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Scientists Find Flaw in Quantum Dot Construction
ThePolkapunk writes "Scientists have been having problems in predicting the behavior of Quantum Dots, which are considered to be the most likely material to be used to build nanocomputers. Physorg is reporting that physicists at Ohio University believe they've found the problem, and it's with a flaw in the construction of quantum dots. If their theory pans out, "It's one more step towards the holy grail of finding a better quantum bit, which hopefully will lead to a quantum computer."" We first mentioned this about six years ago.
to ask this...
The guy who wrote "the wellstone" is convinced that quantum dots can also be used to create programmable matter, something he came up with in one of his science fiction books.
I am just curious. Is this (programmable matter via quantum wells/dots) something that actual work is being done on anywhere, or that actual signs of progress can be seen in, or that Mr. McCarthy has the actual capacity to encourage actual science work to be done on? Or is this just a lone science fiction author running around trying to convince people to take him seriously?
Irritable, left-wing and possibly humorous bumper stickers and t-shirts
I built my caravan from nanoscale quantum dots.
It got rusty really quickly, and the seals on the doors leak.
I would recommend other people avoid using them for building things.
"Scientists have been having problems in predicting the behavior of Quantum Dots"
Couldn't they use the random number generator that sees into the future to predict the behavior of quantum dots? It was posted in Slashdot's Science section without the Funny Foot icon so it must be valid, just like the tsunami creatures. (Seriously, how can we not be sceptical about anything posted on Slashdot these days? When I read this headline the first thing I did was checking out on Google and Randi.org if quantum dots aren't just another new quack pseudoscience, and before I managed to verify their validity I had no time to read the article in question. Isn't there something wrong with a news source when the first thing I do is a research before I can trust anything I read? Isn't that a job of editors to verify their sources before posting stories? I just don't get it.)
Sincerely,
Pan Tarhei Hosé, PhD.
"Homo sum et cogito ergo odi profanum vulgus et libido."
Quantum computers have the capability to break most encryption schemes. This would definitely be a revolution.
Philosophy.
Bad, bad geek! There's no such thing as "too much computer power"
It's Ohio University... Athens, Ohio not to be confused with Ohio State University an hour and a half northwest in Columbus.
Web hosting that doesn't suck!Dreamhost
"New & used Quantum Dots. aff Check out the huge selection now" ...ebay ad running next to TFA
We have The Ohio State University and Ohio University, but no University of Ohio... at least not in Ohio. [NOTE: There are a number of other state-funded Universities: Bowling Green, Toledo, Akron, Kent, Miami, Case Western Reserve, et. al., but none of them have 'Ohio' in their name, except maybe Miami, which is often called "Miami of Ohio" to distinguish it from Miami University in Florida.]
"Lawyers are for sucks."
- Doug McKenzie
This only applies to self-assembled quantum dots. The ones created by lithography or otherwise manually constructed didn't have this problem in the first place. Don't get too excited (unless you're working with photoexcitation in self-assembled QDs, in which case this might matter to you).
Bugrit! Millenium hand and shrimp!
They could be finding cures to cancer, or making better space shuttles, or doing a ton of things with applications that would be useful
Uh.. wow.
The people designing better computers aren't curing cancer because they aren't biologists. It isn't like intelligence is just something you can put in a pipe and direct it whereever you want. Some people are just better at certain things than others. Meanwhile the kinds of people who gravitate toward research fields tend to only be effective when they're doing things they find interesting and exciting. What they personally most enjoy or can best apply their talents toward may or may not be the most important thing in the world, but if it's productive and makes some sort of difference, who are we to question?
And why target the people improving computing power, and not any other "nonuseful" field? In particular, why on earth target people like the ones from this article, who are improving computing power by expanding our understanding of and ability to harness basic physics, and working in an area where discoveries potentially have direct applicability to all kinds of other nanoscale technologies, like, I don't know, smart medicines.
Even if your "couldn't they be doing something more useful" thing made sense, your examples are very poor. Better space shuttles aren't being built for a lack of ingenuity, they're being built for a lack of funding. And curing cancer in particular is a horrible example because much of the interesting expanding work in the medical research field at the moment is in bioinformatics. Meaning that cancer research would directly and seriously benefit from a major jump in the capacity of computing power, such as the one these nanocomputer people could make possible.
Irritable, left-wing and possibly humorous bumper stickers and t-shirts
How do you verify the accuracy of Slashdot stories? We don't. You do. :) If something seems outrageous, we might look for some corroboration, but as a rule, we regard this as the responsibility of the submitter and the audience. This is why it's important to read comments. You might find something that refutes, or supports, the story in the main.
Answered by: CmdrTaco
Last Modified: 10/28/00
wud
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.
40% of the US economy is dependent on applications of quantum mechanics, and all of the rest of it indirectly feels the effects.
WARNING: there is a trojan on your
Here is the official press release on the Ohio University website.
Is there some relationship between /. and PhysOrg? If so, Commander Taco should be ashamed of it... PhysOrg is an eyeball tarpit, it NEVER credits the original article or provides a link back to it. Never. Not once. It might as well be dead trees...
Here's the original article at Ohio University without the PhysOrg spam.
Heisenberg was driving down the road, and a policeman pulled him over. He asked, "do you know how fast you were going?" Heisenberg replied, "no, but I can tell you where I am."
Hyperbole is the worst thing ever.
Sounds like they OU an apology... ;)
"Was it a millionaire who said 'Imagine No Posessions?'" -- Elvis Costello
That pretty much is what researchers in quantum computing are trying to do, it's a whole different ballgame. For example, In classical computing, 3 bits lets you put a system into exactly one of 8 (2^3) distinct states. However a quantum computer with 3 qubits will let you put the system into a superposition of these eight states, such that the superpositiong (ie, wavefunction) is properly normalized.
