Searching for dark matter with a global network of optical atomic clocks

Observations at astronomical scales provide a strong evidence for existence of dark matter. The nature of dark matter composition, however, is still not known. Lack of detections of dark matter particles triggered multiple alternative theories. In this seminar, I will focus on dark matter candidates in form of scalar fields that couple to the Standard Model fields and yield variations of fundamental constants. In particular, variations of the fine-structure constant can be interpreted as a manifestation of dark matter fields. My presentation will be based on (Sci. Adv. 4, eaau4869 (2018)), where we use the first Earth-scale quantum sensor network based on optical atomic clocks to search for such dark matter interactions. Although no signal consistent with dark matter fields is found, we considerably improve constraints on the coupling of the dark matter fields to the Standard Model fields.