A quantum optimal control perspective on variational quantum algorithms

The availability of noisy quantum processors has sparked a flurry of research into the development of variational quantum algorithms (VQAs). However, progress is needed to improve the utility of VQAs in practice. In this talk, I will explore a variety of ways that the theory of quantum optimal control could be used to enable advances in VQA research. I will begin by identifying VQAs and quantum optimal control as formulations of variational optimization at the circuit level and pulse level, respectively. I will then discuss ways that these different levels of abstraction may be connected, in order to facilitate the application of quantum control theory to VQA challenges associated with ansatz selection, optimization landscapes, noise, and robustness. Examples of recent work at the intersection of quantum control and VQAs will be given, and the talk will conclude with a discussion of open questions and a look to the future.

This work was supported by DOE SC ASCR through the Quantum Computing Application Teams program. Sandia National Labs is a multimission laboratory managed and operated by NTESS, LLC, a wholly owned subsidiary of Honeywell International Inc., for DOE’s NNSA under contract DE-NA0003525.