Improved phase factor determination in quantum signal processing

Quantum Signal Processing (QSP) provides a framework for implementing polynomial functions of non-unitary matrices on quantum computers. However, determining the set of parameters, known as phase factors, needed to implement a particular polynomial can be challenging from a classical pre-processing perspective. The recently-proposed Generalized Quantum Signal Processing (GQSP) framework provides an efficient algorithm for finding these parameters (at the level of GQSP). Based on a correspondence between QSP and GQSP, we discuss improvements to the determination of QSP phase factors.