  We experimentally implement circuits of one and two mode operations on two
motional modes of a single trapped ion. This is achieved by implementing the
required displacement, squeezing, two-mode squeezing, and beamsplitter
operations using oscillating electric potentials applied to the trap
electrodes. The resulting electric fields drive the modes resonantly or
parametrically without the need for optical forces. As a demonstration, we
implement SU(2) and SU(1,1) interferometers with phase sensitivities near the
Cram\'er-Rao bound. We report a maximum sensitivity of a SU(2) interferometer
within $0.67(5)\,$dB of the standard quantum limit (SQL) as well as a single
and two-mode SU(1,1) sensitivity of $5.9(2)\,$dB and $4.5(2)\,$dB below the SQL
respectively.
