More Powerful Supercomputers? New Device Could Bring Optical Information Processing

More Powerful Supercomputers? New Device Could Bring Optical Information Processing

  10:35:00 AM    Science Lover

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Researchers have created a new type of optical device small enough to fit millions on a computer chip that could lead to faster, more powerful information processing and supercomputers.

This illustration shows a new "all-silicon passive optical diode," a device small enough to fit millions on a computer chip that could lead to faster, more powerful information processing and supercomputers. The device has been developed by Purdue University researchers. (Credit: Birck Nanotechnology Center, Purdue University)

The "passive optical diode" is made from two tiny silicon rings measuring 10 microns in diameter, or about one-tenth the width of a human hair. Unlike other optical diodes, it does not require external assistance to transmit signals and can be readily integrated into computer chips.

The diode is capable of "nonreciprocal transmission," meaning it transmits signals in only one direction, making it capable of information processing, said Minghao Qi (pronounced Chee), an associate professor of electrical and computer engineering at Purdue University.

"This one-way transmission is the most fundamental part of a logic circuit, so our diodes open the door to optical information processing," said Qi, working with a team also led by Andrew Weiner, Purdue's Scifres Family Distinguished Professor of Electrical and Computer Engineering.

The diodes are described in a paper to be published online Dec. 22 in the journal Science. The paper was written by graduate students Li Fan, Jian Wang, Leo Varghese, Hao Shen and Ben Niu, research associate Yi Xuan, and Weiner and Qi.

Although fiberoptic cables are instrumental in transmitting large quantities of data across oceans and continents, information processing is slowed and the data are susceptible to cyberattack when optical signals must be translated into electronic signals for use in computers, and vice versa.

"This translation requires expensive equipment," Wang said. "What you'd rather be able to do is plug the fiber directly into computers with no translation needed, and then you get a lot of bandwidth and security."

Electronic diodes constitute critical junctions in transistors and help enable integrated circuits to switch on and off and to process information. The new optical diodes are compatible with industry manufacturing processes for complementary metal-oxide-semiconductors, or CMOS, used to produce computer chips, Fan said.

"These diodes are very compact, and they have other attributes that make them attractive as a potential component for future photonic information processing chips," she said.

The new optical diodes could make for faster and more secure information processing by eliminating the need for this translation. The devices, which are nearly ready for commercialization, also could lead to faster, more powerful supercomputers by using them to connect numerous processors together.

"The major factor limiting supercomputers today is the speed and bandwidth of communication between the individual superchips in the system," Varghese said. "Our optical diode may be a component in optical interconnect systems that could eliminate such a bottleneck."

Infrared light from a laser at telecommunication wavelength goes through an optical fiber and is guided by a microstructure called a waveguide. It then passes sequentially through two silicon rings and undergoes "nonlinear interaction" while inside the tiny rings. Depending on which ring the light enters first, it will either pass in the forward direction or be dissipated in the backward direction, making for one-way transmission. The rings can be tuned by heating them using a "microheater," which changes the wavelengths at which they transmit, making it possible to handle a broad frequency range.

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Mimicking the Brain -- In Silicon: New Computer Chip Models How Neurons Communicate With Each Other at Synapses

Mimicking the Brain -- In Silicon: New Computer Chip Models How Neurons Communicate With Each Other at Synapses

  1:39:00 PM    Science Lover

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For decades, scientists have dreamed of building computer systems that could replicate the human BRAIN's talent for learning new tasks.

Researchers have taken a major step toward that goal by designing a computer chip that mimics how the brain's neurons adapt in response to new information. (Credit: MIT)

MIT researchers have now taken a major step toward that goal by designing a computer chip that mimics how the brain's neurons adapt in response to new information. This phenomenon, known as plasticity, is believed to underlie many brain functions, including learning and memory.

