  Quantum computing has attracted much attention in recent decades, since it is
believed to solve certain problems substantially faster than traditional
computing methods. Theoretically, such an advance can be obtained by networks
of the quantum operators in universal gate sets, one famous example of which is
formed by CNOT gate and single qubit gates. However, realizing a device that
performs practical quantum computing is tricky. This is because it requires a
scalable qubit system with long coherence time and good controls, which is
harsh for most current platforms. Here, we demonstrate that the information
process based on a relatively stable system -- classical optical system, can be
considered as an analogy of universal quantum computing. By encoding the
information via the polarization state of classical beams, the optical
computing elements that corresponds to the universal gate set are presented and
their combination for a general information process are theoretically
illustrated. Taking the analogy of two-qubit processor as an example, we
experimentally verify that our proposal works well. Considering the potential
of optical system for reliable and low-energy-consuming computation, our
results open a new way towards advanced information processing with high
quality and efficiency.
