Friday, May 30, 2014

Bogus quantum teleportation claims

John Markoff reports in the NY Times:
Scientists in the Netherlands have moved a step closer to overriding one of Albert Einstein’s most famous objections to the implications of quantum mechanics, which he described as “spooky action at a distance.”

In a paper published on Thursday in the journal Science, physicists at the Kavli Institute of Nanoscience at the Delft University of Technology reported that they were able to reliably teleport information between two quantum bits separated by three meters, or about 10 feet.
This just means that an electron state was copied 10 feet away.
Classical bits, the basic units of information in computing, can have only one of two values — either 0 or 1. But quantum bits, or qubits, can simultaneously describe many values. They hold out both the possibility of a new generation of faster computing systems and the ability to create completely secure communication networks.

Moreover, the scientists are now closer to definitively proving Einstein wrong in his early disbelief in the notion of entanglement, in which particles separated by light-years can still appear to remain connected, with the state of one particle instantaneously affecting the state of another. ...

Succeeding at greater distances will offer an affirmative solution to a thought experiment known as Bell’s theorem, proposed in 1964 by the Irish physicist John Stewart Bell as a method for determining whether particles connected via quantum entanglement communicate information faster than the speed of light.

“There is a big race going on between five or six groups to prove Einstein wrong,” said Ronald Hanson, a physicist who leads the group at Delft. “There is one very big fish.” ...

To date, practical quantum computers, which could solve certain classes of problems far more quickly than even the most powerful computers now in use, remain a distant goal. A functional quantum computer would need to entangle a large number of qubits and maintain that entangled state for relatively long periods, something that has so far not been achieved.

A distributed quantum network might also offer new forms of privacy, Dr. Hanson suggested. Such a network would make it possible for a remote user to perform a quantum calculation on a server, while at the same time making it impossible for the operator of the server to determine the nature of the calculation.
This is craziness. Proving Einstein wrong is not a big deal, as all of the textbooks have said that he was wrong about quantum mechanics for 80 years.

Bell's theorem has been affirmed many times.

No faster computing or secure communication is going to come out of this work. This is just replicating an electron state. That's all.

Update: Lubos Motl has a rant about Brian Greene and other physicists and philosophers spreading confusion about quantum mechanics, and comments on the above experiment.

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