New technology may double radio frequency data capacity

CoSMIC (Columbia high-Speed and Mm-wave IC) Lab full-duplex transceiver IC that can be implemented in nanoscale CMOS to enable simultaneous transmission and reception at the same frequency in a wireless radio

A team of Columbia Engineering researchers has invented a technology -- full-duplex radio integrated circuits (ICs) -- that can be implemented in nanoscale CMOS to enable simultaneous transmission and reception at the same frequency in a wireless radio. Up to now, this has been thought to be impossible: transmitters and receivers either work at different times or at the same time but at different frequencies. The Columbia team, led by Electrical Engineering Associate Professor Harish Krishnaswamy, is the first to demonstrate an IC that can accomplish this. The researchers presented their work at the International Solid-State Circuits Conference (ISSCC) in San Francisco on February 25.

"This is a game-changer," says Krishnaswamy. "By leveraging our new technology, networks can effectively double the frequency spectrum resources available for devices like smartphones and tablets."
In the era of Big Data, the current frequency spectrum crisis is one of the biggest challenges researchers are grappling with and it is clear that today's wireless networks will not be able to support tomorrow's data deluge. Today's standards, such as 4G/LTE, already support 40 different frequency bands, and there is no space left at radio frequencies for future expansion. At the same time, the grand challenge of the next-generation 5G network is to increase the data capacity by 1,000 times.
So the ability to have a transmitter and receiver re-use the same frequency has the potential to immediately double the data capacity of today's networks. Krishnaswamy notes that other research groups and startup companies have demonstrated the theoretical feasibility of simultaneous transmission and reception at the same frequency, but no one has yet been able to build tiny nanoscale ICs with this capability.
"Our work is the first to demonstrate an IC that can receive and transmit simultaneously," he says. "Doing this in an IC is critical if we are to have widespread impact and bring this functionality to handheld devices such as cellular handsets, mobile devices such as tablets for WiFi, and in cellular and WiFi base stations to support full duplex communications."
The biggest challenge the team faced with full duplex was canceling the transmitter's echo. Imagine that you are trying to listen to someone whisper from far away while at the same time someone else is yelling while standing next to you. If you can cancel the echo of the person yelling, you can hear the other person whispering.
"If everyone could do this, everyone could talk and listen at the same time, and conversations would take half the amount of time and resources as they take right now," explains Jin Zhou, Krishnaswamy's PhD student and the paper's lead author. "Transmitter echo or 'self-interference' cancellation has been a fundamental challenge, especially when performed in a tiny nanoscale IC, and we have found a way to solve that challenge."
Krishnaswamy and Zhou plan next to test a number of full-duplex nodes to understand what the gains are at the network level. "We are working closely with Electrical Engineering Associate Professor Gil Zussman's group, who are network theory experts here at Columbia Engineering," Krishnaswamy adds. "It will be very exciting if we are indeed able to deliver the promised performance gains."

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Story Source:
The above story is based on materials provided by Columbia University School of Engineering and Applied Science. Note: Materials may be edited for content and length.

Wormhole Time Travel 'Possible' (If You're a Photon) | sci-english.blogspot.com

Time travel? | sci-english.blogspot.com

The idea of traversable wormholes has been science fiction fodder since Einstein first theorized their existence with the formulation of his general theory of relativity, but do wormholes even exist in nature? Actually, we have no idea if they exist or not, but if they do, theoretical physicists have proposed that they could act as portals into the future and the past or connect two distant regions of space.

But before you grab your Grays Sports Almanac and get ready for some temporal mischief, there’s one huge caveat to this idea — only photons may travel… and even photons may be too much of a stretch for the hypothetical shortcut through spacetime.

