[LINK] entangled light

[stephen at melbpc.org.au]

Toshiba invention brings quantum computing closer

Ben Hirschler LONDON Wed Jun 2, 2010 1:02pm LONDON 
<www.reuters.com/article/idUSTRE6514VJ20100602?
feedType=nl&feedName=ustechnology> (snip)


(Reuters) - Superfast quantum computing, one of the holy grails of 
science, could be a step closer following the invention of a new device 
capable of producing so-called "entangled" light on demand.

Scientists at Toshiba Corp's research center in Cambridge, England, said 
on Wednesday their Entangled Light Emitting Diode (ELED) opened a path to 
ultra-powerful semiconductor chips.

Andrew Shields of Toshiba and colleagues believe they have a key tool in 
the form of a simple-to-make device, which can be hooked up to a battery 
to produce entangled light, as and when required.

"It's a big step because it means you can now start to integrate lots of 
devices on a single chip," Shields said.

Quantum computers based on optical processes need a large number of 
entangled photons, where light particles are linked so that they exist in 
two possible states simultaneously -- something Albert Einstein described 
as "spooky."

Until now, making entangled light has only been possible using bulky 
lasers. But Toshiba's new ELED uses standard semiconductor technology and 
is made of gallium arsenide, a common material in optical electronics.

It is similar to conventional light emitting diodes used in consumer 
electronics and modern household lighting, except it contains a tiny 
region, called a quantum dot, which converts electrical current into 
entangled light.

The Toshiba team, working with the University of Cambridge's Cavendish 
Laboratory, described their invention in a paper in the journal Nature.

Other researchers are using atoms or electrons, rather than photons, as 
quantum computing building blocks. But Shields said the ELED marked a big 
step forward for the optical approach.

Quantum computers are likely to be used initially to solve problems that 
are otherwise virtually intractable, such as modeling new molecules in 
pharmaceuticals.

Further off, they might also offer an answer when technology based on 
conventional silicon chips bumps up against the laws of physics and 
components cannot be made any smaller.  (Editing by David Holmes)

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Cheers,
Stephen