'Quantum computer' a stage closer with silicon breakthrough

[n2doc]

The remarkable ability of an electron to exist in two places at once has been controlled in the most common electronic material - silicon - for the first time. The research findings - published in Nature by a UK-Dutch team from the University of Surrey, UCL (University College) London, Heriot-Watt University in Edinburgh, and the FOM Institute for Plasma Physics near Utrecht - marks a significant step towards the making of an affordable "quantum computer".


According to the research paper in Nature the scientists have created a simple version of Schrodinger's cat - which is paradoxically simultaneously both dead and alive - in the cheap and simple material out of which ordinary computer chips are made.

"This is a real breakthrough for modern electronics and has huge potential for the future," explained Professor Ben Murdin, Photonics Group Leader at the University of Surrey. "Lasers have had an ever increasing impact on technology, especially for the transmission of processed information between computers, and this development illustrates their potential power for processing information inside the computer itself. In our case we used a far-infrared, very short, high intensity pulse from the Dutch FELIX laser to put an electron orbiting within silicon into two states at once - a so-called quantum superposition state. We then demonstrated that the superposition state could be controlled so that the electrons emit a burst of light at a well-defined time after the superposition was created. The burst of light is called a photon echo; and its observation proved we have full control over the quantum state of the atoms."

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http://www.physorg.com/news196516338.html

The electron orbits a phosphorus atom embedded in the silicon lattice, shown in silver. The undisturbed electron density distribution, calculated from the quantum mechanical equations of motion is shown in yellow. A laser pulse can modify the electron’s state so that it has the density distribution shown in green. Our first laser pulse, arriving from the left, puts the electron into a superposition of both states, which we control with a second pulse, also from the left, to give a pulse which we detect, emerging to the right. The characteristics of this "echo" pulse tell us about the superposition we have made. Credit: UCL

[caraher]

1. Nice

But I think there's perhaps a bit too much hype here just because they did this in silicon. They also needed a free-electron laser, and I'm pretty sure we're not ever going to see an "affordable" device based on free-electron lasers!

This may be slightly dated information but gives some notion of what's involved:

FELIX cost approximately $8.5M to build and install in an existing building. However, it is important to distinguish the cost of the machine from that of the complete user facility. The latter entailed remodeling and partially equipping five user rooms and cost an additional $3.5M. The 1994 operating costs for FELIX are budgeted at $1.75M and are expected to provide for 2000 hours of beam time; this translates to about $900/hr.

Here's what FELIX looks like.

Looks like the full text of the Nature article is available for free.