Fast Parametric ISAR Autofocussing Using Quantum Search

Parametric autofocussing in inverse synthetic aperture radar compensates for phase shifts in return echoes caused by target motion which is unpredictable a priori. On top of enabling effective azimuth focussing, it facilitates the estimation of the target motion parameters. Traditionally, the parametric autofocussing problem is tackled with a combination of heuristic methods and exhaustive local search. The latter component constitutes an unstructured database search, which is exactly the type of problem for which quantum search is advantageous. This work describes the problem in the light of quantum search and then lays out a theoretical implementation. After this, a complexity analysis is performed which concludes that, while far beyond the reach of current quantum hardware, an asymptotic improvement in time can be achieved.