Slashdot Mirror
New Nanodevice Creates a Near Perfect Electron Stream
SchrodingerZ writes "Scientists from the National Physics Laboratory of the United Kingdom have teamed up with the University of Cambridge to create a new electron pump that creates a single electron stream. "The device drives electrical current by manipulating individual electrons, one-by-one at very high speed." The pump takes single electrons, and pushes it over a barrier with an indent for the electron to fall into, and is then sent to the opposite side of the barrier with astounding precision. "By employing this technique, the team were able to pump almost a billion electrons per second, 300 times faster than the previous record for an accurate electron pump set at the National Institute of Standards and Technology (NIST) in the USA in 1996." Although the current was very small (150 picoamperes), this event could cause a shift from the ampere measure of current to a smaller, more precise unit of measurement for electrical current."
The last sentence was literally one of the stupidest things I've ever read here.
"The pump takes single electrons, and pushes it over a barrier with an indent for the electron to fall into, and is then sent to the opposite side of the barrier with astounding precision. "
What is pushed over the barrier? What is sent to the opposite side of the barrier?
Sentences like this need rewriting, at the very least until they actually make some semantic sense.
Can any science/physics gurus tell me what sort of practical applications this has?
We focus protons the same and we can start catching some ghosts.
Who you gonna call? SCIENCE!
Is that a valve that selectively lets through moray eels, but blocks all other Anguilliformes?
A billion electrons per-second = 1x10^9 which is a lot less than 1A.
A billion electrons per-second = 10^9/6.241x10^18 = 0.160nA = 160pA = 160x10^(-12) A (160 pico-amperes so pretty much the number in the article).
So while this might be a whole wack load electrons for this type of device it really is not much.
Also it might make you respect your hose wiring a little more.
Your 200A house service is (200*1A) = 1.2482x10^21 electrons per second.
Keep dreaming.
The computation/observation needed for the demon to do his thing exceeds the energy made available by doing so.
The idea here is to define the ampere as N electrons per second. This may make that possible. The number is around 6.241 Ã-- 10^18 electrons per second. Direct counts of electrons allow a precise, repeatable way to define an amp.
The goal is to define the fundamental units from measurable properties of the universe, so that reproduceable standards can be constructed. That's been achieved for time and length, but not mass. You can buy an atomic clock that gets its time measurement from the definition of the second. (HP used to make those, but that business was sold off from Agilent in 2006.) There's a method with a Kr-86 light source and interferometers to count out a meter in wavelengths of light. But there's no corresponding standard for mass. Mass is tied to a physical 1Kg weight stored in France, and everything has to be traced back to that, with each successive derived standard kilogram a little less accurate.
A kilogram ought to be defined as N atoms of something, but atom counting isn't quite good enough yet. There's a plan to define mass through the Planck constant, which means tying the standard of mass to the standard of current.
Three fundamental units are sufficient to lock down all the other units, and this is a step towards doing that.
It made perfect sense to me, though it was still stupid. What I understood from that line was that they wanted to come up with a new unit to actually replace the ampere, at least for small-scale currents, perhaps sort of like the Angstrom is used instead of nanometers in some fields. Of course, this is entirely different from redefining the ampere, which from the way you write it I take to mean they want a new way to reproduce it, much like they changed the definition of the meter many years ago from "the length of this exotic metal alloy rod" to "the distance of x number of wavelengths of some radioactive emission". I haven't read TFA (it's slashdotted).
Anyway, coming up with a new unit seems stupid to me. The whole reason SI units use prefixes like mega, giga, milli, micro, nano, pico, femto, etc. is so that you don't need new units for different scales, you just use the appropriate prefix. If this thing is in the picoamps, what's the problem? Aren't picoamps good enough? If that's too big, we still have femtoamps which are 1000 times smaller. But if that's not what the article says, then it's really a moot point.
As for the editors, I wonder that all the time. Between the horrible article summaries and the frequent slashdupes, they don't really seem to do much besides click "ok", and really don't deserve the title "editor". Of course, if you look at modern mainstream "journalism" these days, it's not much different. Spelling and grammar errors and terrible writing are commonplace these days in professional publications.
The problem isn't so much the (in)durability and bulk of the reference kilograms. It's more that our measurements of the kilograms' mass aren't precise enough (eg. sampling error greater than an electron's mass).
And more importantly, the transience of the mass in the kilogram. It does have a decay half life, though long, and is subject to electrostatic and photoelectric fluctuations in its electron population, and even migration of whole atoms in/out of the sample. And then there are relativistic differences when the kilogram and the sampler are accelerating relative to each other, which even thermal jiggling can achieve in significance at these tiny mass differences.
Now that we've identified the Higgs boson, we'll learn more about the Higgs field, and learn to measure mass at extremely precise degrees. The "standard" kilograms' measured mass will be seen to fluctuate both over time and among the standard samples by several orders of magnitude (or rather "minitude" ;).
I hope these new quantum experiments at nanoscale (and even femtoscale) give us fundamental measures that count tiny things (including energy cycles) like "electrons per coulomb" from the bottom, rather than statistically survey large things like kilograms and scale down. Both for the more precise and reliable measurements, and to study the tiny deviations among previously believed "identical" particles like electrons. I expect different quantum states of the same particle type will have different masses due to different energy levels among the states. Perhaps we'll establish reliable equivalencies between information and mass, an "E=mc^2" for "joules per iota". And perhaps due to other factors yet undetermined, like perhaps energy in entanglement, or perhaps other "subquantum" effects yet unobserved until our measuring devices are more precise than the variations in their states.
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make install -not war
It would consist of no particles or waves. A dark matter smoke ring would do the trick.
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make install -not war
Anyway, coming up with a new unit seems stupid to me. The whole reason SI units use prefixes like mega, giga, milli, micro, nano, pico, femto, etc. is so that you don't need new units for different scales, you just use the appropriate prefix. If this thing is in the picoamps, what's the problem? Aren't picoamps good enough?
You're right, that would be stupid—and, despite what the summary tries to tell us, that's not actually what the article's suggesting.
The ampere is currently (no pun intended) defined as the amount of current that must flow in two parallel wires a specific distance apart, in order to get a certain amount of (magnetic) force between them. (The Coulomb is then defined as the amount of charge that flows past a point in one second when the current is one Ampere.) That definition is good enough for most purposes today, but there are limits to the precision that can be achieved in an experiment that measures current using mechanical forces. If it's now practical to create a stream of precisely counted electrons, then we can define the Coulomb and Ampere directly in terms of numbers of electrons, which then has the potential of being much more precise.
So the value of the Ampere and Coulomb won't change (or at least, not significantly), because any new definition will be chosen to be consistent with the old one—but the way we pin down their meaning may do.
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They should name the unit something related to electricity which takes parts of the picoamperes name so it sounds sort of like it. I've got it! Pikachus!