In a paper published to the arXiv preprint service (and submitted to the journal Physical Review D), theoretical physicist Luke Butcher of the University of Cambridge has revisited wormhole theory and potentially found a way to bridge these notoriously unstable entities.
In the late 1980s, physicist Kip Thorne, of the California Institute of Technology (Caltech), theorized that to make a wormhole ‘traversable’ — as in to actually make these spacetime shortcuts stable enough to travel through — some form of negative energy would be required. In the quantum world, this negative energy could come in the form of Casimir energy.
It is well known that if two perfectly smooth plates are held very close together in a vacuum, quantum effects between the plates will have a net repulsive (or attractive, depending on the plate configuration) effect between the two. This is caused by waves of energy being too large to fit between the plates, causing a net negative energy between the plates when compared with the surrounding “normal” space.
As realized by Thorne and his Caltech team, this Casimir energy could be applied to the neck of a wormhole, potentially holding it open long enough for something to pass through.

Alas, we are talking about quantum-sized wormhole throats, meaning Marty McFly’s speeding DeLorean will be left revving in the 1985 parking lot, unable to squeeze through. But even if some quantum-sized traveler could pass through the wormhole’s neck, the wormhole would still likely collapse very quickly.
On reevaluating this scenario, Butcher has identified some more stable wormhole configurations and, in certain situations, the wormhole collapse could be prevented for an “arbitrarily long time.” But for this to happen, the wormhole needs to be very long and have a very narrow throat. In this case it seems possible that photons could traverse the wormhole.
“(T)he negative Casimir energy does allow the wormhole to collapse extremely slowly, its lifetime growing without bound as the throat-length is increased,” writes Butcher. “We find that the throat closes slowly enough that its central region can be safely traversed by a pulse of light.”
Butcher admits that although it’s not clear from his calculations whether the light pulse will be able to complete its journey from one end to the other, there is a tantalizing possibility for sending signals faster than the speed of light or even back in time.

“These results tentatively suggest that a macroscopic traversable wormhole might be sustained by its own Casimir energy, providing a mechanism for faster-than-light communication and closed causal curves.”
For the moment, this work is highly theoretical, but, as pointed out by Matt Visser of Victoria University of Wellington, New Zealand, in New Scientist on Tuesday, this research could renew interest in the study of wormholes and their potential spacetime-bridging capabilities.
So if we were to look for physical evidence of wormholes, could this research help us? Could we perhaps look out for be some kind of unique polarization of light that has traveled from another part of the Universe or some other time, appearing randomly in our local volume of spacetime? For answers to these questions, and as to whether this may spawn some kind of faster-then-light communications technology, we’ll likely have to wait until the theoretical physicists have crunched more numbers.

Feathers in flight inspire anti-turbulence technology | sci-english.blogspot.com

The prototype anti-turbulence system developed at RMIT University, in wind tunnel tests | sci-english.blogspot.com

Inspired by nature's own anti-turbulence devices -- feathers -- researchers have developed an innovative system that could spell the end of turbulence on flights.

Researchers from the Unmanned Systems Research Team at RMIT University in Melbourne, Australia, have lodged a provisional patent on the system, which mimics the way feathers help birds detect disturbances in the air.
Research supervisor Professor Simon Watkins, said flight testing on a micro plane showed the system significantly reduced the effects of turbulence.
"By sensing gusts and disturbances in air flow through their feathers, birds are able to fly gracefully rather than bouncing around in turbulent air," he said.
"The system we have developed replicates this natural technology, with the aim of enabling planes to fly smoothly through even severe turbulence -- just like birds."
The system is based on the concept of phase-advanced sensing, in which flow disturbance is sensed before it results in aircraft movement.
This can be achieved by early sensing of the pressures from gust effects on the leading parts of the wing or by measuring the gusts ahead of the wing.
Professor Watkins said the system had great potential for all sizes of aircraft and could not only reduce the effects of turbulence on passengers but also reduce loads on plane wings, leading to lower fatigue and hence longer life.
"While we need to explore new sensor arrangements to apply this technology to larger and faster aircraft, we have proven the idea on the most challenging problem of keeping small, lightweight planes steady -- since these are the ones that get bounced around the most," he said.
The patent submission for a turbulence mitigation system for aircraft represents the successful outcome of PhD research by Abdulghani Mohamed, supervised by Professor Watkins and Dr Reece Clothier in RMIT's School of Aerospace, Mechanical and Manufacturing Engineering.
Mr Mohamed's theoretical contributions in the field of turbulence and its effects on flight vehicles, aided the development of this invention.
Video: http://www.youtube.com/watch?v=uflUmBbdaAo&feature=youtu.be

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Story Source:
The above story is based on materials provided by RMIT University. Note: Materials may be edited for content and length.