With about 400 transistors, the silicon chip can simulate the activity of a single brain synapse -- a connection between two neurons that allows information to flow from one to the other. The researchers anticipate this chip will help neuroscientists learn much more about how the brain works, and could also be used in neural prosthetic devices such as artificial retinas, says Chi-Sang Poon, a principal research scientist in the Harvard-MIT Division of Health Sciences and Technology.

Poon is the senior author of a paper describing the chip in the Proceedings of the National Academy of Sciences the week of Nov. 14. Guy Rachmuth, a former postdoc in Poon's lab, is lead author of the paper. Other authors are Mark Bear, the Picower Professor of Neuroscience at MIT, and Harel Shouval of the University of Texas Medical School.

Modeling synapses

There are about 100 billion neurons in the brain, each of which forms synapses with many other neurons. A synapse is the gap between two neurons (known as the presynaptic and postsynaptic neurons). The presynaptic neuron releases neurotransmitters, such as glutamate and GABA, which bind to receptors on the postsynaptic cell membrane, activating ion channels. Opening and closing those channels changes the cell's electrical potential. If the potential changes dramatically enough, the cell fires an electrical impulse called an action potential.

All of this synaptic activity depends on the ion channels, which control the flow of charged atoms such as sodium, potassium and calcium. Those channels are also key to two processes known as long-term potentiation (LTP) and long-term depression (LTD), which strengthen and weaken synapses, respectively.

The MIT researchers designed their computer chip so that the transistors could mimic the activity of different ion channels. While most chips operate in a binary, on/off mode, current flows through the transistors on the new brain chip in analog, not digital, fashion. A gradient of electrical potential drives current to flow through the transistors just as ions flow through ion channels in a cell.

"We can tweak the parameters of the circuit to match specific ion channels," Poon says. "We now have a way to capture each and every ionic process that's going on in a neuron."

Previously, researchers had built circuits that could simulate the firing of an action potential, but not all of the circumstances that produce the potentials. "If you really want to mimic brain function realistically, you have to do more than just spiking. You have to capture the intracellular processes that are ion channel-based," Poon says.

The new chip represents a "significant advance in the efforts to incorporate what we know about the biology of neurons and synaptic plasticity onto CMOS [complementary metal-oxide-semiconductor] chips," says Dean Buonomano, a professor of neurobiology at the University of California at Los Angeles, adding that "the level of biological realism is impressive.

The MIT researchers plan to use their chip to build systems to model specific neural functions, such as the visual processing system. Such systems could be much faster than digital computers. Even on high-capacity computer systems, it takes hours or days to simulate a simple brain circuit. With the analog chip system, the simulation is even faster than the biological system itself.

Another potential application is building chips that can interface with biological systems. This could be useful in enabling communication between neural prosthetic devices such as artificial retinas and the brain. Further down the road, these chips could also become building blocks for artificial intelligence devices, Poon says.

Debate resolved

The MIT researchers have already used their chip to propose a resolution to a longstanding debate over how LTD occurs.

One theory holds that LTD and LTP depend on the frequency of action potentials stimulated in the postsynaptic cell, while a more recent theory suggests that they depend on the timing of the action potentials' arrival at the synapse.

Both require the involvement of ion channels known as NMDA receptors, which detect postsynaptic activation. Recently, it has been theorized that both models could be unified if there were a second type of receptor involved in detecting that activity. One candidate for that second receptor is the endo-cannabinoid receptor.

Endo-cannabinoids, similar in structure to marijuana, are produced in the brain and are involved in many functions, including appetite, pain sensation and memory. Some neuroscientists had theorized that endo-cannabinoids produced in the postsynaptic cell are released into the synapse, where they activate presynaptic endo-cannabinoid receptors. If NMDA receptors are active at the same time, LTD occurs.

When the researchers included on their chip transistors that model endo-cannabinoid receptors, they were able to accurately simulate both LTD and LTP. Although previous experiments supported this theory, until now, "nobody had put all this together and demonstrated computationally that indeed this works, and this is how it works," Poon says.

