How big is a quantum computer?

TL;DR

This paper examines the physical resource constraints in quantum computing, revealing that classical wave-based computers are as resource-efficient as quantum particle-based ones due to readout limitations.

Contribution

It highlights overlooked physical constraints in quantum readout, establishing a lower bound on resources and comparing classical wave and quantum particle computing efficiency.

Findings

Classical wave computers are as resource-efficient as quantum particle computers.

Physical readout constraints set a fundamental resource lower bound.

Quantum readout limitations impact the perceived advantage of quantum computing.

Abstract

Accounting for resources is the central issue in computational efficiency. We point out physical constraints implicit in information readout that have been overlooked in classical computing. The basic particle-counting mode of read-out sets a lower bound on the resources needed to implement a quantum computer. As a consequence, computers based on classical waves are as efficient as those based on single quantum particles.