Posts Tagged ‘electrons’
Proton Transistor Could Help Machines and Organisms Communicate
Proton transport is important for several biological processes, notably mitochondrial respiration, and living organisms’ electrical signals are modulated using protonic and ionic currents. So a machine that could mimic this type of information transfer could be used, for example, to monitor biological processes. Someday it could even be used to integrate new devices, like prosthetics, or to control biological systems — say, opening ion channels within cells to allow drugs to pass through.
We’ve seen other systems designed to do this, like synaptic transistors, , and nanoscale devices that use proton-conductive proteins. But those are difficult to build, say Chao Zhong and colleagues at the University of Washington, writing in the journal . It would be useful to have a device based on the type of transistors we all know so well, simply using a different type of current.
In a first step toward functional protonics, Zhong and colleagues built a protonic field-effect transistor. It works exactly like an FET in an electronic system — it has a terminal, a gate and a drain, and it can send pulses of current. The device is partly made from a compound called chitosan, extracted from squid. It can be recycled from crab shells and squid pen discarded by the food industry, according to a . It is biodegradable, biocompatible and non-toxic, the researchers say. The chitosan absorbs water and forms hydrogen bonds, and protons that are dissociated from maleic acids move along this hydrogen-doped channel.
The main drawback for now is that this FET also uses silicon, so it couldn’t be used in the human body; its main use would likely be direct sensing of cells in a lab. But a biocompatible version using some other type of semiconductor could conceivably be implanted in a living organism, monitoring proton activity and sending it to a protonic — not an electronic — device.
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Lasers that Flash in a Quintillionth of a Second Could ‘Film’ Electrons as they Interact
Capturing electrons on “film” isn’t easy--imagine the shutter speed you would need to capture something moving so fast that it can rotate a central hub in 151 billionths of a billionth of a second. That’s how fast the electron orbiting a hydrogen nucleus is moving, so in order to capture it in the act you need something with attosecond resolution. In other words, you need a laser capable of pulsing at the attosecond scale.
Attosecond laser pulses have been demonstrated before, but they were too weak to actually measure electron dynamics. For that, you need something both fast and intense. This new laser system satisfies both requirements, and does so with a relatively simple setup.
To get super-short bursts of laser light, you need to combine light waves of different frequencies in a very precise way such that they reinforce each other. This is easier said then done, particularly because it’s hard to get two different laser beams synchronized precisely. To overcome this, the researchers constructed a setup that runs a single laser beam through a beam splitter, producing two beams of different frequencies that are nonetheless the same beam. And because they share the same origin, they remain in sync.
But they’re still not at the attosecond level yet. Several other things have to happen to reach the proper intensities and durations necessary for attosecond-scale measurements. But a paper the team recently published in Nature Photonics outlines the road to attosecond resolutions in such a way that other researchers think its only a matter of time (and, more specifically, a matter of amplification) before we’re looking at individual electrons in a way in which we’ve never seen them before.
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Magnetic Microprocessors Could Enable the Most Efficient Computers Physically Possible
For now, computers run on electricity, which means electrons moving around and generating waste heat. But a magnetic microprocessor would not need any electrons. Instead, it would use the polarity of nanoscale bar magnets to represent the 0 and 1 of binary memory. If the nanomagnets are packed close together, their poles will interact, serving as transistors and thereby allowing simple logic operations.
Jeffrey Bokor, UC Berkeley professor of electrical engineering and computer sciences, and grad student Brian Lambson are trying to develop these magnetic computers. Their goal is a computer that operates at the Landauer limit, which at room temperature equates to a loss of 18 millielectron volts of energy per operation. This is the minimum energy that a single logic operation, like AND or OR, would dissipate. A physicist named Rolf Landauer computed this limit 50 years ago.
That number, 18 thousandths of an electron volt, is the merest whiff of energy — for comparison, it is about half the thermal energy of atoms at room temperature. The Large Hadron Collider collides particles at a maximum of 7 trillion electron volts, which is equal to the energy you'd get from eating 0.00013 micrograms of a candy bar.
A computer that uses such infinitesimal power would be a major advancement, Bokor said in a Berkeley news release. If it the computer could work at colder temperatures, it would be even more efficient (the Landauer limit is proportional to temperature).
“Even if we could get within one order of magnitude, a factor of 10, of the Landauer limit, it would represent a huge reduction in energy consumption for electronics,” he said. “It would be absolutely revolutionary.”
Lambson and Bokor wanted to test the energy efficiency of a simple magnetic logic circuit and magnetic memory, so they conducted calculations and computer simulations. They found a simple memory operation, such as erasing a magnetic bit, “can be conducted with an energy dissipation very close, if not identical to, the Landauer limit,” the says.
Current tests of these systems still require an electrical current to generate a magnetic field, which flips or erases a nanomagnet’s polarity. But Bokor and colleagues hope that new materials, such as , could make the electrical currents unnecessary. A new era of magnetonics, instead of electronics, could be in our future.
