  This paper describes a novel approach to emulate a universal quantum computer
with a wholly classical system, one that uses a signal of bounded duration and
amplitude to represent an arbitrary quantum state. The signal may be of any
modality (e.g. acoustic, electromagnetic, etc.) but this paper will focus on
electronic signals. Individual qubits are represented by in-phase and
quadrature sinusoidal signals, while unitary gate operations are performed
using simple analog electronic circuit devices. In this manner, the Hilbert
space structure of a multi-qubit quantum state, as well as a universal set of
gate operations, may be fully emulated classically. Results from a programmable
prototype system are presented and discussed.
