Trapped ions

The group studies individual atomic ions confined in radio-frequency electromagnetic traps and cooled with laser light to near their motional ground state. In this exceptionally clean and well-isolated setting, the internal electronic states and the quantized collective motion of the ions can be coherently controlled with laser and microwave fields, making trapped ions one of the most precisely manipulable quantum systems available. The work spans the coherent control of single qubits and small ion strings, the engineering of entanglement through the shared motional modes, and the characterization of the noise processes that ultimately limit coherence.

These capabilities serve two broad goals. As a platform for quantum information, trapped ions support high-fidelity quantum logic gates and serve as a testbed for understanding and suppressing decoherence. As precision instruments, the same long-lived atomic states enable searches for tiny shifts in transition frequencies that probe fundamental symmetries, possible variation of fundamental constants, and physics beyond the Standard Model. A further line of work brings cold ions into contact with ultracold neutral atoms, opening a controlled regime for studying atom-ion collisions, chemistry, and the interplay between charged and neutral quantum matter.