UC Berkeley

The electromagnetic force is one of the four basic interactions discovered in nature and it plays an essential role in determining the internal properties of most matter seen in daily life. In this dissertation, we present the endeavor on exploiting electromagnetic fields to actively control the dynamics of various nanoscopic matter, including atomic ion rings, monolayer semiconductors, and nanomechanical membranes. The achieved controls open up unique opportunities to study fundamental many-body quantum physics and to facilitate information and energy transfer processes at the nanoscale.

This dissertation consists of three sets of experiments. 1. We design and fabricate a surface-electrode Paul trap and confine up to fifteen 40Ca+ ions into a microscopic ring using radio-frequency electric fields. The achieved unprecedented circular symmetry enables the first observation of localization-delocalization transitions of ion rings at millikelvin temperatures. 2. We propose and demonstrate a scheme to couple electron valley degree-of-freedom with macroscopic mechanical motion using a magnetic field gradient perpendicular to suspended monolayer semiconducting transition metal dichalcogenides (for example MoS2). Direct transduction of valley excitation into mechanical states is realized for the first time. 3. We perform the first experiment to probe and manipulate the phonon energy transfer driven by quantum fluctuations of electromagnetic fields (the Casimir effect). With a delicate approach to place two nanomechanical membranes parallel and close to each other, we realize the first strong Casimir phonon coupling condition and thus observe the thermal energy exchange across vacuum between individual phonon modes.