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December 21, 2009

Technology Roundup - Quantum computer Algorithm

1. MIT Technology Review: Seth Lloyd describes the utility of the new quantum computing algorithm for linear equations.

MIT researchers, however, have developed a new algorithm that could solve systems of linear equations with exponential speed--improving video processing, weather modeling, and population analysis, among other applications. For even the easiest trillion-­variable problems, "a supercomputer's going to take trillions of steps," says mechanical-­engineering professor Seth Lloyd, who developed the new algorithm along with postdoc Avinatan ­Hassidim and Aram Harrow '01, PhD '05. "This algorithm will take a few hundred."

The trillion solutions to a trillion-variable problem would thus be stored on only about 40 qubits. But extracting all trillion solutions from the qubits would take a trillion steps, eating up all the time that the quantum algorithm saved.

Still, researchers can derive potentially useful information by performing quick measurements on the qubits. "You can figure out, for instance, [the trillion solutions'] average value," Lloyd says. Such measurements could answer questions like "In this very complicated ecosystem with, like, 10 to the 12th different species, one of which is humans, in the steady state for this particular model, do humans exist?" says Lloyd. "That's the kind of question where a classical algorithm can't even provide anything."


2. Boston College researchers have observed the “hot electron” effect in a solar cell for the first time and successfully harvested the elusive charges using ultra-thin solar cells, opening a potential avenue to improved solar power efficiency.

Theoretically, solar cells that can absorb hot and cool electrons could nearly double their power efficiency. Conventional solar cells can convert at most about 35% of sunlight energy into electricity, and the rest is wasted as heat. By absorbing the hot electrons, solar cells could achieve efficiencies of up to 67%. (MIT Technology Review)

The ultra-thin cells demonstrated overall power conversion efficiency of approximately 3 percent using absorbers one fiftieth as thick as conventional cells. The team attributed the gains to the capture of hot electrons and an accompanying reduction in voltage-sapping heat. The researchers acknowledged the film’s efficiency is limited by the negligible light collection of ultra-thin junctions. However, combining the film with better light-trapping technology – such as nanowire structures – could significantly increase efficiency in an ultrathin hot electron solar cell technology.

The problem is that because they're so thin, the solar cells let most of the incoming light pass through them. As a result, they convert only 3 percent of the energy in incoming light into electricity. "I think it's promising," Beard says. But he adds that so far they're only showing "a pretty small effect."

Naughton says that his team plans to address this problem using nanowires. The basic idea, put forward by many different researchers now, is to make forests of nanowires that will absorb light along their lengths. And because each nanowire is thin, the electrons won't have far to travel to escape to a conductive layer on its surface. This could make it possible to replicate the hot electron effect seen in the thin solar cells. Naughton and colleagues are commercializing such nanowires via a startup called Solasta, based in Newton, MA, which is being funded by the respected venture capital firm Kleiner Perkins Caufield & Byers.

The researchers also hope to increase the number of hot electrons they collect from the absorbed light. To do this, they are turning to an approach taken by Martin Green, a professor at the University of New South Wales in Australia and a leader in using hot electrons in solar cells. This method involves incorporating a layer of quantum dots, which act as a sort-of filter, selectively extracting higher-than-normal-voltage electrons, Beard says. Naughton says that Solasta has already demonstrated that it's possible to incorporate such quantum dots into the company's nanowires.




3. Broadcom has a new mobile phone processor the BCM2763. The BCM2763 VideoCore IV Processor Features 1080p Video, 20 Megapixel Photos and 1 Gigapixel Graphics in an Ultra-Low Power 40 Nanometer Design. So your mobile phone would have 20 megapixel camera, HD video camcorder and a High def display. Handsets utilizing this new 40nm VideoCore IV multimedia processor technology are expected to reach the market in 2011.

The BCM2763 multimedia processor features the most advanced mobile high definition (HD) camcorder and video playback, up to 20 megapixel digital camera and photo image processing, and 1 gigapixel 2D/3D graphics rendering for a world-class gaming experience. HD video, 3D games and high resolution 20 megapixel pictures can be displayed at top quality on full-sized HD televisions and monitors using an on-chip industry standard HDMI interface. Additionally, the BCM2763's highly integrated architecture reduces bill-of-materials (BOM) cost to help drive sophisticated multimedia features into more affordable handsets


The last sentence means that they expect the BCM2763 phones to be reasonably priced.

4. Crowlspace determines that if Digital quantum batteries can increase the energy density and have fast energy discharge that they will enable Friedwardt Winterberg’s fusion pulse designs.

