Delft University of Technology

World’s Smallest Drone Autopilot System Goes Open Source.

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The Lisa/S chip is 4 square-centimeters — about the same size as a Euro coin. But this 1.9-gram sliver of silicon includes everything you need to autopilot an aerial drone.

It’s the world’s smallest drone autopilot system — over 30 grams lighter than its predecessor — according to the chip’s designers at the Delft University of Technology in the Netherlands. And best of all, both the hardware and the software is open source, meaning anyone can copy and use it — for free.

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“The main reason we chose open source is that we want to make it available for society,” says the project’s leader, Bart Remes. He envisions open source drone technology enabling a wider range of civilian drone applications, from agriculture to search and rescue.

“Before, only the military had access to this type of technology,” he says. “My vision is that within a few years, every fireman [will have] a drone in his pocket.”

Remes says he’s been flying remote-controlled aircraft since he was six years old. About 10 years ago, as a student at Delft, he started building his own drones, attracted to the challenges of programming and electronics. It turned out that very small drones — called micro air vehicles, or MAVs — are a great way to teach aerospace engineering because they’re relatively cheap, safe and easy to program.

“At university, a lot of students are working in a compute simulation and never see the real world,” Remes says. “With MAVs, they get to see the real world.” His student work turned into a full-time job as the head of the university’s MAV Laboratory, which is responsible for projects like DelFly, a small wing-flapping drone that resembles a dragonfly.

 

The Lisa/S is the MAV Laboratory’s latest project. The chip’s software is based on Paparazzi, an open source drone autopilot system that’s been around since 2003. The real innovation is the hardware. The tiny chip packs in everything you need for an autopilot system, including a gyroscope, accelerometer, altimeter, GPS, and an ARM processor — the same sort of CPU you might find in your smartphone. The Lisa/S can be used with any type of drone, from quadcopters to fixed-wing systems, Remes says.

The one limitation, he says, is that it can’t provide a continuous data link to its operators. “For us, it’s not a limitation, because it’s autonomous,” he says. “But I can understand that some people need constant data connection to the autopilot, so they’d need a slightly larger link.”

The chip was designed with the help of a U.S.-based electronics company called 1Bitsquared, which will sell Lisa/S chips starting in January 2014. But since both the hardware and software is open source, Remes says any company will be able to sell chips based on the technology.

Source: http://www.wired.com

Quantum Paradox Seen in Diamond.

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A real-life version of Zeno’s ancient Greek conundrum could advance quantum computing

A quantum effect named after an ancient Greek puzzle has been observed in diamond, paving the way for the use of diamond crystals in quantum computer chips.

The quantum Zeno effect gets its name from the Greek philosopher Zeno of Elea, who lived in the fifth century bc and suggested that if the position of a flying arrow is well-defined for a moment of time, then it makes no progress in that moment, and so can never reach its destination.

In the quantum version of the arrow paradox, theoretical physicists posited in 1977 that if a quantum system is measured often enough, its state will be unable to progress, as if it were true that ‘a watched pot never boils’. The hypothesis arises from a fundamental postulate of quantum theory, which says that measuring a property of an object, such as its position, affects its state. The quantum Zeno effect was first observedexperimentally in 1989 in laser-cooled ions trapped by magnetic and electric fields.

Now, quantum physicist Oliver Benson and his colleagues at Humboldt University in Berlin have seen the effect in a diamond crystal — a material that would be easier to manufacture on a large scale for quantum computing. The team posted its paper on the arXiv and it has been accepted for publication in Physical Review A.

Disrupted oscillations
The researchers focused on nitrogen–vacancy (NV) centers, imperfections in diamond that arise where an atom of nitrogen and an empty space replace carbon atoms at two neighboring spots in the crystal lattice. The team used microwaves to change the magnetic spin state of an electron located at an NV center, and then used a laser beam to trigger red fluorescence that revealed which of two possible states the electron was in at any given moment. When they measured the NV center in this way, the researchers found that the oscillation between the two states was disrupted — just as would be expected if the quantum Zeno effect were operating.

“The first step is to see the effect is there, but the next step is to implement quantum gates based on diamond,” says Benson, referring to the quantum analogue of the logic gates that form the integrated circuits in ordinary computer chips. In quantum computing, information is stored in the quantum states of carriers such as photons or diamond defects. But so far, decoherence, a degradation of the delicate states caused by noise in the environment, has prevented researchers from storing more than a few bits of linked quantum information in a diamond crystal at a time. Constantly measuring the states could protect them from uncontrolled decay and allow researchers to scale up the amount of information stored, says Benson.

