A prototype of quantum von Neumann architecture

TL;DR

This paper proposes a universal quantum von Neumann architecture using entangled states and qubits, demonstrating its potential for fully quantum computing and quantum security, advancing the development of quantum computer systems.

Contribution

It introduces a novel quantum von Neumann architecture model with quantum memory and control units, proving its universality and quantum security features.

Findings

Capable of executing quantum algorithms via gate teleportation

Uses tensor-network states for global configurations

Provides variants of quantum circuits for memory and control roles

Abstract

A modern computer system, based on the von Neumann architecture, is a complicated system with several interactive modular parts. Quantum computing, as the most generic usage of quantum information, follows a hybrid architecture so far, namely, quantum algorithms are stored and controlled classically, and mainly the executions of them are quantum, leading to the so-called quantum processing units. Such a quantum-classical hybrid is constrained by its classical ingredients, and cannot reveal the computational power of a fully quantum computer system as conceived from the beginning of the field. Recently, the nature of quantum information has been further recognized, such as the no-programming and no-control theorems, and the unifying understandings of quantum algorithms and computing models. As a result, in this work we propose a model of universal quantum computer system, the quantum version of the von Neumann architecture. It uses ebits (i.e., Bell states) as elements of the quantum memory unit, and qubits as elements of the quantum control unit and processing unit. As a digital quantum system, its global configurations can be viewed as tensor-network states. Its universality is proved by the capability to execute quantum algorithms based on a program composition scheme via a universal quantum gate teleportation. It is also protected by the uncertainty principle, the fundamental law of quantum information, making it quantum-secure distinct from the classical case. In particular, we introduce a few variants of quantum circuits, including the tailed, nested, and topological ones, to characterize the roles of quantum memory and control, which could also be of independent interest in other contexts. In all, our primary study demonstrates the manifold power of quantum information and paves the way for the creation of quantum computer systems in the near future.