A mere 10 MJ is enough for the D-T triggered D-D pulse units to implode, but it has to be pumped into the target in a nanosecond – a power of 10 quadrillion watts (10 petawatts, 10^16 W.) In his original papers Winterberg outlines two multi-use triggering systems – a super-Marx Generator, which is a huge linear bank of Marx generators, and a gigavolt charge build up on a space-ship in the high vacuum of space.

But what if there’s a different way? A new capacitor design theoretically has more than enough power (~10^19 W/kg estimated) and enough energy storage (1 MJ/kg) to allow a very light weight triggering system for fusion


Nextbigfuture has about 20 articles on Winterberg's ideas for nuclear fusion commercial energy and nuclear fusion spaceships.

Winterberg Summary


Adam Crowl, crowlspace, points out that with the 6.3% of light speed exhaust velocity from Winterbergs deuterium fusion rocket design means a 120,000 ton starship attached to 12,000,000 tons of deuterium can do a delta-vee of ~0.2 c (20% of lightspeed). This would be using the two stage configuration of the Project Daedelus (which was also based on Winterberg ideas). Daedelus had exhaust velocity of 3% of light speed.

With an efficient magnetic sail that means the journey speed approaches ~0.2 c, albeit with the mass-penalty of the sail. Perhaps a plasma-magnet can be formed at such speeds, with a quite different decceleration profile to the mag-sail, since the artificial magnetosphere balloons to match the plasma ram-pressure. Essentially the size goes up as the relative speed goes down, thus allowing a more-or-less constant braking force. A decceleration of 0.1 m/s2 will bring the vehicle to a halt in ~19 years over about 1.9 light-years from 0.2 c.


From Winterberg's paper: Neutron entrapment in an autocatalytic thermonuclear detonation wave is a means to increase the specific impulse and to solve the large radiator problem. The maximum exhaust velocity becomes 6.3% of light speed.

Project Daedelus

Daedalus would be constructed in Earth orbit and have an initial mass of 54,000 metric tons, including 50,000 tons of fuel and 500 tons of scientific payload. Daedalus was to be a two-stage spacecraft. The first stage would operate for two years, taking the spacecraft to 7.1% of light speed (0.071 c), and then after it was jettisoned the second stage would fire for 1.8 years, bringing the spacecraft up to about 12% of light speed (0.12 c) before being shut down for a 46-year cruise period. Due to the extreme temperature range of operation required (from near absolute zero to 1,900 K) the engine bells and support structure would be made of beryllium, which retains strength even at cryogenic temperatures. A major stimulus for the project was Friedwardt Winterberg's fusion drive concept for which he received the Hermann Oberth gold medal award.

This velocity is well beyond the capabilities of chemical rockets, or even the type of nuclear pulse propulsion studied during Project Orion. Instead, Daedalus would be propelled by a fusion rocket using pellets of deuterium/helium-3 mix that would be ignited in the reaction chamber by inertial confinement using electron beams. 250 pellets would be detonated per second, and the resulting plasma would be directed by a magnetic nozzle. Due to the scarcity of helium-3 it was to be mined from the atmosphere of Jupiter via large hot-air balloon supported robotic factories over a 20 year period.

The second stage would have two 5-meter optical telescopes and two 20-meter radio telescopes. About 25 years after launch these telescopes would begin examining the area around Barnard's Star to learn more about any accompanying planets. This information would be sent back to Earth, using the 40-meter diameter second stage engine bell as a communications dish, and targets of interest would be selected. Since the spacecraft would not decelerate upon reaching Barnard's Star, Daedalus would carry 18 autonomous sub-probes that would be launched between 7.2 and 1.8 years before the main craft entered the target system. These sub-probes would be propelled by nuclear-powered ion drives and carry cameras, spectrometers, and other sensory equipment. They would fly past their targets, still travelling at 12% of the speed of light, and transmit their findings back to the Daedalus second stage mothership.


Marx Generators exist and Winterberg proposes putting one hundred of them in series to power a gigavolt fusion power system. Winterberg came up with the theory for the Z-pinch system that is being tested at the research labs now.

Winterbergs deuterium rocket uses similar principles to get to fusion as his most recent proposal for a fusion power system.

Winterberg's conjectured metastable explosive from using high pressures (100 million atmospheres) to alter molecules appears to have experimental confirmation from Young Bae of the Bae Institute

Winterbergs micro fusion work has been covered extensively on this site.

All of the articles that have been tagged with Winterberg

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