Quantum Computers Coming Soon?

Mar. 21, 2013 — Researchers with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) have once again demonstrated the incredible capabilities of metamaterials -- artificial nanoconstructs whose optical properties arise from their physical structure rather than their chemical composition. Engineering a unique two-dimensional sheet of gold nanoantennas, the researchers were able to obtain the strongest signal yet of the photonic spin Hall effect, an optical phenomenon of quantum mechanics that could play a prominent role in the future of computing.


"With metamaterial, we were able to greatly enhance a naturally weak effect to the point where it was directly observable with simple detection techniques," said Xiang Zhang, a faculty scientist with Berkeley Lab's Materials Sciences Division who led this research. "We also demonstrated that metamaterials not only allow us to control the propagation of light but also allows control of circular polarization. This could have profound consequences for information encoding and processing."
The spin Hall effect, named in honor of physicist Edwin Hall, describes the curved path that spinning electrons follow as they move through a semiconductor. The curved movement arises from the interaction between the physical motion of the electron and its spin -- a quantized angular momentum that gives rise to magnetic moment. Think of a baseball pitcher putting spin on a ball to make it curve to the left or right.
"Light moving through a metal also displays the spin Hall effect but the photonic spin Hall effect is very weak because the spin angular momentum of photons and spin-orbit interactions are very small," says Xiaobo Yin, a member of Zhang's research group and the lead author of the Science paper. "In the past, people have managed to observe the photonic spin Hall effect by generating the process over and over again to obtain an accumulative signal, or by using highly sophisticated quantum measurements. Our metamaterial makes the photonic spin Hall effect observable even with a simple camera."
Metamaterials have garnered a lot of attention in recent years because their unique structure affords electromagnetic properties unattainable in nature. For example, a metamaterial can have a negative index of refraction, the ability to bend light backwards, unlike all materials found in nature, which bend light forward. Zhang, who holds the Ernest S. Kuh Endowed Chair Professor of Mechanical Engineering at the University of California (UC) Berkeley, where he also directs the National Science Foundation's Nano-scale Science and Engineering Center, has been at the forefront of metamaterials research. For this study, he and his group fashioned metamaterial surfaces about 30 nanometers thick (a human hair by comparison is between 50,000 and 100,000 nanometers thick). These metasurfaces were constructed from V-shaped gold nanoantennas whose geometry could be configured by adjusting the length and orientation of the arms of the Vs.
"We chose eight different antenna configurations with optimized geometry parameters to generate a linear phase gradient along the x direction," says Yin. "This enabled us to control the propagation of the light and introduce strong photon spin-orbit interactions through rapid changes in direction. The photonic spin Hall effect depends on the curvature of the light's trajectory, so the sharper the change in propagation direction, the stronger the effect."
Since the entire metasurface sample measured only 0.3 millimeters, a 50-millimeter lens was used to project the transmission of the light through the metamaterial onto a charge-coupled device (CCD) camera for imaging. From the CCD images, the researchers determined that both the control of light propagation and the giant photonic spin Hall effect were the direct results of the designed meta-material. This finding opens up a wealth of possibilities for new technologies.
"The controllable spin-orbit interaction and momentum transfer between spin and orbital angular momentum allows us to manipulate the information encoded on the polarization of light, much like the 0 and 1 of today's electronic devices," Yin says. "But photonic devices could encode more information and provide greater information security than conventional electronic devices."
Yin says the ability to control left and right circular polarization of light in metamaterial surfaces should allow for the formation of optical elements, like highly coveted "flat lenses," or the management of light polarization without using wave plates.
"Metamaterials provide us with tremendous design freedom that will allow us to modulate the strength of the photonic spin Hall effect at different spatial locations," Yin says. "We knew the photonic spin Hall effect existed in nature but it was so hard to detect. Now, with the right metamaterials we can not only enhance this effect we can harness it for our own purposes."

Arquitecto wrote:
Light propagating through a metamaterial follows a curved trajectory that drags light with different circular polarization in opposite transverse directions to produce a giant photonic Spin Hall effect. (Credit: Image courtesy of DOE/Lawrence Berkeley National Laboratory)

Mar. 21, 2013 — Researchers with the U.S. Department of Energy (DOE)'s Lawrence Berkeley National Laboratory (Berkeley Lab) have once again demonstrated the incredible capabilities of metamaterials -- artificial nanoconstructs whose optical properties arise from their physical structure rather than their chemical composition. Engineering a unique two-dimensional sheet of gold nanoantennas, the researchers were able to obtain the strongest signal yet of the photonic spin Hall effect, an optical phenomenon of quantum mechanics that could play a prominent role in the future of computing.


