  We report an optical one-way quantum computing experiment with stationary
quantum memory involved. First we create a hybrid four-qubit cluster state with
two qubits propagating as photons and the other two stationary and stored in a
laser-cooled atomic-ensemble quantum memory, and characterize it with
entanglement witness and quantum state tomography. Then, by making use of this
cluster state and fast operations of electro-optic modulators, we realize
memory-assisted feedforward operations and demonstrate deterministic
single-qubit rotation as an example.

Quantum Physics