Susskind lecture on Quantum Entanglements

Quantum Entanglement for Detection

Science Daily reports that engineer Seth Lloyd has proposed using quantum mechanically entangled photons to develop detection systems that would be a million times more efficient than anything currently in existence. The quantum based photodection system would have widespread applications, from more efficient night-vision equipment to CT scanners that used lower levels of radiation.

For the more technically inclined, here is a paper by Lloyd and his colleagues on enhanced imaging utilizing quantum theory:

http://xxx.lanl.gov/abs/0804.2875

Just to note, this area of research was pioneered by Jonathan K. Dowling and others, who are not mentioned in the Science Daily article:

http://xxx.lanl.gov/abs/0805.0296

As an aside, here is a video of Seth Lloyd, talking about quantum computers, and interestingly their capacity (if one could be built) to surpass the capacity of a human brain. I am really interested in this point because I don't believe classical computers or current artificial intelligence (AI) can do this, no matter how advanced they become.

Something Lloyd says is "You don't have to understand the nature of things to build cool devices". OK, spoken like a true Geek. "Cool" devices are one thing, but personally, I am more interested in how the universe works and why it works the way it does rather than some engineering marvel. I want to understand the nature of reality like David Deutsch does.

Quantum Entanglement

In 1935 Einstein wrote what might be considered his parting shot against quantum theory, his paper with Podolsky and Rosen describing entanglement. Einstein thought it highlighted the fact that quantum theory was incomplete or wrong, calling it "spooky action at a distance". Now more than 70 years later physicists are sure entanglement is a real phenomenon, its routinely produced in the laboratory and even being used in some futuristic practical applications like quantum computing.

But its not the practical applications that really interest me. What intrigues me is the notion that two physical entities in the universe can be connected across vast distances of space. I don't care what the quantum computer geeks say, so what if you can't transmit digital information instantaneously with entanglement? What really matters here in my opinion is the connection. The fact particles are connected in this way shows that the universe is a bit more mysterious-maybe way more mysterious-than we ever imagined.

In a recent article about this topic, which mentions (but did not describe in much detail) an experiment where scientists in Switzerland were looking to see if some signal traveled faster than the speed of light, a physicist named Nicolas Gisin remarks that nature seems able to "manifest events in multiple locations". Gisin goes on to assure us no signal can travel faster than the speed of light. Some have imagined that perhaps a faster-than-light signal connects two entangled particles.

I know there is a lot of evidence in support of special relativity-no reputable scientist disputes it and I'm not going to either. But let's not make it a religion. I think physicists are all too eager to dismiss the notion of a signal of some kind traveling faster than the speed of light. We don't want to be new age quacks but at the same time we need to keep an open mind. All too often in the history of science physicists just "knew" such and such was a fact and it turned out not to be. Maybe there are signals that can travel faster than the speed of light.

In any case, something is connecting the two entangled particles. Maybe they have some kind of link through higher dimensions.

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