Quantum mechanics works in a whole different mathematical basis (Hilbert Space or Fock Space). The algebras of these spaces is quite different from classical computing, so yes, it's going to be a whole new way of looking at computing, at least at the lowest level.
On a side note, it sounds like you have just read some Thomas Kuhn, as per your frequent usage of 'paradigm', along with comparing 'evolution' to 'revolution'.
make world, not war
That's the problem. In this era of budget reduction, our scientists are now forced to buy their Quantum Dots off of Ebay.
Unfortunately, not only have many of these dots been defective, following the installation and usage instructions included with the Dot have left many of our top scientists sterile.
It is possible that this is a plot by Al Queida to weaken the population of intellectuals in the US.
Would that be in Universe A or Universe 1?
We first mentioned this six years ago...
How absurd and inanely pretentious. It's astounding that the search engine the editors are using allows them to say "it's a dupe from six years ago" but not be able to recognize the dupe from yesterday. Sheesh.
sarchasm: The gulf between the author of sarcastic wit and the person who doesn't get it.
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Now somebody's obviously banking on the idea that quantum physicists are most likely to fall for the six step scheme. Perhaps they'll get stuck on "Step 5: ???" and spend the rest of their natural lives trying to solve for ???.
https://www.eff.org/https-everywhere
Doesn't the article read just like your typical Star Trek plot?
You have a noble experiment:
Nanoscientists dream of developing a quantum computer, a device the size of a grain of sand that could be faster and more powerful than today's PCs.
So, after they have
blasted the quantum dots with light to create the quantum mechanical state
they encounter the problem:
they couldn't consistently control that state
So, the science officers get the work and after some time the find out the cause of the problem:
the wetting layer caused interference, instead of allowing the light to enter the dot and trigger the quantum state
And, after some hard thinking Wesley Crusher...
suggests that scientists could tweak the process by re-focusing the beam of light or changing the duration of the light pulses to negate the effects of the wetting layer!
And the day is saved.
First, I know the terms Q-dots is a trademark, and I think "Quantum Dots" might be trademarked by the same company. So don't give them so much mindshare, since that company isn't really even on the "forefront" of the technology. Call them fluorescent semiconductor nanocrystals, because it actually describes what they are, so people won't think they're being used in quantum computing (not yet, at least).
Second, these nanocrystals blink. Every researcher I've seen speak about these things mentions the blinking, but only recently did I hear someone give an explanation: poor surface coating allows electrons to leak out of the the crystal.
Third, Semiconductor nanocrystals are made of several layers. The central layer is usually Cadmium Selenide (CdSe), coated by Zinc Selenide. The second coating has a higher band gap energy, so electrons get "stuck" inside the nanocrystal and then emit photons when they drop back to the ground state. Unfortunately, these nanocrystals are very sticky without more coatings. Often a PEG (polyethylene glycol) linker is stuck on the outside of the ZnSe surface to inhibit these non-specific binding events.
Last, semiconductor nanocrystals are cool because you can excite them at many wavelengths, but the emitted photon's wavelength (color) depends on the size of the crystal being illuminated. The bigger the crystal, the redder the emission. That makes them size tunable, and easily multiplexible. Eventually, that could be really useful for quantum computing (or digital video, possibly).
Si la vida me da palo, yo la voy a soportar Si la vida me da palo, yo la voy a espabilar
And with RSA & friends no longer usable, how do you propose to distribute your AES etc. keys? It doesn't matter how strong your symetric cipher is, if you can't securly distribute the keys, you're fucked.
The wetting layer is a by-product of the method used to grow the dots.
I can talk about InAs dots in GaAs, which are the ones I know best. In order to grow the self-assembled dots, you first grow enough layers of GaAs so that you end up with an atomically flat layer of GaAs. Then, you start growing layers (one atomic layer at a time, such is the magic of molecular beam epitaxy!), until a certain "critical height" (I think it's around 5 monolayers). At that time, you stop the growth for a little while and the InAs layer spontaneously forms "droplets" in the GaAs surface, which will be the quantum dots after you grow some GaAs on top. The problem is that the droplets don't use up all the InAs that was deposited, so some remains in the surface and forms the so-called "wetting layer" which behaves similarly to a quantum well. I don't remember any references off the top of my head, but look for articles on the "Stranski-Krastanov growth mode".
site:slashdot.org "quantum dot"
Backups are for wimps. Real men post their data in comments and have slashdot mirror it
I think it's important to point out that what these people are doinmg is not the whole story about quantum dots. They use a particular technique, and they found a way to improve it, but other people are using completely different techniques that have different advantages and disadvantages. Using "Scientists Find Flaw in Quantum Dot Construction" as a title is very misleading; it's like if an amelioration to firefox was reported as "Scientists find flaw in networking that could fix the internet".
>Shor's algorithm is in P, not NP
Yikes. First of all, P is contained in NP. In other words, it's impossible for something to be in P but not in NP.
Secondly, Shor's algorithm is NOT in P. P is the set of languages decided in polynomial time by a deterministic Turing machine. Shor's algorithm runs in polynomial time, but it is NOT in P.
This is an important point for math geeks. The reason quantum computers solve these problems more quickly is that they are not deterministic. They can therefore solve Non-deterministic Polynomial problems in polynomial time. Assuming, of course, that it's actually possible to build a quantum computer.
Socialism: a lie told by totalitarians and believed by fools.
Wrong, viruses have been evolving for millions of years to use other life forms to survive and reproduce.
There is a law of biology that says something like: any parasite evolves to be less harmfull to its host(s).