NQontrol: An open-source platform for digital control-loops in quantum-optical experiments.

In this paper, we present NQontrol, a digital feedback-control solution based on the ADwin platform that delivers eight simultaneous feedback loops running with 200 kHz sampling frequency and offers five second-order filtering sections per channel for flexible shaping of the feedback loop. With this system, we demonstrate a Pound-Drever-Hall lock of an optical resonator and compare its performance to an analog reference implementation. A comprehensive support package written in Python, together with a web-based graphical user interface, makes the system quick to setup and easy to use, while maintaining the full flexibility of open-source platforms.