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Engineers Solve Longstanding Problem in Photonic Chip Technology: Findings Help Pave Way for Next Generation of Computer Chips

Engineers Solve Longstanding Problem in Photonic Chip Technology: Findings Help Pave Way for Next Generation of Computer Chips

  1:00:00 AM    Science Lover

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Stretching for thousands of miles beneath oceans, optical fibers now connect every continent except for Antarctica. With less data loss and higher bandwidth, optical-fiber technology allows information to zip around the world, bringing pictures, video, and other data from every corner of the globe to your computer in a split second. But although optical fibers are increasingly replacing copper wires, carrying information via photons instead of electrons, today's computer technology still relies on electronic chips.

Caltech engineers have developed a new way to 
isolate light on a photonic chip, allowing light to 
travel in only one direction. This finding can lead 
to the next generation of computer-chip technology: 
photonic chips that allow for faster computers 
and less data loss. (Credit: Caltech/Liang Feng)

Now, researchers led by engineers at the California Institute of Technology (Caltech) are paving the way for the next generation of computer-chip technology: photonic chips. With integrated circuits that use light instead of electricity, photonic chips will allow for faster computers and less data loss when connected to the global fiber-optic network.

"We want to take everything on an electronic chip and reproduce it on a photonic chip," says Liang Feng, a postdoctoral scholar in electrical engineering and the lead author on a paper to be published in the August 5 issue of the journal Science. Feng is part of Caltech's nanofabrication group, led by Axel Scherer, Bernard A. Neches Professor of Electrical Engineering, Applied Physics, and Physics, and co-director of the Kavli Nanoscience Institute at Caltech.

In that paper, the researchers describe a new technique to isolate light signals on a silicon chip, solving a longstanding problem in engineering photonic chips.

An isolated light signal can only travel in one direction. If light weren't isolated, signals sent and received between different components on a photonic circuit could interfere with one another, causing the chip to become unstable. In an electrical circuit, a device called a diode isolates electrical signals by allowing current to travel in one direction but not the other. The goal, then, is to create the photonic analog of a diode, a device called an optical isolator. "This is something scientists have been pursuing for 20 years," Feng says.

Normally, a light beam has exactly the same properties when it moves forward as when it's reflected backward. "If you can see me, then I can see you," he says. In order to isolate light, its properties need to somehow change when going in the opposite direction. An optical isolator can then block light that has these changed properties, which allows light signals to travel only in one direction between devices on a chip.

"We want to build something where you can see me, but I can't see you," Feng explains. "That means there's no signal from your side to me. The device on my side is isolated; it won't be affected by my surroundings, so the functionality of my device will be stable."

To isolate light, Feng and his colleagues designed a new type of optical waveguide, a 0.8-micron-wide silicon device that channels light. The waveguide allows light to go in one direction but changes the mode of the light when it travels in the opposite direction.

A light wave's mode corresponds to the pattern of the electromagnetic field lines that make up the wave. In the researchers' new waveguide, the light travels in a symmetric mode in one direction, but changes to an asymmetric mode in the other. Because different light modes can't interact with one another, the two beams of light thus pass through each other.



Previously, there were two main ways to achieve this kind of optical isolation. The first way -- developed almost a century ago -- is to use a magnetic field. The magnetic field changes the polarization of light -- the orientation of the light's electric-field lines -- when it travels in the opposite direction, so that the light going one way can't interfere with the light going the other way. "The problem is, you can't put a large magnetic field next to a computer," Feng says. "It's not healthy."

The second conventional method requires so-called nonlinear optical materials, which change light's frequency rather than its polarization. This technique was developed about 50 years ago, but is problematic because silicon, the material that's the basis for the integrated circuit, is a linear material. If computers were to use optical isolators made out of nonlinear materials, silicon would have to be replaced, which would require revamping all of computer technology. But with their new silicon waveguides, the researchers have become the first to isolate light with a linear material.

