  A continuous, analog version of the Grover algorithm is realized using NMR.
The system studied is 23Na in a liquid crystal medium. The presence of
quadrupolar coupling makes the spin I=3/2 nucleus a 2-qubit system. Applying a
specially designed pulse sequence, the time evolution of the spin density
operator is described in an interaction representation which has no external
time-dependent radio-frequency fields. This approach is used to implement one
instance of the continuous Grover search for the transform of a uniform state
to a target state, and the implementation provides a clear physical
interpretation of the algorithm. The experimental results are in good agreement
with the theory.
