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NMR Quantum Computing
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A nearly ideal physical system that can be used as quantum computer is
a single molecule, in which nuclear spins of individual atoms
represent qubits . Using nuclear
magnetic resonance (NMR) techniques, invented in the 1940's and widely
used in chemistry and medicine today, these spins can be manipulated,
initialized and measured. Most NMR applications treat spins as little
"bar magnets", whereas in reality, the naturally well-isolated
nuclei are non-classical objects. The quantum behavior of the spins can be
exploited to perform quantum computation; for example, the carbon and
hydrogen nuclei in a chloroform molecule (as shown below) represent
two qubits. Applying a radio-frequency pulse to the hydrogen nucleus
addresses that qubit, and causes it to rotate from a |0> state to a
superposition state. Interactions through chemical bonds allow
multiple-qubit logic to be performed. In this manner, applying
newly developed techniques to allow bulk samples with many molecules
to be used, small-scale quantum algorithms have been experimentally
demonstrated with molecules such as Alanine, an amino acid. This
includes the quantum search algorithm, and a predecessor to the
quantum factoring algorithm.
Further Information
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