Considerations of Closed-loop Control on Quantum Computers using a Modified Grover's Algorithm for Simulation of a Chemical Process*

Quantum computers are of increasing interest in engineering applications such as modeling, optimization, and machine learning. Another field is process control, which involves the use of automated computer systems to manage process operation, where the method by which quantum algorithms might be implemented is unclear. The use of quantum computations in control may introduce factors that need to be accounted for such as nondeterminism, noise, and rounding effects. Our initial research sought to understand the effects of rounding and nondeterminism when implementing control on quantum computers. This was addressed though the design of a quantum circuit, which utilized many sequential Grover’s algorithm gates to encode a lookup table representing a controller, and through a control-theoretic study using an advanced control framework called Lyapunov-based economic model predictive control. This work focuses on extending our work through the application of the algorithm and theory using a chemical process example. This includes multiple objectives, namely concerns raised from the creation of the lookup table, a method of modifying the quantum circuit to prevent selecting unwanted control inputs, and the use of auxiliary classical control to ensure system stability.