  We present some deterministic schemes to construct universal quantum gates,
that is, controlled- NOT, three-qubit Toffoli, and Fredkin gates, between
flying photon qubits and stationary electron-spin qubits assisted by quantum
dots inside double-sided optical microcavities. The control qubit of our gates
is encoded on the polarization of the moving single photon and the target
qubits are encoded on the confined electron spins in quantum dots inside
optical microcavities. Our schemes for these universal quantum gates on a
hybrid system have some advantages. First, all the gates are accomplished with
the success probability of 100% in principle. Second, our schemes require no
additional qubits. Third, the control qubits of the gates are easily
manipulated and the target qubits are perfect for storage and processing.
Fourth, the gates do not require that the transmission for the uncoupled cavity
is balanceable to the reflectance for the coupled cavity, in order to get a
high fidelity. Fifth, the devices for the three universal gates work in both
the weak coupling and the strong coupling regimes, and they are feasible in
experiment.