Although this work is just a proof-of-principle experiment, the researchers are already building an optical isolator that can be integrated onto a silicon chip. An optical isolator is essential for building the integrated, nanoscale photonic devices and components that will enable future integrated information systems on a chip. Current, state-of-the-art photonic chips operate at 10 gigabits per second (Gbps) -- hundreds of times the data-transfer rates of today's personal computers -- with the next generation expected to soon hit 40 Gbps. But without built-in optical isolators, those chips are much simpler than their electronic counterparts and are not yet ready for the market. Optical isolators like those based on the researchers' designs will therefore be crucial for commercially viable photonic chips.

In addition to Feng and Scherer, the other authors on the Science paper, "Non-reciprocal light propagation in a silicon photonic circuit," are Jingqing Huang, a Caltech graduate student; Maurice Ayache of UC San Diego and Yeshaiahu Fainman, Cymer Professor in Advanced Optical Technologies at UC San Diego; and Ye-Long Xu, Ming-Hui Lu, and Yan-Feng Chen of the Nanjing National Laboratory of Microstructures in China. This research was done as part of the Center for Integrated Access Networks (CIAN), one of the National Science Foundation's Engineering Research Centers. Fainman is also the deputy director of CIAN. Funding was provided by the National Science Foundation, and the Defense Advanced Research Projects Agency.

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World's first Content Addressable Memory stores data without using power

World's first Content Addressable Memory stores data without using power

  9:59:00 PM    Science Lover

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NEC Corporation and Tohoku University announced today the development of the world's first content addressable memory (CAM) that both maintains the same high operation speed and non-volatile operation as existing circuits when processing and storing data on a circuit while power is off.

NEC's new CAM is a part of spintronics logic integrated circuit technologies that utilize the negative properties of electrons together with the spin magnetic moment. The new CAM utilizes the vertical magnetization of vertical domain wall elements in reaction to magnetic substances in order to enable data that is processing within the CAM to be stored on a circuit without using power. This contrasts to conventional technologies that required data to be stored within memory. As a result, data can be saved on circuits even when power is cut from the CAM.

In recent years, the use of ICT equipment has steadily increased due to the widespread growth of cloud computing. Most existing equipment requires a short amount of time to get started and internal circuits remain active when the equipment is in standby mode. Therefore, the growing consumption of power by ICT equipment in standby mode has become a serious concern.

Use of the new CAM in combination with existing nonvolatile memory is related to greater non-volatility of CPU for electronics and other storage devices. Furthermore, use of this new CAM enables the development of electronics that start instantly and consume zero electricity while in standby mode.

Key features of these newly developed technologies:

• High-speed data retrieval

In order for CAM to be both nonvolatile and maintain a high speed, two spintronics devices, spinning in opposite directions to one another, were connected within the same cell. In terms of constructing the circuit, writing is done once by connecting two devices in a series using recently developed three pin particles that separate the current path into writing and reading.

This new process enables cells to become more compact since the number of writing switches per element is reduced by one. Moreover, the new CAM achieve the same level of high-speed data retrieval as current CMOS based CAM that feature 5ns and low power consumption of 9.4mW.

• Approximately half the circuit area in comparison to existing technologies
In addition to the vertical domain wall element can connect in series by separating the route of current into reading and writing, the newly developed CAM circuit technologies can reduce the number of transistors from eight to three in every two cells by sharing transistors. This results in a 50% CAM area reduction.

NEC developed nonvolatile particles aiming for both greater convenience and energy conservation. Additionally, NEC and Tohoku University developed a simulation technology for a circuit diagram including spintronics particles in parallel with designing technologies for massively large integrated circuits for developments involving the most advanced spintronics logic integrated circuits.

NEC and Tohoku University will announce their latest results on June 17 at VLSI Circuit Symposium 2011 (June 13-17, Kyoto).

