  We propose to simulate quantum gates by \textit{LC} resonators, where the
amplitude and the phase of the voltage describe the quantum state. By
controlling capacitance or inductance of resonators, it is possible to control
the phase of the voltage arbitrarily. A set of resonators acts as the
phase-shift, the Hadamard and the CNOT gates. They constitute a set of
universal quantum gates. We also discuss an application to an artificial
neuron. As an example, we study a pattern recognition of numbers and alphabets
by evaluating the similarity between an input and the reference pattern. We
also study a colored pattern recognition by using a complex neural network.
