reality are not the same in reality. That's the difference.
I'll do you one better. When I got my first aid training here in the Netherlands the instructor pretty much told us that if we ever visited the States we should only give aid in life-threatening situations, because the risk of being sued is too great to do so under other circumstances.
Sadly, this does not surprise me at all. But that's another rant for another time.
In theory, there would be no standing to sue under the good samaritan laws.
Not true. One of the things they pound into your head when you take a CPR / First Aid course through the Red Cross is that you are covered by the Good Samaritan laws only if you do not accept a reward or compensation for your help. I guarantee the doctor who built the dialysis machine was paid for the effort.
I think the proper phrase is "would not have gotten to the moon that quickly." Once it is known that something is possible, then scientists can move rather quickly to reproduce it and make it an engineering task. Working directly with Von Braun simply sped up the process, since we didn't need to reproduce his work first.
--
Just another condensed matter physicist.
The primary reason this is a crisis is because a large amount of basic physics research is done at liquid helium temperatures or lower, and the easiest (and up until recently) cheapest way to do that research has been to consume liquid helium to cool down experiments. If the cost of helium goes up, then it will become difficult to continue funding for the low temperature community. That includes things like superconductivity research.
There are new products on the market now that use closed cycle refrigerators to do the cooling (still takes helium, but contains it rather than consuming it), but many of the scientists doing low temperature physics don't have the money to spend on a new cryostat in order to take advantage of the new technology. In addition, the closed cycle refrigerators don't have the raw cooling power of the liquid helium.
Let's hope the PETA people want to watch the roaches from very close by as the radiation is applied.
They might have increased budgets, but not in the physical sciences. In the biological sciences, through NIH, yes. They have gone up. But physics budgets have been almost dry for years.
The touch screen voting machine I used this morning did have a printer attached to it, and the final step in the ballot was for me to verify that the paper tape scrolling past held an accurate record of my vote.
I'm not sure of the manufacture, but for anybody curious, I'm in San Diego, CA.
"Actually, they both taste like malted battery acid. Let's go for a milk."
Lovely. Whole or skim?
Quantum key distribution is cryptographically equivalent to one time pads, but better -- it solves the key distribution problem; you don't need to take all the one-time pads with you when you leave.
Go watch a fleet prepare for setting to sea, and you'll see them loading one time pads onto the ship by forklift.
The quantum computing method of breaking public key encryption isn't based on brute force, like the classical methods are. Shor's algorithm is in P, not NP.
You might have problems with your fluid freezing in deep space; the background temperature is kinda cold.
Hence, if you really want to gripe about the name, I suppose you could call it quantum key distribution.
Bennet and Brassard showed in 1984 that you could use quantum information methods to distribute a one time pad securely, with anybody trying to interrupt the stream corrupting the pad, making both the copy recieved by the legitimate user and the copy recieved by the interloper different than the one used by the sender. These systems are being implemented as we speak. IBM has a system that will cover 20 miles through fiber, and LANL has a system that will cover almost 5 miles through open air.
Last I checked, the best algorithms for factoring were still in NP; otherwise public key encryption would never be trusted for anything.
For that matter, the same algorithm, with very little change, also solves the discrete log problem and the hidden subgroup problem in polynomial time.
As for quantum data being "transient," it is true that most of the quantum information systems have decoherence problems. But, if memory serves, there are some with coherence times that can be measured in seconds. With refocusing techniques, you could probably hold onto a qubit state all day in those systems.
It'll be a while before we're ready to do that, though.
And, as others have pointed out, this is hardly the first time anybody has shown a CNOT gate. Chuang did this at IBM a few years back at least as part of his implementation of Shor's Algorithm to factor 15. I also believe it has been shown in a few other systems, but I'd need to dig through some archives first and track references.
It's not that bad -- a good dilution refrigerator with an adiabatic demagnetization stage will do it effectively continuously, so long as you remember to put in LHe every now and then to keep the He-4 pot running.
Why do you need laser cooling to study superfluids? Helium 4 becomes superfluid at around 2 K. You can achieve that temperature by taking liquid He (4.2 K), pump on it, and let evaporative cooling work its magic. (Actually, pumping on it lets you get down to around 1.2 K, but what's a Kelvin or two between friends?)
BECs are formed using the laser traps, but the ammount of material cooled is measured in atoms, and it cannot sustain any kind of heat load. Superfluids (as far as I know, the only two known are He 4 and He 3) don't require these extreme techniques to study.
Depends on which part of the network you're talking about. Their resnet people are a joke (at least, they were five years ago). I remember their shutting down my network connection because they found my linux box (running no external services whatsoever, btw). When I called them about it, they had a problem with the idea that I might change my MAC address.
:)
But, if you go to the campus backbone people, they know their shit. If memory serves, they can be found in Engineering I, or perhaps Phelps. It's been a while.
I was just going off of the books I have on the shelf. I've perused Shankar, but, like Sakurai, it just seems to skip too many basic ideas, and delves into the Hamiltonian formulation of quantum without discussing the consequences at length. Frankly, the best quantum book I've used was a professor's notes on the subject.
And I agree that Shultz is basic, but it is a good introduction book. I've never seen Wald, so I can't comment on it.
If you want a good understanding of most of the stuff posted here about physics, then you really need a good background in some specific specialty in physics, like astro or semiconductor physics.
If you're interested in semiconductors, for instance, you'll want a good set of books for basic physics, then E&M, quantum mechanics, statistical mechanics and thermodynamics, and finally a good book on many body problems (a.k.a. condensed matter physics). In many cases, the textbooks are behind the times (especially for quantum and condensed matter), and the only way to really catch up is to read the research articles themselves.
Astro requires a lot of the same subjects (and a hefty dose of GR and optics to boot). Cosmology gets even crazier.
But, for the classical stuff, a list is fairly easy to provide:
Freshman Physics: (pick any single set, but understand calculus first)
Feynman Lectures
Halliday and Resnick
Serway
Sears and Zemansky
E+M
Griffiths (good all around book)
Jackson (only for the hardcore)
Landau and Lifshitz
Classical Field Theory
Marion and Thornton
Goldstein
Landau and Lifshitz
Quantum Mechanics
To my knowledge there isn't a really good quantum book that doesn't require some foreknowledge of the subject, although I've been told that Dirac's book is readable.
Statistical Mechanics
Goodstein (quite readable, light on the math)
Condensed Matter
Kittel
Ashcroft and Mermin
GR
Schultz
And, just because it's so important, Math
Boaz
Arfken and Weber
Carrier, Krook and Pearson
Mind you, the books I just outlined probably cost in excess of a thousand dollars if you buy them all. The big problem is, physics is a big area to want to understand, and a working knowledge of the subject requires years of dedication to that goal.
Well, reading the duckpins page, I see that the sequal is coming out in 2034.
National Insturments also provides drivers for most of their hardware for Linux as well.