Applications
of Nuclear Magnetic Resonance in Quantum Computing
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 [1].
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
