Quantum computing with analog circuits: Hilbert space computing

Abstract

We first point out the practical difficulties of universal quantum computing which may prohibit practical applications as universal computers. Then we show how to apply analog microelectronic circuits to realize the architecture, data processing and parallel computing abilities of quantum computing via Hilbert space computing with analog circuits. Such a Hilbert-space-analog (HSA) computer simulates the Hilbert space and its operators, and it is able to use and test quantum algorithms developed for the real quantum computers. Such a computer would be free of most of the practical difficulties of realizing and running a real quantum computer. This computer can be made universal. It is remarkable that by using the same numbers of transistors as in today's PCs, such a HSA computer can manipulate ∼10 7 analog numbers corresponding to ∼23 qubits, simultaneously, by quantum-parallel processing.