  We investigate a hybrid quantum system involving spin qubits, based on the
spins of electrons confined in quantum dots, and topological qubits, based on
Majorana fermions. In such a system, gated control of the charge on the quantum
dots allows transfer of quantum information between the spin and topological
qubits, and the topological system can be used to facilitate transfer of spin
qubits between spatially separated quantum dots and to initialize entangled
spin-qubit pairs. Here, we show that the coupling to the topological system
also makes it possible to perform entangling two-qubit gates on spatially
separated spin qubits. The two-qubit gates are based on a combination of
topologically protected braiding operations, gate-controlled charge transfer
between the dots and edge Majorana modes, and measurements of the state of the
topological qubits.
