Chinese Quantum Satellite Sends ‘Unbreakable’ Code

China has sent an “unbreakablecode from a satellite to the Earth, marking the first time space-to-ground quantum key distribution technology has been realized, state media said. China launched the world’s first quantum satellite last August, to help establish “hack proofcommunications, a development the Pentagon has called a “notable advance“. The official Xinhua news agency said the latest experiment was published in the journal Nature, where reviewers called it a “milestone“.

The satellite sent quantum keys to ground stations in China between 645 km (400 miles) and 1,200 km (745 miles) away at a transmission rate up to 20 orders of magnitude more efficient than an optical fiber, Xinhua cited Pan Jianwei, lead scientist on the experiment from the state-run Chinese Academy of Sciences, as saying.

That, for instance, can meet the demand of making an absolute safe phone call or transmitting a large amount of bank data,” Pan said. Any attempt to eavesdrop on the quantum channel would introduce detectable disturbances to the system, Pan said. “Once intercepted or measured, the quantum state of the key will change, and the information being intercepted will self-destruct,” Xinhua said.

The news agency said there were “enormous prospects” for applying this new generation of communications in defense and finance.


Quantum Satellite Secures Communications

A Chinese quantum satellite has dispatched transmissions over a distance of 1,200 km (746 miles), a dozen times further than the previous record, a breakthrough in a technology that could be used to deliver secure messages, state media said on Friday.

China launched the world’s first quantum satellite last August, to help establish “hack proof” communications between space and the ground, state media said at the time.

The feat opens up “bright prospects” for quantum communications, said Pan Jianwei, the lead scientist of the Chinese team, Quantum Experiments at Space Scale (QUESS), according to the official Xinhua news agency.

The scientists exploited the phenomenon of quantum entanglement, in which a particle can affect a far-off twin instantly, somehow overcoming the long distance separating them, a situation termed “spooky action at a distance” by the Nobel-prize winning physicist Albert Einstein, Xinhua added.

The team had successfully distributed entangled photon pairs over 1,200 km, it said, outstripping the distance of up to 100 km (62 miles) at which entanglement had previously been achieved.

The technology so far is “the only way to establish secure keys between two distant locations on earth without relying on trustful relay,” Pan told Xinhua, referring to encrypted messages.

The new development “illustrates the possibility of a future global quantum communication network” the journal Science, which published the results of the Chinese team, said on its website.


Solar Power : Quantum Dots Versus Nanowires

A trio of researchers at North Dakota State University, Fargo, and the University of South Dakota have turned to computer modeling to help decide which of two competing materials should get its day in the sun as the nanoscale energy-harvesting technology of future solar panelsquantum dots or nanowires. Andrei Kryjevski and his colleagues, Dimitri Kilin and Svetlana Kilina, report in AIP Publishing’s Journal of Renewable and Sustainable Energy that they used computational chemistry models to predict the electronic and optical properties of three types of nanoscale (billionth of a meter) silicon structures with a potential application for solar energy collection: a quantum dot, one-dimensional chains of quantum dots and a nanowire. The ability to absorb light is substantially enhanced in nanomaterials compared to those used in conventional semiconductors. Determining which form — quantum dots or nanowire — maximizes this advantage was the goal of the numerical experiment conducted by the three researchers.nanowires
Amorphous Silicon nanowire (yellow network) facilitates harvesting of solar energy in the form of a photon (wavy line). In the process of light absorption a pair of mobile charge carriers is created (red clouds depict an electron smeared in space, while the blue clouds visualize the so-called hole which is a positively charged carrier). The energy of their directed motion is then transformed into electricity.
We used Density Functional Theory, a computational approach that allows us to predict electronic and optical properties that reflect how well the nanoparticles can absorb light, and how that effectiveness is affected by the interaction between quantum dots and the disorder in their structures,” Kryjevski said. “This way, we can predict how quantum dots, quantum dot chains and nanowires will behave in real life even before they are synthesized and their working properties experimentally checked.

How To Build A Nanocomputer Using Graphene

A team of researchers from the University of California, Riverside’s Bourns College of Engineering, led by Alexander Balandin and Roger Lake, have greatly facilitate the use of graphene in electronic devices. A transistor implemented with graphene will be very fast but will suffer from leakage currents and power dissipation while in the off state because of the absence of the energy band gap. Efforts to induce a band-gap in graphene via quantum confinement or surface functionalization have not resulted in a breakthrough. Now, thanks to the University of California Riverside team findings, graphene applications in electronic circuits for information processing are feasible.

