The Quantum House Of Cards

TL;DR

This paper critically examines the technological challenges across the entire quantum computing stack, from algorithms to hardware, highlighting the gap between current capabilities and the promises of quantum computing.

Contribution

It provides a comprehensive overview of the technical hurdles in building practical quantum computers, emphasizing the need for advancements across multiple layers.

Findings

Quantum hardware struggles with basic operations like multiplication.

Quantum error correction is a crucial but challenging layer.

Current quantum computers are far from achieving practical applications.

Abstract

Quantum computers have been proposed to solve a number of important problems such as discovering new drugs, new catalysts for fertilizer production, breaking encryption protocols, optimizing financial portfolios, or implementing new artificial intelligence applications. Yet, to date, a simple task such as multiplying 3 by 5 is beyond existing quantum hardware. This article examines the difficulties that would need to be solved for quantum computers to live up to their promises. I discuss the whole stack of technologies that has been envisioned to build a quantum computer from the top layers (the actual algorithms and associated applications) down to the very bottom ones (the quantum hardware, its control electronics, cryogeny, etc.) while not forgetting the crucial intermediate layer of quantum error correction.