Motivation

Inside every molecule ticks an intricate quantum-mechanical clockwork, emerging from the interplay of its constituent elementary particles and their fundamental interactions.This complex system of discrete energy states and the transitions between them reflects the strength and character of the electromagnetic, strong and weak forces, and is uniquely dependent on the values of the constants of nature. As a result, a very accurate measurement of the 'beats of this clock' has the power to confirm or reject the predictions of the Standard Model (SM) of particle physics.

The possibility of finding a difference between the measurement and the predictions of the Standard Model is tantalizing: it would signify the existence of physics beyond the Standard Model, and it would open a gateway to address some of the most important open questions about the foundations of our world:

Where is the anti-matter?

What is dark matter?

In our work selected diatomic molecules will be brought in a state that acts as a very sensitive antenna to signals from physics beyond the Standard Model. The key to this sensitivity is the occurrence of close-lying rotational states with a different dependence on physical constants and symmetries. However, so far this sensitivity could not be exploited; the main obstacle to reach a sufficiently high precision in molecular spectroscopy is the limited control over the molecules and their internal states. We have therefore started an experimental program to bring clouds of molecules to a complete standstill, prepare and trap them in a single quantum state and use lasers to cool them to a temperature of ~200 microKelvin. The key techniques that we use are explained in the section on cooling and controlling neutral molecules.