Science > Physics > Measure the state of quantum bits in a quantum computer without disturbingthe state
| Topic: |
Science > Physics |
| User: |
"Sam Wormley" |
| Date: |
22 Nov 2005 10:48:49 AM |
| Object: |
Measure the state of quantum bits in a quantum computer without disturbingthe state |
Breakthrough for quantum measurement
http://physicsweb.org/articles/news/9/11/13/1
22 November 2005
Two teams of physicists have measured the capacitance of a Josephson
junction for the first time. The methods developed by the two teams
could be used to measure the state of quantum bits in a quantum
computer without disturbing the state.
A Josephson junction consists of two superconducting layers separated
by a thin insulating layer. Brian Josephson of Cambridge University won
the Nobel prize in 1973 for predicting, while he was still a PhD
student, that the Cooper pairs in the superconducting layers would be
able to tunnel through the insulating layer without losing their
superconducting properties. Josephson junctions are widely used in many
electronic devices, including logic circuits, memory cells and
amplifiers. Superconducting quantum interference devices (SQUIDs), also
rely on the junctions to measure extremely small magnetic fields.
In the classical regime, the junction behaves like an inductance. In
the 1980s, however, theorists predicted that a Josephson junction would
behave like a capacitor if it was small enough. Now, Per Delsing and
colleagues at Chalmers University of Technology in Sweden, and
independently, Pertti Hakonen and co-workers at Helsinki University of
Technology and the Landau Institute of Theoretical Physics in Moscow
have observed this effect in experiments for the first time.
See: http://physicsweb.org/articles/news/9/11/13/1
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| User: "Bob Cain" |
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| Title: Re: Measure the state of quantum bits in a quantum computer withoutdisturbing the state |
22 Nov 2005 08:50:15 PM |
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Sam Wormley wrote:
Breakthrough for quantum measurement
http://physicsweb.org/articles/news/9/11/13/1
22 November 2005
Two teams of physicists have measured the capacitance of a Josephson
junction for the first time. The methods developed by the two teams
could be used to measure the state of quantum bits in a quantum
computer without disturbing the state.
And cryptography is forced to pick up its bags and move on yet again.
Bob
--
"Things should be described as simply as possible, but no simpler."
A. Einstein
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| User: "Ben Rudiak-Gould" |
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| Title: Re: Measure the state of quantum bits in a quantum computer withoutdisturbing the state |
29 Nov 2005 01:46:59 PM |
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Bob Cain wrote:
Sam Wormley wrote:
Breakthrough for quantum measurement
http://physicsweb.org/articles/news/9/11/13/1
[...] The methods developed by the two teams
could be used to measure the state of quantum bits in a quantum
computer without disturbing the state.
And cryptography is forced to pick up its bags and move on yet again.
No, just misreporting as usual. I promise you they haven't circumvented the
uncertainty principle.
-- Ben
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