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Journal Reference:

1. A. Mohamed, S. Watkins, R. Clothier, M. Abdulrahim, K. Massey, R. Sabatini. Fixed-wing MAV attitude stability in atmospheric turbulence—Part 2: Investigating biologically-inspired sensors. Progress in Aerospace Sciences, 2014; 71: 1 DOI: 10.1016/j.paerosci.2014.06.002

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A novel platform for future spintronic technologies | sci-english

A novel platform for future spintronic technologies

Source: Ecole Polytechnique Fédérale de Lausanne
Summary: Spintronics is a new field of electronics, using electron spin rather than charge. Scientists have now shown that a conventional electrical insulator can be used as an optimal spintronic device.

Spintronics is an emerging field of technology where devices work by manipulating the spin of electrons rather than their charge. The field can bring significant advantages to computer technology, combining higher speeds with lower energy consumption. Spintronic circuits need ways to control electron spin without interference from electron charge. Scientists at EPFL, working with Université Paris-Sud and Paul Scherrer Institut, have discovered that a common insulating material behaves as a perfect spintronic conductor because it is not affected by background electron charge. In addition, the material's properties make it an ideal platform for directly observing a strange subatomic particle that could one day lead to a different, more stable type of quantum computers.

Spintronics
Spintronics (spin-transport or spin-based electronics) is a technology that exploits a quantum property of electrons called spin. Although difficult to describe in everyday terms, electron spin can be loosely compared to the rotation of a planet or a spinning top around its axis. Spin exists in either of two directions: "up" or "down," which can be described respectively as the clockwise or counter-clockwise rotation of the electron around its axis. Ultimately, spin is what gives electrons their magnetic properties, influencing the way they behave when they enter a magnetic field.
The different directions of electron spin can be used to encode information, much like the binary code used in digital communication. Spintronics can therefore open up a new generation of devices that combine conventional microelectronics with spin-dependent effects, overcoming the limitations of today's electronics like speed and energy consumption. The main challenge is being able to actually control electron spin, turning "up" or "down" as needed. This can be achieved with certain materials, but the problem is that these are often susceptible to interference from the charge of electrons.
An ideal material for spintronics
The team of Hugo Dil at EPFL, working with scientists from Paris and the PSI, has shown that a transparent insulating material, which normally does not conduct electrical charge, shows spin-dependent properties. The scientists used a method called SARPES, which has been perfected by Hugo Dil's group. The data showed that the electron gas at the surface of strontium titanate (SrTiO3) is spin-polarized, which means that it could be used to control the spin of electrons.
"This is interesting because it is the first evidence of a large spin polarization effect on a truly insulating substrate," says Hugo Dil. The discovery has significant implications for the future of spintronics, because it can lead to the development of spin-polarized materials that are not susceptible to interference from non spin-polarized electrical charge, allowing for finer and better control of electron spin.
A new particle for a different kind of quantum computer
Beyond spintronics, this insulating material might also be important for quantum computing, as it could be used to directly observe an elusive, strange particle called the Majorana fermion. This particle is unique because it actually is its own antiparticle as well. Sometimes referred to as the "ghost particle," the Majorana fermion has zero energy, zero moment, zero spin, and, so far, has never been observed unambiguously. In the future, Majorana fermions could become the foundation for a different kind of quantum computer that would, in theory, be exceptionally stable, as it would not be susceptible to external interference and noise.

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Story Source:
The above story is based on materials provided by Ecole Polytechnique Fédérale de Lausanne. Note: Materials may be edited for content and length.

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Journal Reference:

1. A. F. Santander-Syro, F. Fortuna, C. Bareille, T. C. Rödel, G. Landolt, N. C. Plumb, J. H. Dil, M. Radović. Giant spin splitting of the two-dimensional electron gas at the surface of SrTiO3. Nature Materials, 2014; DOI: 10.1038/nmat4107

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