"With metamaterial, we were able to greatly enhance a naturally weak effect to the point where it was directly observable with simple detection techniques," said Xiang Zhang, a faculty scientist with Berkeley Lab's Materials Sciences Division who led this research. "We also demonstrated that metamaterials not only allow us to control the propagation of light but also allows control of circular polarization. This could have profound consequences for information encoding and processing."
The spin Hall effect, named in honor of physicist Edwin Hall, describes the curved path that spinning electrons follow as they move through a semiconductor. The curved movement arises from the interaction between the physical motion of the electron and its spin -- a quantized angular momentum that gives rise to magnetic moment. Think of a baseball pitcher putting spin on a ball to make it curve to the left or right.
"Light moving through a metal also displays the spin Hall effect but the photonic spin Hall effect is very weak because the spin angular momentum of photons and spin-orbit interactions are very small," says Xiaobo Yin, a member of Zhang's research group and the lead author of the Science paper. "In the past, people have managed to observe the photonic spin Hall effect by generating the process over and over again to obtain an accumulative signal, or by using highly sophisticated quantum measurements. Our metamaterial makes the photonic spin Hall effect observable even with a simple camera."
Metamaterials have garnered a lot of attention in recent years because their unique structure affords electromagnetic properties unattainable in nature. For example, a metamaterial can have a negative index of refraction, the ability to bend light backwards, unlike all materials found in nature, which bend light forward. Zhang, who holds the Ernest S. Kuh Endowed Chair Professor of Mechanical Engineering at the University of California (UC) Berkeley, where he also directs the National Science Foundation's Nano-scale Science and Engineering Center, has been at the forefront of metamaterials research. For this study, he and his group fashioned metamaterial surfaces about 30 nanometers thick (a human hair by comparison is between 50,000 and 100,000 nanometers thick). These metasurfaces were constructed from V-shaped gold nanoantennas whose geometry could be configured by adjusting the length and orientation of the arms of the Vs.
"We chose eight different antenna configurations with optimized geometry parameters to generate a linear phase gradient along the x direction," says Yin. "This enabled us to control the propagation of the light and introduce strong photon spin-orbit interactions through rapid changes in direction. The photonic spin Hall effect depends on the curvature of the light's trajectory, so the sharper the change in propagation direction, the stronger the effect."
Since the entire metasurface sample measured only 0.3 millimeters, a 50-millimeter lens was used to project the transmission of the light through the metamaterial onto a charge-coupled device (CCD) camera for imaging. From the CCD images, the researchers determined that both the control of light propagation and the giant photonic spin Hall effect were the direct results of the designed meta-material. This finding opens up a wealth of possibilities for new technologies.
"The controllable spin-orbit interaction and momentum transfer between spin and orbital angular momentum allows us to manipulate the information encoded on the polarization of light, much like the 0 and 1 of today's electronic devices," Yin says. "But photonic devices could encode more information and provide greater information security than conventional electronic devices."
Yin says the ability to control left and right circular polarization of light in metamaterial surfaces should allow for the formation of optical elements, like highly coveted "flat lenses," or the management of light polarization without using wave plates.
"Metamaterials provide us with tremendous design freedom that will allow us to modulate the strength of the photonic spin Hall effect at different spatial locations," Yin says. "We knew the photonic spin Hall effect existed in nature but it was so hard to detect. Now, with the right metamaterials we can not only enhance this effect we can harness it for our own purposes."

Since my Uni. field pretty much focuses on Nano-Quantam/Theo phys. a prospect laid upon our field such as this is equivalent to discovering the electron in cathode rays in his CRT or Maxwell with his wheel for conservation of energy. Simply put, if usage of Quantam computers will go far beyond the spinhall and with the more popular (funded) research of meta-materials, it will be mind-numbing to observe on the countless & delicious observations we can make through such a tool. In our campus, we use a nano-metre imaging scale in which we use to polarize (κ > √εrµr) chiral metamaterials that also exploit surface plasmons which are produced from the interaction of light with metal-dielectric materials and essentially apply a simple negative refractive index to transform metamaterial cloaking in celestial mechanical quantam polaritons in order to duplicate the original imaging scale, originally produced by the spinhall itself. It takes a great deal of formulae and a ridiculously complicated magnetic permeability (negative) just to even acoustically record the tetrahertz. If this project is further developed, double positive mediums to acquire bandgap oscillations and quantam sources, will be more efficiently sourced and observed by a quantam fold! So as snell stated "1sinθ1 = n2sinθ2" will just be propagated by a chenkov simplification formulae, like "1sinθ1" into anti-parallel phase velocities using a poynting vector. Its enough to make one sleepless from the mere thought of acquiring research into a digital (quantam ) observation conductive which can be planned out JUST by spatial resolutions!

There is a god

highburied wrote:Arq

Speak english ffs!

A couple paragraphs for dummies please?