Provided by NEC

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Semiconductor Could Turn Heat Into Computing Power

Semiconductor Could Turn Heat Into Computing Power

  9:59:00 AM    Science Lover

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Computers might one day recycle part of their own waste heat, using a material being studied by researchers at Ohio State University.

The material is a semiconductor called gallium manganese arsenide. In the early online edition of Nature Materials, researchers describe the detection of an effect that converts heat into a quantum mechanical phenomenon – known as spin – in a semiconductor.

Once developed, the effect could enable integrated circuits that run on heat, rather than electricity.

Roberto Myers

This research merges two cutting-edge technologies: thermo-electricity and spintronics, explained team leaders Joseph Heremans, Ohio Eminent Scholar in Nanotechnology, and Roberto Myers, assistant professor of materials science and electrical engineering at Ohio State University.

Joseph Heremans

Researchers around the world are working to develop electronics that utilize the spin of electrons to read and write data. So-called “spintronics” are desirable because in principle they could store more data in less space, process data faster, and consume less power.

Myers and Heremans are trying to combine spintronics with thermo-electronics – that is, devices that convert heat to electricity.

The hybrid technology, “thermo-spintronics,” would convert heat to electron spin.

In so doing, thermo-spintronics could solve two problems for the computing industry: how to remove waste heat, and how to boost computing power without creating more heat.

“Spintronics is considered as a possible basis for new computers in part because the technology is claimed to produce no heat. Our measurements shed light on the thermodynamics of spintronics, and may help address the validity of this claim,” Heremans said.

In fact, as the electronics industry tries to build smaller, denser computer circuits, a main limiting factor is the heat those circuits produce, said Myers.

“All of the computers we have now could actually run much faster than they do, but they’re not allowed to – because if they did, they would fail after a short time,” Myers said. “So a huge amount of money in the semiconductor industry is put toward thermal management.”

In one possible use of thermo-spintronics, a device could sit atop a traditional microprocessor, and siphon waste heat away to run additional memory or computation. Myers noted that such applications are still a long way off.

The researchers studied how heat can be converted to spin polarization– an effect called the spin-Seebeck effect. It was first identified by researchers at Tohoku University and reported in a 2008 paper in the journal Nature. Those researchers detected the effect in a piece of metal, rather than a semiconductor.

The new measurements, carried out by team member Christopher Jaworski, doctoral student of mechanical engineering at Ohio State, provide the first independent verification of the effect in a semiconductor material called gallium manganese arsenide.

While gallium arsenide is a semiconductor used in cell phones today, the addition of the element manganese endows the material with magnetic properties.

Samples of this material were carefully prepared into thin single-crystal films by collaborators Shawn Mack and Professor David Awschalom at the University of California at Santa Barbara, who also assisted with interpretation of the results. Jing Yang, doctoral student of materials science and engineering at Ohio State, then processed the samples for the experiment.

In this type of material, the spins of the charges line up parallel with the orientation of the sample’s overall magnetic field. So when the Ohio State researchers were trying to detect the spins of the electrons, they were really measuring whether the electrons in any particular area of the material were oriented as “spin-up” or “spin-down.”

In the experiment, they heated one side of the sample, and then measured the orientations of spins on the hot side and the cool side. On the hot side, the electrons were oriented in the spin-up direction, and on the cool side, they were spin-down.

The researchers also discovered, to their own surprise, that two pieces of the material do not need to be physically connected for the effect to propagate from one to the other.

They scraped away a portion of the sample with a file, to create two pieces of material separated by a tiny gap. If the spin effect were caused by electrical conduction – that is, electrons flowing from one part of the material to the other – then the gap would block the effect from spreading. Again, they applied heat to one side.

The effect persisted.

“We figured that each piece would have its own distribution of spin-up and spin-down electrons,” said Myers. “Instead, one side of the first piece was spin up, and the far side of the second piece was spin down. The effect somehow crossed the gap.”

