Deterministic Grover search with a restricted oracle
Tanay Roy, Liang Jiang, David Schuster · Physical Review Research · 2022
Grover's quantum search algorithm provides a quadratic quantum advantage over classical algorithms across a broad class of unstructured search problems.The original protocol is probabilistic, returning the desired result with significant probability on each query but, in general, requiring several iterations of the algorithm.We present a modified version to return the correct result with certainty without having user control over the quantum search oracle.Our deterministic, two-parameter "D2p" protocol utilizes generalized phase rotations replacing the phase inversions after a standard oracle query.The D2p protocol achieves a 100% success rate in no more than one additional iteration compared to the optimal number of steps as in the original Grover's search enabling the same quadratic speedup.We also provide a visualization using the Bloch sphere for enhanced geometric intuition.