Die Borussen wrote:how soon? will we be alive? thats the point

spanky wrote:arq: arent u a doctor?

Babun wrote:Arq
That's a super exciting development. Is there a raw estimation how many logical circuits would be possible on say 1cm³ ?
P.S. I still like the idea of DNA computing much more exciting:
http://www.livescience.com/28273-biological-computers-possible-using-dna.html

Graphene Joins the Race to Redefine the Ampere
May 12, 2013 — A new joint innovation by the National Physical Laboratory (NPL) and the University of Cambridge could pave the way for redefining the ampere in terms of fundamental constants of physics. The world's first graphene single-electron pump (SEP), described in a paper today in Nature Nanotechnology, provides the speed of electron flow needed to create a new standard for electrical current based on electron charge.
The international system of units (SI) comprises seven base units (the metre, kilogram, second, Kelvin, ampere, mole and candela). Ideally these should be stable over time and universally reproducible. This requires definitions based on fundamental constants of nature which are the same wherever you measure them.
The present definition of the Ampere, however, is vulnerable to drift and instability. This is not sufficient to meet the accuracy needs of present and certainly future electrical measurement. The highest global measurement authority, the Conférence Générale des Poids et Mesures, has proposed that the ampere be re-defined in terms of the electron charge.
The frontrunner in this race to redefine the ampere is the single-electron pump (SEP). SEPs create a flow of individual electrons by shuttling them in to a quantum dot -- a particle holding pen -- and emitting them one at a time and at a well-defined rate. The paper published today describes how a graphene SEP has been successfully produced and characterised for the first time, and confirms its properties are extremely well suited to this application.
A good SEP pumps precisely one electron at a time to ensure accuracy, and pumps them quickly to generate a sufficiently large current. Up to now the development of a practical electron pump has been a two-horse race. Tuneable barrier pumps use traditional semiconductors and have the advantage of speed, while the hybrid turnstile utilises superconductivity and has the advantage that many can be put in parallel. Traditional metallic pumps, thought to be not worth pursuing, have been given a new lease of life by fabricating them out of the world's most famous super-material -- graphene.
Previous metallic SEPs made of aluminium are very accurate, but pump electrons too slowly for making a practical current standard. Graphene's unique semimetallic two-dimensional structure has just the right properties to let electrons on and off the quantum dot very quickly, creating a fast enough electron flow -- at near gigahertz frequency -- to create a current standard. The Achillies heel of metallic pumps, slow pumping speed, has thus been overcome by exploiting the unique properties of graphene.
The scientist at NPL and Cambridge still need to optimise the material and make more accurate measurements, but today's paper marks a major step forward in the road towards using graphene to redefine the ampere.
The realisation of the ampere is currently derived indirectly from resistance or voltage, which can be realised separately using the quantum Hall effect and the Josephson Effect. A fundamental definition of the ampere would allow a direct realisation that National Measurement Institutes around the world could adopt. This would shorten the chain for calibrating current-measuring equipment, saving time and money for industries billing for electricity and using ionising radiation for cancer treatment.
Current, voltage and resistance are directly correlated. Because we measure resistance and voltage based on fundamental constants -- electron charge and Planck's constant -- being able to measure current would also allow us to confirm the universality of these constants on which many precise measurements rely.
Graphene is not the last word in creating an ampere standard. NPL and others are investigating various methods of defining current based on electron charge. But today's paper suggests graphene SEPs could hold the answer. Also, any redefinition will have to wait until the Kilogram has been redefined. This definition, due to be decided soon, will fix the value of electronic charge, on which any electron-based definition of the ampere will depend.
Today's paper will also have important implications beyond measurement. Accurate SEPs operating at high frequency and accuracy can be used to make electrons collide and form entangled electron pairs. Entanglement is believed to be a fundamental resource for quantum computing, and for answering fundamental questions in quantum mechanics.
Malcolm Connolly, a research associate based in the Semiconductor Physics group at Cambridge, says: "This paper describes how we have successfully produced the first graphene single-electron pump. We have work to do before we can use this research to redefine the ampere, but this is a major step towards that goal. We have shown that graphene outperforms other materials used to make this style of SEP. It is robust, easier to produce, and operates at higher frequency. Graphene is constantly revealing exciting new applications and as our understanding of the material advances rapidly, we seem able to do more and more with it."

Attosecond Physics Division wrote:Illustration of the directional proton emission in acetylene with a specific laser waveform. The superposition of vibrational modes, which are responsible for the selective bond breaking, results from a combination of laser excitation of the anti-symmetric CH stretching mode and excitation of the symmetric CH stretching mode through ionization steps. The ionization steps are indicated by a change in colour from green (neutral) over yellow (cation) to orange (dication).

