Project A07: Dynamics of ion Coulomb crystals

Results

In the past funding period the work of project A07 aligned along two major directions. We explored the consequences of the presence of topological defects in zigzag crystals for the transport of vibrational energy and the thermal conductivity. Our analysis showed that strong and robust localization can be observed in the pinned regime of the kink but also revealed the importance of the motional mode spectrum which expresses itself through resonances that alter the non-equilibrium steady state. Since studies regarding the energy transport demand the individual addressing of ions inside the crystal we setup a spatial light modulator (SLM) capable of creating arbitrary intensity patterns for addressing individual ions. To create crystals with kinks in a time-efficient manner we implemented an algorithm for the automatic production of kinks.

A second line of research concerned the corrections to the motional mode spectrum close to phase transitions due to thermal or quantum fluctuations. Taking the linear-to-zigzag transition and the Aubry transition as leading examples we developed in both cases effective models to capture the substantial non-linear dynamics in this regime which lead to an effective stabilisation of the symmetric phase. For the thermal Doppler-cooled regime our model was successfully verified by phonon spectroscopy close to criticality accross the linear to zigzag transition. To gain access to the temperature regime below the Doppler limit we explored in collaboration with B03 fast ground state cooling via quench cooling. We investigated the dependence of the cooling performance on a series of parameters such as the effective linewidth of the electronic transition the cooling is applied to when adiabatically eliminating the auxiliary state.