“The original spin-Seebeck detection by the Tohoku group baffled all theoreticians,” Heremans added. “In this study, we’ve independently confirmed those measurements on a completely different material. We’ve proven we can get the same results as the Tohoku group, even when we take the measurements on a sample that’s been separated into two pieces, so that electrons couldn’t possibly pass between them.”

Despite these new experiments, the origin of the spin-Seebeck effect remains a mystery.

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Silicon Oxide Circuits Break BarrierNanocrystal Conductors Could Lead to Massive, Robust 3-D Storage

Silicon Oxide Circuits Break BarrierNanocrystal Conductors Could Lead to Massive, Robust 3-D Storage

  8:13:00 PM    Science Lover

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Rice University scientists have created the first two-terminal memory chips that use only silicon, one of the most common substances on the planet, in a way that should be easily adaptable to nanoelectronic manufacturing techniques and promises to extend the limits of miniaturization subject to Moore's Law.

A 1k silicon oxide memory has been assembled by Rice and a commercial partner as a proof-of-concept. Silicon nanowire forms when charge is pumped through the silicon oxide, creating a two-terminal resistive switch. (Credit: Images courtesy Jun Yao/Rice University)

Last year, researchers in the lab of Rice Professor James Tour showed how electrical current could repeatedly break and reconnect 10-nanometer strips of graphite, a form of carbon, to create a robust, reliable memory "bit." At the time, they didn't fully understand why it worked so well.

Now, they do. A new collaboration by the Rice labs of professors Tour, Douglas Natelson and Lin Zhong proved the circuit doesn't need the carbon at all.

Jun Yao, a graduate student in Tour's lab and primary author of the paper to appear in the online edition of Nano Letters, confirmed his breakthrough idea when he sandwiched a layer of silicon oxide, an insulator, between semiconducting sheets of polycrystalline silicon that served as the top and bottom electrodes.

Applying a charge to the electrodes created a conductive pathway by stripping oxygen atoms from the silicon oxide and forming a chain of nano-sized silicon crystals. Once formed, the chain can be repeatedly broken and reconnected by applying a pulse of varying voltage.

The nanocrystal wires are as small as 5 nanometers (billionths of a meter) wide, far smaller than circuitry in even the most advanced computers and electronic devices.

"The beauty of it is its simplicity," said Tour, Rice's T.T. and W.F. Chao Chair in Chemistry as well as a professor of mechanical engineering and materials science and of computer science. That, he said, will be key to the technology's scalability. Silicon oxide switches or memory locations require only two terminals, not three (as in flash memory), because the physical process doesn't require the device to hold a charge.

It also means layers of silicon-oxide memory can be stacked in tiny but capacious three-dimensional arrays. "I've been told by industry that if you're not in the 3-D memory business in four years, you're not going to be in the memory business. This is perfectly suited for that," Tour said.

Silicon-oxide memories are compatible with conventional transistor manufacturing technology, said Tour, who recently attended a workshop by the National Science Foundation and IBM on breaking the barriers to Moore's Law, which states the number of devices on a circuit doubles every 18 to 24 months.

"Manufacturers feel they can get pathways down to 10 nanometers. Flash memory is going to hit a brick wall at about 20 nanometers. But how do we get beyond that? Well, our technique is perfectly suited for sub-10-nanometer circuits," he said.

Austin tech design company PrivaTran is already bench testing a silicon-oxide chip with 1,000 memory elements built in collaboration with the Tour lab. "We're real excited about where the data is going here," said PrivaTran CEO Glenn Mortland, who is using the technology in several projects supported by the Army Research Office, National Science Foundation, Air Force Office of Scientific Research, and the Navy Space and Naval Warfare Systems Command Small Business Innovation Research (SBIR) and Small Business Technology Transfer programs.

"Our original customer funding was geared toward more high-density memories," Mortland said. "That's where most of the paying customers see this going. I think, along the way, there will be side applications in various nonvolatile configurations."

