Testing Fundamental Physics Tender

Grant agreement ID 101019987Start date 1 January 2022End date 31 December 2026Overall budget 2 445 950 ObjectivePrecision spectroscopy of highly charged ions HCI provides insight into atomic systems in which electrons are highly correlated strongly relativistic and experience strong internal fields. Thus HCI are excellent systems to probe and refine our understanding of physics under these extreme conditions. They are the most sensitive known atomic species to probe for possible changes in fundamental constants and offer advantageous properties to study coupling of hypothetical dark matter fields to normal matter. For these applications high-precision optical spectroscopy of HCI is required. In the past the spectroscopic resolution of optical transitions in HCI was limited by Doppler-broadening to hundreds of megahertz. We have recently demonstrated the first hertz-level laser spectroscopy of an optical fine-structure transition in highly charged argon using sympathetic cooling and quantum logic with a co-trapped logic ion in a Paul trap improving the spectroscopic precision by nine orders of magnitude compared to the previous state-of-the-art. Here we propose to further develop quantum techniques for controlling HCI and to push spectroscopic resolution in order to realise next generation optical clocks based on promising reference transitions in HCI. We will employ these novel types of optical clocks to advance our understanding of atomic structure and to probe for physics beyond the standard model. Sub hertz-level isotope shift spectroscopy of highly charged calcium ions will be performed to improve current bounds on hypothetical fifth forces that couple neutrons and electrons. Furthermore we will perform optical clock-type spectroscopy on HCI that offer up to a 20-fold higher sensitivity to a possible change in the fine-structure constant and a non-gravitational coupling between dark matter and normal matter than existing clocks. Through frequency comparisons with other clocks we will improve bounds on these new physics effects.