Quantum state engineering through PID control

The QPIDControl project will theoretically investigate the use of control schemes known from classical theory, namely proportional-integral-derivative (PID) controllers, to control the state of quantum systems.

Over the last decade, interest in applying measurement-based feedback control to quantum systems has increased considerably.

Given the versatility of PIDs, it is reasonable to expect that they may be applied to quantum systems, for instance for information processing and feedback control.Most experimental implementations of feedback loops in quantum systems exclusively rely on the proportional action.

Despite their relevance in classical control schemes, the integral and derivative actions have not been studied sufficiently in the context of quantum systems.

The goal of QPIDControl is to achieve a new level of understanding of feedback loops by studying the combined effect of the proportional, integral and derivative actions, and to demonstrate the applicability PIDs for the generation of quantum states.

First, we will theoretically study the use of PIDs for cooling and controlling a mechanical degree of freedom in an optomechanical system. Second, we will study how classical control schemes translate into quantum systems.

Third, we will apply PIDs to characterise the generation and stabilisation of the state of an atom coupled to a waveguide.During the project, we will actively collaborate with experimental groups to put the results into practice.

The results of the project will be useful, for instance, for enhancing the design of optomechanical gravitational wave detectors, and in quantum computing, where qubits need to be initialised in specific states.