  The three-electron configuration of gate-defined double quantum dots encodes
a promising qubit for quantum information processing. I propose a two-qubit
entangling gate using a pulse-gated manipulation procedure. The requirements
for high-fidelity entangling operations are equivalent to the requirements for
the pulse-gated single-qubit manipulations that have been successfully realized
for Si QDs. This two-qubit gate completes the universal set of all-pulse-gated
operations for the three-electron double-dot qubit and paves the way for a
scalable setup to achieve quantum computation.