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Pocket Particle Accelerators Like This One Could Bring Safer Nuclear Power to Neighborhoods
Meet EMMA, the Electron Model of Many Applications
A in the English countryside could be a harbinger of a safer, cleaner future of energy. Specifically, nuclear energy, but not the type that has wrought havoc in Japan and controversy throughout Europe and the U.S. It would be based on thorium, a radioactive element that is much more abundant, and much more safe, than traditional sources of nuclear power.
Some advocates believe small nuclear reactors powered by could wean the world off coal and natural gas, and do it more safely than traditional nuclear. Thorium is not only abundant, but more efficient than uranium or coal — one ton of the silver metal can produce as much energy as 200 tons of uranium, or 3.5 million tons of coal, as the calculates it.
The newspaper took a tour of a small particle accelerator that could be used to power future thorium reactors. Nicknamed EMMA — the Electron Model of Many Applications — the accelerator would be used to jump-start fissile nuclear reactions inside a small-scale thorium power plant.
Thorium reactors would not melt down, in part because they require an external input to produce fission. Thorium atoms would release energy when bombarded by high-energy neutrons, such as the type supplied in a particle accelerator.
Providing that stimulus is one obstacle to building small thorium reactors — but a new generation of accelerators like EMMA, and someday potentially even smaller, luggage-sized ones — could do the job.
EMMA is the first non- scaling, fixed-field, alternating-gradient (NS-FFAG) accelerator, qualities that make it easier to operate and maintain, more reliable and compact, more flexible and more efficient, according to . Other particle accelerators use alternating electric fields, which require special safety measures to guard against microwave exposure, for instance. EMMA’s alternating magnetic field gradients are a more efficient and cheaper way to accelerate particles to higher energies. (Brookhaven National Laboratory explains in more detail .)
EMMA operates at operates around 20 MeV, or 20 million electronvolts, a paltry amount for an atom accelerator. The Tevatron, for instance, accelerates particles to 1 tera-electron volts. The Large Hadron Collider is designed to speed them to 7 TeV. But thorium reactors would not need such high energies to initiate fusion.
British scientists are already working on a successor called PAMELA, the Particle Accelerator for Medical Applications, which will be used to treat cancer.
Click through to the for a full tour of EMMA, its sister apparatus ALICE (Accelerators and Lasers In Combined Experiments), and a description of British efforts to produce thorium power.
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Pocket Particle Accelerators Like This One Could Bring Safer Nuclear Power to Neighborhoods
Meet EMMA, the Electron Model of Many Applications
A in the English countryside could be a harbinger of a safer, cleaner future of energy. Specifically, nuclear energy, but not the type that has wrought havoc in Japan and controversy throughout Europe and the U.S. It would be based on thorium, a radioactive element that is much more abundant, and much more safe, than traditional sources of nuclear power.
Some advocates believe small nuclear reactors powered by could wean the world off coal and natural gas, and do it more safely than traditional nuclear. Thorium is not only abundant, but more efficient than uranium or coal — one ton of the silver metal can produce as much energy as 200 tons of uranium, or 3.5 million tons of coal, as the calculates it.
The newspaper took a tour of a small particle accelerator that could be used to power future thorium reactors. Nicknamed EMMA — the Electron Model of Many Applications — the accelerator would be used to jump-start fissile nuclear reactions inside a small-scale thorium power plant.
Thorium reactors would not melt down, in part because they require an external input to produce fission. Thorium atoms would release energy when bombarded by high-energy neutrons, such as the type supplied in a particle accelerator.
Providing that stimulus is one obstacle to building small thorium reactors — but a new generation of accelerators like EMMA, and someday potentially even smaller, luggage-sized ones — could do the job.
EMMA is the first non- scaling, fixed-field, alternating-gradient (NS-FFAG) accelerator, qualities that make it easier to operate and maintain, more reliable and compact, more flexible and more efficient, according to . Other particle accelerators use alternating electric fields, which require special safety measures to guard against microwave exposure, for instance. EMMA’s alternating magnetic field gradients are a more efficient and cheaper way to accelerate particles to higher energies. (Brookhaven National Laboratory explains in more detail .)
EMMA operates at operates around 20 MeV, or 20 million electronvolts, a paltry amount for an atom accelerator. The Tevatron, for instance, accelerates particles to 1 tera-electron volts. The Large Hadron Collider is designed to speed them to 7 TeV. But thorium reactors would not need such high energies to initiate fusion.
British scientists are already working on a successor called PAMELA, the Particle Accelerator for Medical Applications, which will be used to treat cancer.
Click through to the for a full tour of EMMA, its sister apparatus ALICE (Accelerators and Lasers In Combined Experiments), and a description of British efforts to produce thorium power.
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Electrons Are Incredibly Close to Being Perfect Spheres
The wee electron has gotten its most thorough physical examination yet, and scientists report that it is almost, almost . Researchers at Imperial College London have determined the electron is just 0.000000000000000000000000001 centimeter off from being perfectly round. Put another way, if the electron was magnified to the size of the solar system, it would deviate from immaculate rotundity by a magnitude equivalent to a human hair.