Graphene is a single-atom thick carbon crystal with unique properties beneficial for electronics including extremely high electron mobility and phonon thermal conductivity. However, graphene does not have an energy band gap, which is a specific property of semiconductor materials that separate electrons from holes and allows a transistor implemented with a given material to be completely switched off

Most researchers have tried to change graphene to make it more like conventional semiconductors for applications in logic circuits,” Balandin said. “This usually results in degradation of graphene properties. For example, attempts to induce an energy band gap commonly result in decreasing electron mobility while still not leading to sufficiently large band gap.
We decided to take alternative approach,” Balandin said. “Instead of trying to change graphene, we changed the way the information is processed in the circuits.”


Researchers Control Movements Of Molecular Motor

An international team of scientists has taken the next step in creating nanoscale machines by designing a multi-component molecular motor that can be moved clockwise and counterclockwise. It’s an essential step in creating nanoscale devices—quantum machines that operate on different laws of physics than classical machines—that scientists envision could be used for everything from powering quantum computers to sweeping away blood clots in arteries.
Although researchers can rotate or switch individual molecules on and off, the new study is the first to create a stand-alone molecular motor that has multiple parts, said Saw-Wai Hla, an Ohio University professor of physics and astronomy who led the study with french researcher Christian Joachim (CEMES/CNRS) working with A*Star in Singapore and in France Gwenael Rapenne of CEMES/CNRS.

This illustration shows the structure of the molecular motors.
In the study, published in Nature Nanotechnology, the scientists demonstrated that they could control the motion of the motor with energy generated by electrons from a scanning tunneling microscope tip. The motor is about 2 nanometers in length and 1 nanometer high and was constructed on a gold crystal surface.
See other recent research by a Dutch team in this post:
Others researches: AND


From Firefly To Nanotechnology

What do fireflies, nanorods and Christmas lights have in common? Someday, consumers may be able to purchase multicolor strings of light that don’t need electricity or batteries to glow. Scientists in Syracuse University's College of Arts and Sciences found a new way to harness the natural light produced by fireflies (called bioluminescence) using nanoscience. Their breakthrough produces a system that is 20 to 30 times more efficient than those produced during previous experiments.
t’s all about the size and structure of the custom, quantum nanorods, which are produced in the laboratory by Mathew Maye, assistant professor of chemistry in SU’s College of Arts and Sciences; and Rabeka Alam, a chemistry Ph.D. candidate. Maye is also a member of the Syracuse Biomaterials Institute.

Firefly light is one of nature’s best examples of bioluminescence,” Maye says. “The light is extremely bright and efficient. We’ve found a new way to harness biology for nonbiological applications by manipulating the interface between the biological and nonbiological components.


Towards the nanocomputer

The narrowest conducting wires in silicon ever produced are shown to have the same electric current arrying capability as copper. This means electrical interconnects in silicon can be shrunk to the atomic-scale without losing their functionality – Ohm's law holds true at the atomic-scale. The University of New South Wales  (UNSW) researchers will use these wires to address individual atoms – a key step in realising a scalable nanocomputer."Interconnecting wiring of this scale will be vital for the development of future atomic-scale electronic circuits," says the lead author of the study, Bent Weber, a PhD student in the ARC Centre of Excellence for Quantum Computation and Communication Technology at UNSW, in Sydney, Australia, supervised by Dr Michelle Simmmons.

Driven by the semiconductor industry, computer chip components continuously shrink in size allowing ever smaller and more powerful computers,” Simmons says. Over the past 50 years this paradigm has established the microelectronics industry as one of the key drivers for global economic growth.  A major focus of the Centre of Excellence at UNSW is to push this technology to the next level to develop a silicon-based nanocomputer, where single atoms serve as the individual units of computation,” she says. “It will come down to the wire. We are on the threshold of making transistors out of individual atoms. But to build a practical quantum computer we have recognised that the interconnecting wiring and circuitry also needs to shrink to the atomic scale.”


The wires were made by precisely placing chains of phosphorus atoms within a silicon crystal, according to the study, which includes researchers from the University of Melbourne and Purdue University in the US.

Photonic chip paves the way to quantum processors

Researchers from Bristol University in Great Britain, who have been developing quantum photonic chips for the past six years, are now working on scaling up the complexity of this device, and see this technology as the building block for the quantum computers of the future.In order to build a quantum computer, we not only need to be able to control complex phenomena such as entanglement and mixture, but we need to be able to do this on a chip, in much the same way as the modern computers we have today,” says Professor Jeremy O'Brien, Director of the Centre for Quantum Photonics.Our device enables this and we believe it is a major step forward towards optical quantum computing.”

“It isn’t ideal if your quantum computer can only perform a single specific task”, explains Peter Shadbolt, lead author of the study, which is published in the journal Nature Photonics.  “We would prefer to have a reconfigurable device which can perform a broad variety of tasks, much like our desktop PCs today – this reconfigurable ability is what we have now demonstrated. This device is approximately ten times more complex than previous experiments using this technology.