Quantum Computing: Origins and Directions
published: Jan. 6, 2014, recorded: October 2006, views: 4363
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Fear not: David DiVincenzo doesn’t spend much time “deep in the guts of the mathematics” during his “grand history” of quantum computing. Rather, he pays homage to the handful of thinkers who provided the field with its critical concepts.
The three men DiVincenzo profiles are “outsiders largely, people who were not so well connected with the roaring mainstream of what we do in academia and industrial research… people who had dreams.” He credits the well-known physicist Richard Feynman with inventing the subject, by proposing that computers might be built of quantum mechanical elements obeying quantum mechanical laws. Feynman envisioned the bits of these computers behaving differently from the bits in ordinary computers, and he puzzled about the possibility of a reversible computer that could run without expending energy.
While Feynman raised interesting questions, it was a very unfamous scientist who took the field to its next step. Steven Wiesner, the son of former MIT President Jerome Wiesner, worked for many years as a postal clerk, but “was a deep thinker nonetheless,” says DiVincenzo. In 1970, he explored the implications of simple quantum mechanical laws for secrecy. He had the practical notion of making banknotes counterfeit-proof, by printing them with “microtraps” holding photons, in addition to normal serial numbers. Such photons could never be copied, since they’d occupy random states of polarization. DiVincenzo says Wiesner’s notion of conjugate bases served as the beginning of quantum information theory.
In the late 70s and early 80s, small clusters of people became drawn to Feynman’s and Wiesner’s ideas, and spun out such new concepts as superdense coding, and quantum teleportation. Then a “third player came from apparently nowhere:” David Deutsch had the insight to take the quantum mechanics of a bit seriously, says DiVincenzo. Deutsch suggested that the fundamental carrier of quantum information is a qubit, which can exist as 0 and 1 at the same time. He developed a new logic system, a set of rules for quantum computing, “which are potentially realizable…Real systems are noisy but if you could make them obey the pristine law of quantum mechanics, this would be a new physical system that could support computation.”
DiVincenzo sees a direct line from Deutsch’s insights to a set of algorithms that form the basis for the current field of quantum computing. While the story is still unfolding, he says he’s confident quantum information processing “will eventually change the world.”
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