Attasecond Physics Division wrote:chemical bonds between carbon and hydrogen atoms are amongst the strongest in nature and their selective breaking, in particular in symmetric molecules, is of interest to chemical synthesis and the development of new biologically active molecules. An international team of scientists has now demonstrated that ultrashort light pulses with perfectly controlled waveforms can selectively break C-H bonds in acetylene ions. The researchers demonstrated that a suitable choice of the laser-pulse waveform leads to breaking of the C-H bond on the left (or right) side of the symmetric H-C≡C-H molecule. The scientists propose that their results can be understood by a new quantum control mechanism based on light induced vibration.


Hydrocarbons play an important role in organic chemistry, combustion, and catalysis. Selective breaking of C-H-bonds, can further enable novel synthesis of molecular species with new functionalities and applications in medicine. Until now a method for breaking C-H bonds selectively in symmetric hydrocarbons did not exist. Prof. Ali Alnaser (American University of Sharjah, UAE), who spent his sabbatical in the division of Prof. Ferenc Krausz at the Max Planck Institute of Quantum Optics (MPQ) as part of the collaboration between MPQ, the King Saud University (KSU), and the Ludwig-Maximilians-Universität Munich (LMU), and a team of physicists led by Prof. Matthias Kling (LMU) used ultrashort laser pulses to solve this problem. An important ingredient in making the experiments successful was the use of a high repetition rate laser system with ten thousand pulses per second in the group of Prof. Ulf Kleineberg (LMU), whereby the measuring times could be reduced compared to so far available systems. Mechanistic insight into how the laser light interacts with the molecules is provided by a theoretical model developed in the group of Prof. Regina de Vivie-Riedle (LMU).
For their experimental studies, the researchers used acetylene (C2H2): In this molecule the two carbon atoms are strongly bound by three electron pairs, while the hydrogen atoms symmetrically terminate the linear molecule on both ends. The scientists exposed a supersonic jet of C2H2 molecules inside a so called reaction microscope to ultrashort laser pulses with duration of only 4 fs (1 fs = 10-15 seconds). These pulses, generated in the Laboratory for Attosecond Physics of Prof. Ferenc Krausz (MPQ, LMU), have infrared wavelengths and consist of only a few cycles. The waveform of the light waves was precisely measured for each laser shot interacting with the molecules. "As a result of the interaction with the light wave, the molecule fragments after its double ionization into a positively charged C2H+ ion and a proton, which are both detected with the reaction microscope.," says Prof. Ali Alnaser. Since acetylene is a symmetric molecule, the C-H bonds on both sides of the molecule typically break with equal probability. In their experiment however, the scientists found that the laser waveform provides a means to increase the probability that the left versus the right C-H bond breaks and vice versa.
Quantum dynamical simulations show the nature of the laser-molecule interaction. "The already known scheme, where molecular reactions are controlled by electron dynamics prepared with the light waveform via laser-induced coupling of electronic states, does not work in this case. We discovered a new quantum control pathway.," Prof. de Vivie-Riedle explains. According to her new model, the few cycle laser pulse initially excites a subset of vibrations of the molecule that are laser-active. One of these vibrations is the anti-symmetric stretching mode, where one CH bond is elongated while the other is shortened. When the laser pulse reaches its peak electric field, it removes an electron from the triple-bond of the CC group (the molecule ionizes). By this process additionally laser-inactive vibrational modes are populated. Among those modes is the symmetric CH stretching mode, where both H atoms move synchronously towards or away from the CC group. In the remainder of the laser pulse, the freed electron is accelerated back onto the molecular cation, removes a second electron and creates the acetylene dication, which rapidly dissociates into the proton and the C2H+ ion that are observed in the experiment.
"Independent excitation of vibrations of the molecule is insufficient to explain the experimental results. A prerequisite for the observed control is a quantum effect: the superposition of the symmetric and anti-symmetric stretching modes. As a consequence of that interference, a situation can be created where only one CH bond vibrates and the other one remains frozen.," explains Prof de Vivie-Riedle. "This type of shaking of the molecule leads to breaking of a particular CH bond. The laser waveform controls the direction into which the vibrational wave packet, which results from the superposition of the vibrational modes, moves once it is created on the acetylene dication.," adds Prof. Matthias Kling.
The researchers see the results of their studies as a proof-of-principle for a new quantum control mechanism. "The laser waveform control mechanism is very general and we foresee that it may be applied to other, more complex molecular processes.," says Prof. Ali Alnaser, who wants to continue research into this direction. He adds: "While we have excited the vibrations non-resonantly in our study, higher degrees of control can be reached with resonant excitation using ultrashort laser pulses in the mid-infrared. Such laser systems are currently being developed and pave the way to exploit the full potential of the new control scheme."

Tomwin Lannister wrote:Does any of this stuff help when tracking and hunting large game in wooded areas?