  We propose an optical parallel computation similar to quantum computation
that can be realized by introducing pseudorandom phase sequences into classical
optical fields with two orthogonal modes. Based on the pseudorandom phase
sequences, we first propose a theoretical framework of "phase ensemble model"
referring from the concept of quantum ensemble. Using the ensemble model, we
further demonstrate the inseparability of the fields similar to quantum
entanglement. It is interesting that a N2^N dimensional Hilbert space spanned
by N optical fields is larger than that spanned by N quantum particles. This
leads a problem for our scheme that is not the lack of resources but the
redundancy of resources. In order to reduce the redundancy, we propose a
special sequence permutation mechanism to efficiently imitate certain quantum
states, including the product state, Bell states, GHZ state and W state. For
better fault tolerance, we further devise each orthogonal mode of optical
fields is measured to assign discrete values. Finally, we propose a generalized
gate array model to imitate some quantum algorithms, such as Shor's algorithm,
Grover's algorithm and quantum Fourier algorithm. The research on the optical
parallel computation might be important, for it not only has the potential
beyond quantum computation, but also provides useful insights into fundamental
concepts of quantum mechanics.
