  Microwave near-field quantum control of spin and motional degrees of freedom
of 25Mg+ ions can be used to generate two-ion entanglement, as recently
demonstrated in Ospelkaus et al. [Nature 476, 181 (2011)]. Here, we describe
additional details of the setup and calibration procedures for these
experiments. We discuss the design and characteristics of the surface-electrode
trap and the microwave system, and compare experimental measurements of the
microwave near-fields with numerical simulations. Additionally, we present a
method that utilizes oscillating magnetic-field gradients to detect micromotion
induced by the ponderomotive radio-frequency potential in linear traps.
Finally, we discuss the present limitations of microwave-driven two-ion
entangling gates in our system.