Ronald Walsworth, an atomic physicist at Harvard University in Cambridge, Massachusetts, whose team made a tentative suggestion in 2010 that the quantum Zeno effect operates in diamond, says that evidence is growing, but that it will probably need to be clearer that the disruption of oscillations is due to the quantum process, and not other effects, before it can be used for quantum computing.

Quantum physicist Ronald Hanson, who works with nitrogen vacancies at Delft University of Technology in the Netherlands, says that Benson’s experiment, together with an April paper showing that spins in NV centers located 3 meters apart can be linked, indicates that diamond is gaining ground as a convenient material for quantum computing. “In a few years, we will be overtaking the ion traps,” he says.

Source: http://www.scientificamerican.com

Solar Hydrogen Production Breakthrough.

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Using a simple solar cell and a photo anode made of a metal oxide, HZB and TU Delft scientists have successfully stored nearly five percent of solar energy chemically in the form of hydrogen. This is a major feat as the design of the solar cell is much simpler than that of the high-efficiency triple-junction cells based on amorphous silicon or expensive III-V semiconductors that are traditionally used for this purpose. The photo anode, which is made from the metal oxide bismuthvanadate (BiVO4) to which a small amount of tungsten atoms was added, was sprayed onto a piece of conducting glass and coated with an inexpensive cobalt phosphate catalyst.

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Basically, we combined the best of both worlds,” explains Prof. Dr. Roel van de Krol, head of the HZB Institute for Solar Fuels: “We start with a chemically stable, low cost metal oxide, add a really good but simple silicon-based thin film solar cell, and — voilà — we’ve just created a cost-effective, highly stable, and highly efficient solar fuel device.”

Thus the experts were able to develop a rather elegant and simple system for using sunlight to split water into hydrogen and oxygen. This process, called artificial photosynthesis, allows solar energy to be stored in the form of hydrogen. The hydrogen can then be used as a fuel either directly or in the form of methane, or it can generate electricity in a fuel cell. One rough estimate shows the potential inherent in this technology: At a solar performance in Germany of roughly 600 Watts per square meter, 100 square meters of this type of system is theoretically capable of storing 3 kilowatt hours of energy in the form of hydrogen in just one single hour of sunshine. This energy could then be available at night or on cloudy days.

Metal oxide as photo anode prevents corrosion of the solar cell

Van de Krol and his team essentially started with a relatively simple silicon-based thin film cell to which a metal oxide layer was added. This layer is the only part of the cell that is in contact with the water, and acts as a photo anode for oxygen formation. At the same time, it helps to prevent corrosion of the sensitive silicon cell. The researchers systematically examined and optimized processes such as light absorption, separation of charges, and splitting of water molecules. Theoretically, a solar-to-chemical efficiency of up to nine percent is possible when you use a photo anode made from bismuth vanadate, says van de Krol. Already, they were able to solve one problem: Using an inexpensive cobalt phosphate catalyst, they managed to substantially accelerate the process of oxygen formation at the photo anode.

A new record: More than 80 percent of the incident photons contribute to the current!

The biggest challenge, however, was the efficient separation of electrical charges within the bismuth vanadate film. Metal oxides may be stable and cheap, but the charge carriers have a tendency to quickly recombine. This means they are no longer available for the water splitting reaction. Now, Van de Krol and his team have figured out that it helps to add wolfram atoms to the bismuth vanadate film. “What’s important is that we distribute these wolfram atoms in a very specific way so that they can set up an internal electric field, which helps to prevent recombination,” explains van de Krol. For this to work, the scientists took a bismuth vanadium wolfram solution and sprayed it onto a heated glass substrate. This caused the solution to evaporate. By repeatedly spraying different wolfram concentrations onto the glass, a highly efficient photo-active metal oxide film some 300 nanometers thick was created. “We don’t really understand quite yet why bismuth vanadate works so much better than other metal oxides. We found that more than 80 percent of the incident photons contribute to the current, an unexpectedly high value that sets a new record for metal oxides” says van de Krol. The next challenge is scaling these kinds of systems to several square meters so they can yield relevant amounts of hydrogen.

Source: http://www.sciencedaily.com