Issue no. 36, 2007
Published: Nov 09, 2007 |
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 'Light trap' is a step towards quantum memory |
| Researchers automate silicon chip debugging |
| Tiny rods steer themselves |
| Make oceans vast carbon sinks, US researchers say |
| Peanut shells filter copper, Turkish researchers report |
| Hydrogen power lights up the seas |
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| 'Light trap' is a step towards quantum memory |
The best place to hold quantum information might be within a small, cold
cloud of gas. Two teams from Kastler Brossel Laboratory in Paris, France
and the Institute for Quantum Electronics Zurich, Switzerland, have
independently succeeded in placing a cloud of chilled rubidium atoms
within an optical cavity, which traps light between two opposed mirrors.
The combination could one day form a quantum memory element.
Quantum information deals in qubits, which can be a blend of 0 and 1,
yes and no. In theory, you can store a qubit by using a photon to change
the energy levels of an atom. The photon's mixed yes-and-no quantum
state is written onto the atom, which ends up in the same mixture of
high- and low-energy states. Reading this type of memory can be
treacherous, however. The atom could simply drift away, or it could
re-emit a photon containing the qubit in a random direction.
These problems might be solved by using not one atom but a collection of
them, in a state called a Bose-Einstein condensate (BEC). All the atoms
in a BEC share the same quantum state. The researchers have put a BEC
between two mirrors, which form an optical cavity trapping photons of a
particular wavelength. The BEC can be forced to respond to exactly that
wavelength, so that it should only emit photons in a controlled
direction within the cavity. A BEC can more easily be cooled to very low
temperatures than a single atom. The cold BEC has no thermal motion and
does not drift away, meaning the information held in it could be stored
for longer. |
| New Scientist / Nature
Nov 07, 2007 |
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| Researchers automate silicon chip debugging |
Researchers from the University of Michigan have developed a technology
that automates the process of debugging silicon chip designs.
Fixing design bugs and dodgy wiring connections is a lengthy
trial-and-error process that often costs millions of dollars. In the
current system, a chip design is first validated in simulations. Then a
draft is cast in silicon, and this first prototype undergoes additional
verification with more realistic applications. If a bug is detected at
this stage, an engineer must narrow down the cause of the problem and
then craft a fix that does not disrupt the delicate balance of all other
components of the system. This can take several days. Engineers then
produce new prototypes incorporating all the fixes. This process repeats
until they arrive at a prototype that is free of bugs.
However, the university's 'FogClear' method uses puzzle-solving search
algorithms to diagnose problems early on and automatically adjust the
blueprint for the chip. It reduces parts of the process from days to
hours. Its creators say that the computer-aided design tool can catch
subtle errors that several months of simulations would still miss. |
| VNUnet UK
Nov 07, 2007 |
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| Tiny rods steer themselves |
Many tiny organisms propel themselves towards food or away from toxins
in a process called chemotaxis. Now researchers from Pennsylvania State
University have created tiny metal rods that are the first
non-biological entities to show this behaviour by 'swimming' towards
regions in a solution with a higher concentration of a certain chemical.
Chemotaxis is the tendency of some biological organisms to move in
response to a gradient in chemical concentration. In non-biological
systems, chemotaxis could be useful for directing the motion of small
particles in fluids or assembling collections of particles into
nanostructures – without the need for applying external electric or
magnetic fields. However, the process is extremely complex and this has
made it very difficult to mimic the effect in non-biological systems.
The team made a large number of tiny metal rods. Each rod was gold along
one half of its length and platinum along the other. The rods were
placed in a dish containing pure water and a piece of gel that contained
hydrogen peroxide, which slowly leached from the gel into the water,
creating a concentration gradient in the surrounding water. After 110
hours more than 70% of the rods had accumulated next to the gel because
hydrogen peroxide undergoes different chemical reactions at the gold and
platinum ends of the rods. This drives fluid along the rod causing it to
move. The particles' speed increases with the local concentration of
hydrogen peroxide and so on average the rods are 'attracted' to the gel. |
| PhysicsWorld / Phys. Rev. Lett.
Nov 06, 2007 |
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| Make oceans vast carbon sinks, US researchers say |
Speeding up a natural process through 'electrochemical weathering' could
be used to absorb carbon in oceans and reduce the impact of climate
change, according to researchers from Harvard and Pennsylvania State
University.
Oceans have absorbed about one-third of the carbon dioxide that humans
have produced, but the process is very slow. And the more acidic oceans
are, the less CO2 they can absorb. The researchers said they found a way
to remove hydrochloric acid from the ocean and neutralise it using
silicate from volcanic rocks. That increases the ocean's alkalinity, so
it can store more atmospheric CO2 as bicarbonate, already the most
common form of carbon in the oceans.
In nature, CO2 is dissolved by fresh water, forming a weak acid. The
acid is neutralised as water filters through rocks, producing an
alkaline solution of carbonate salts. Eventually the water reaches an
ocean, where the alkaline solution holds the dissolved carbon until it
eventually becomes a sediment. |
| CBC News / Environmental Science and Technology
Nov 08, 2007 |
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| Peanut shells filter copper, Turkish researchers report |
The lowly peanut shell has potential to remove potentially dangerous
copper from water, say Turkish researchers from Mersin University. The
research may have significant implications for both the agricultural
industry and the environment, because peanut shells are a huge waste
product, and copper pollution is common in areas where industrial
residues leach into the water supply.
The researchers tested peanut husks against pine sawdust to see which of
the waste products was better at removing copper ions from water. The
peanut husks removed 95 per cent of the copper ions, more than twice the
44 per cent rate for pine sawdust.
The team measured the level of copper ions that could be extracted from
water at different temperatures, acidity, flow rate, and initial
concentration of dissolved copper. The longer the wastewater is exposed
to the materials, the more efficient the process, they concluded. |
| CBC News / International Journal of Environment and Pollution
Nov 08, 2007 |
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| Hydrogen power lights up the seas |
The Soviet Union once powered lighthouses on its Arctic coast using
radioactive batteries, leaving its successors the problem of disposing
of the nuclear waste. Now a cleaner technology is being harnessed to
power lighthouses in remote places: fuel cells.
A consortium led by CPI of Wilton, Teesside, UK, is using a fuel cell to
power the South Gare lighthouse at Redcar on England's North Sea coast.
It was previously prone to power outages when the mains power cable was
damaged by the wind and heavy seas.
CPI has proofed its fuel cell against the ravages of salty air and
seawater, and has developed a novel water-based cooling system for it,
too. CPI said the light is working reliably - and like its predecessor
is visible from some 40 kilometres out at sea. |
| New Scientist
Nov 06, 2007 |
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