There are 26 zeroes after that decimal, in case you don’t feel like squinting to count them out. The good news is that this shows our best theories of quantum electrodynamics are not totally off. The bad news is that scientists still don’t know why everything exists.
This impressive precision is the result of experiments spanning more than a decade, using molecules of ytterbium fluoride. The research is published today in the journal Nature.Scientists at Imperial’s Centre for Cold Matter used a special laser and watched the motion of the molecules’ electrons. If the electrons were not perfectly round, their wobbling would distort the overall shape of the molecule.
“If the electron is not round, then when placed in the electric field, it will execute a gyrating motion, just like a spinning top,” researcher Jony Hudson, a physicist at Imperial College London, said in an email. “We saw no evidence of this gyrating motion.”
Scientists want to know whether the electron is round because of what it tells us about accepted theories of quantum electrodynamics, Hudson explained.
If the electron was oval-shaped instead of round, this would have suggested key differences between normal, everyday electrons and their antimatter alter egos, positrons. This could help explain why the universe has a preponderance of matter over antimatter, and therefore .
As far as modern physics can tell us, the universe consisted of equal parts matter and antimatter right after the Big Bang, and the two opposites immediately started annihilating each other. Everything should have been canceled out, but stars, planets and people exist, so something happened to break the symmetry between antimatter and matter, allowing matter to permeate the cosmos.
“In order to explain the matter-antimatter imbalance, there probably needs to be some difference between the particles and anti-particles that we haven't observed yet. A non-round electron would be clear evidence for such a difference,” Hudson said.
But it is round, so it looks like this physical difference is not the culprit. Experiments at the soon-to-be-shuttered Tevatron and the Large Hadron Collider will seek to figure this out in greater detail.
Still, it helps to get a handle on the size and appearance, as it were, of the smallest building blocks of our existence. For instance, last year, scientists led by Randolf Pohl of the Max Planck Institute for Quantum Optics in Garching, Germany, determined that the proton was than everyone thought. Better definitions of elementary particles help refine and bolster the best theories of quantum electrodynamics.
So why is the electron ever so slightly warped? It has to do with the interaction between electrons and clouds of other ephemeral matter.
“One of the things that quantum field theory has taught us is that what we call empty space is not really empty. Rather, the picture is that it is full of what physicists call ‘virtual particles.’ These are particles of matter and antimatter that spring in and out of existence fleetingly,” Hudson explains. “Any ‘real’ matter, like the electron, drags around a cloud of these virtual particles with it.”
Hudson and his colleagues actually measured the shape of the electron plus that little cloud. Interactions between the electron and the virtual particles result in that infinitesimally small distortion.
If the tiniest of tiny things is not perfectly round, can anything truly be a perfect sphere? Hudson said we can never know — we can just keep refining measurements to say, it is no more distorted than such-and-such. Perfect roundness is actually important for scientific experiments, such as the Gravity Probe B. The probe uses four gyroscopes made of quartz-silicon spheres that are in the Guinness Book of World Records for their flawlessness — but they are still just imperfect enough that scientists had to do a couple years of calculations to make sure their recently announced were correct.
Aside from its importance to our understanding of the fundamental properties of reality, the electron-measuring experiment could help build , Hudson said.
“Our work draws heavily from that field, and vice versa many of our developments are useful to the clock makers,” he said. It could also help simulate systems that are too complicated to study with current computers.
Not content with accuracy up to one octillionth of a centimeter, Hudson, co-author Edward Hinds and others at the Centre for Cold Matter are developing new methods that will improve their measurements even more. They are working on new ways to cool molecules to extremely cold temperatures and control their exact motion, which would be a major feat. Such technology could be used to control chemical reactions, for instance.
"These techniques that we have developed are quite general, and are finding application in many fields," Hudson said.
Researchers Build a Transistor Out Of a Single Electron
A stepping stone toward quantum computing and artificial atoms
SketchSET--or sketch-based single-electron transistor--contains a tiny 1.5-nanometer-wide island at its core that operates with just one or two electrons at a time. The ability to work at such small scales makes it ideal for several advanced computing applications, like quantum processors that would be orders of magnitude more powerful than existing supercomputers.
The tiny transistors could also enable ultradense memory that packs far more information into far less space than existing memory.
But the subatomic possibilities don’t end there. That tiny central island at the heart of the technology could also be used as an artificial atom, the researchers say. These in turn could be used to develop new classes of electronic materials, like superconductors with exotic properties not see in natural materials.
But the real upside here is in the intended application: computing. Because the transistors are oxide-based, they possess a ferroelectric property that allows them to act as solid-state memory. That means that even when they are powered down they can control the number of electrons on the island. The number of electrons dictate the ones and zeros that are the basis of computer memory, meaning that a future computer based on such transistors could hold its data even without external power.
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