Speaker
Description
Precise control over the motional states is a cornerstone of modern trapped-ion experiments, where reaching the motional ground state is essential for high-fidelity quantum gates or the suppression of systematic shifts in precision metrology. In particular, the preparation of ions in the motional ground state of mixed-species ion crystals is a prerequisite for quantum logic spectroscopy (QLS). QLS allows for the interrogation of atomic systems that lack the cycling transitions necessary for direct laser cooling and state detection.
An example of such systems are highly charged ions (HCIs), which are sensitive probes for testing fundamental physics and searching for physics beyond the Standard Model. However, these ions typically feature level structures that are inaccessible to current laser technology, as their primary transitions lie deep in the ultraviolet regime."
To shield the ions from magnetic field noise we use a superconducting resonator Paul trap. A significant challenge in our setup is that the trap operates in an intermediate Lamb-Dicke regime, with the Lamb-Dicke parameter $\eta$ reaching up to $0.7$ for a single $^{9}\text{Be}^{+}$ ion.
Building upon our previous success in demonstrating ground-state cooling of a single $^{9}\text{Be}^{+}$ ion in this regime , we have extended these protocols to a two $^{9}\text{Be}^{+}$ ion crystal. We performed a systematic evaluation of optimal pulse durations, pulse ordering, and a comparison between pulsed and continuous sideband cooling to maximize the ground-state population.
We report on our current progress towards achieving ground-state cooling of the axial motional modes of a $^{9}\text{Be}^{+}$-$^{40}\text{Ar}^{13+}$ mixed-species crystal. This includes a detailed characterization of the crystal's mode structure and the optimization of cooling sequences. These advancements represent an essential step towards QLS on HCIs, paving the way for spectroscopic tests of fundamental physics.
| Academic level | PhD student |
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