[Paleopsych] The impact of its environment on a quantum computer

Steve Hovland shovland at mindspring.com
Fri Apr 15 13:29:53 UTC 2005

Scientists have discovered how the performance of a quantum computer can be 
affected by its surrounding environment. The study, published in the latest 
issue of the journal Science, will help engineers to better understand how 
to integrate quantum components into a standard office computer - moving us 
one step closer to a future of quantum computing.
The collaborative team from the London Centre for Nanotechnology, 
University College London (UCL), the Paul Scherrer Institute/ETH in 
Switzerland and the Universities of Chicago and Copenhagen, have shown how 
its environment can radically alter the behaviour of a quantum computer, an 
effect which is not present for conventional computers of the type that 
exist now on our desktops.
Professor Gabriel Aeppli of UCL's Dept of Physics and the Director of the 
London Centre for Nanotechnology says: "One of the most important questions 
in natural sciences is whether quantum mechanics is relevant to everyday 
experience. The famous puzzle of whether Schroedinger's cat is dead or 
alive is the most graphic representation of this question, traditionally 
considered an academic point of no real practical import.
"However, the recent demand for secure communications and ultra-high speed 
computation has made the answer highly relevant to future technology where 
quantum 'qubits' replace the classical binary bits 0 and 1 on which current 
digital electronics and communications rely.
"To engineer quantum computers it is necessary for the qubits to be stable 
in realistic settings, such as the integrated circuit packages in a typical 
office computer. Physicists refer to such settings as the 'environment', or 
more picturesquely, the 'bath', and the challenge is to control and 
minimize the interactions of the qubits with the bath.
"Quantum engineering will require careful attention to the 'baths' in which 
the new devices will be immersed, in the same way that we worry about 
turbulent air conditions when we design aircraft." Baths by their very 
nature can be difficult to define and therefore the systematic study of 
interactions between qubits and baths is in its infancy. The new work shows 
how a well-specified bath affects the qubits in a crystal which behaves as 
a very primitive quantum computer. For example, the bath will change how 
the qubits will move in response to stimuli such as radio waves. The work 
also suggests that the effect can be controlled by radio waves themselves 
and by the temperature of the bath.

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