Yao had a hard time convincing his colleagues that silicon oxide alone could make a circuit. "Other group members didn't believe him," said Tour, who added that nobody recognized silicon oxide's potential, even though it's "the most-studied material in human history."

"Most people, when they saw this effect, would say, 'Oh, we had silicon-oxide breakdown,' and they throw it out," he said. "It was just sitting there waiting to be exploited."

In other words, what used to be a bug turned out to be a feature.

Yao went to the mat for his idea. He first substituted a variety of materials for graphite and found none of them changed the circuit's performance. Then he dropped the carbon and metal entirely and sandwiched silicon oxide between silicon terminals. It worked.

"It was a really difficult time for me, because people didn't believe it," Yao said. Finally, as a proof of concept, he cut a carbon nanotube to localize the switching site, sliced out a very thin piece of silicon oxide by focused ion beam and identified a nanoscale silicon pathway under a transmission electron microscope.

"This is research," Yao said. "If you do something and everyone nods their heads, then it's probably not that big. But if you do something and everyone shakes their heads, then you prove it, it could be big.

"It doesn't matter how many people don't believe it. What matters is whether it's true or not."

Silicon-oxide circuits carry all the benefits of the previously reported graphite device. They feature high on-off ratios, excellent endurance and fast switching (below 100 nanoseconds).

They will also be resistant to radiation, which should make them suitable for military and NASA applications. "It's clear there are lots of radiation-hardened uses for this technology," Mortland said.

Silicon oxide also works in reprogrammable gate arrays being built by NuPGA, a company formed last year through collaborative patents with Rice University. NuPGA's devices will assist in the design of computer circuitry based on vertical arrays of silicon oxide embedded in "vias," the holes in integrated circuits that connect layers of circuitry. Such rewritable gate arrays could drastically cut the cost of designing complex electronic devices.

Zhengzong Sun, a graduate student in Tour's lab, was co-author of the paper with Yao; Tour; Natelson, a Rice professor of physics and astronomy; and Zhong, assistant professor of electrical and computer engineering.

The David and Lucille Packard Foundation, the Texas Instruments Leadership University Fund, the National Science Foundation, PrivaTran and the Army Research Office SBIR supported the research.

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Ultralow-power memory uses orders of magnitude less power than other devices

Ultralow-power memory uses orders of magnitude less power than other devices

  12:25:00 AM    Science Lover

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As RFID tags are becoming more widespread for tracking and identifying almost anything, researchers are continuing to develop cheap, ultralow-power memory devices for these applications. In a recent study, scientists from Cambridge have taken another step forward in this area by developing a write-once-read-many-times (WORM) memory device that requires just a fraction of the power needed by previous devices. In principle, the low-power memory can be used in any organic electronic circuit where the operation power is low.

The device structure and energy level diagram of the WORM
memory, which can be programmed at power densities that
are orders of magnitude lower than previously reported
ultralow-power WORM devices. Image credit: Wang, et al.
©2010 American Institute of Physics.

Read Full Article Here----

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Discovery Brings New Type Of Fast Computers Closer To Reality

Discovery Brings New Type Of Fast Computers Closer To Reality

  1:10:00 AM    Science Lover

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Physicists at UC San Diego have successfully created speedy integrated circuits with particles called “excitons” that operate at commercially cold temperatures, bringing the possibility of a new type of extremely fast computer based on excitons closer to reality.

Alex High and Aaron Hammack adjust the optics in their UCSD lab. (Credit: Image courtesy of University of California - San Diego)

  
Their discovery, detailed this week in the advance online issue of the journal Nature Photonics, follows the team’s demonstration last summer of an integrated circuit—an assembly of transistors that is the building block for all electronic devices—capable of working at 1.5 degrees Kelvin above absolute zero. That temperature, equivalent to minus 457 degrees Fahrenheit, is not only less than the average temperature of deep space, but achievable only in special research laboratories.

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