Feedback-based quantum algorithms

This talk will present feedback-based quantum algorithms (FQAs) as an optimization-free paradigm that is applicable to solving a broad range of problems on quantum computers. Within this paradigm, feedback from qubit measurements is used to build up quantum circuits in a layer-wise manner, such that the quality of the solution to a problem under consideration improves monotonically with each added layer. I will begin this talk by overviewing the theoretical foundations of FQAs, which are rooted in quantum Lyapunov control theory. I will then outline the general steps for formulating and implementing FQAs, highlight the tradeoffs associated with different FQA design choices, and discuss new developments in FQAs from the last year. Throughout this talk, context will be provided using examples of FQAs for quantum simulation, optimization, and machine learning applications. Sandia National Labs is managed and operated by NTESS under DOE NNSA contract DENA0003525. SAND2022-14644 A.