Research Fellows Directory
Dr Benedict Murdin
University of Surrey
Professor Ben Murdin's research is on quantum computing with atoms encased inside a silicon chip. This work is closely related to the latest Nobel prize for physics – the laureates Haroche and Wineland pioneered quantum computing in atoms and ions suspended in empty vacuum. They developed techniques for putting each atom into a state of oscillating at two different frequencies at once, like a chord on a guitar string.
Erwin Schrodinger, one of the fathers of quantum physics speculated that this weird behaviour might eventually enable construction of a machine that could one day be capable of making a large every-day object do two jobs at once. Schrodinger’s thought-experiment involved making a cat be simultaneously alive and dead, but most researchers are instead trying to harness this ability to make more powerful computers. The problem is that the effect of surroundings is to disturb the delicate dual existence and cause the object to choose one state or the other, which is why successful experiments tend to be on very small objects in empty space. Using very similar optical techniques to Haroche and Wineland, we succeeded in putting phosphorus atoms into chord-like states that are simultaneously oscillating and not oscillating at the same time. The shocking thing for us was that the surrounding silicon did not disturb the delicate chord-like state of the phosphorus atoms much. The phosphorus atom is almost as big as a transistor in an ordinary silicon computer chip, so it is in contact with about a million other electrons from the silicon. When we started we thought that this would mean the weird wave-like motion of the phosphorus would instantly collapse giving us back the ordinary one-place-at-a-time particle motion. It turns out that there is plenty of time to do a computer operation, and we are now working on trying to replicate this with a single phosphorus atom rather than a big bunch of them, how to entangle adjacent atoms.
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