Seven Quantum Computing Myths For Executives

Senior leaders hear about quantum computing from vendors, board members, consultants and the press, and the messages rarely agree. One week a new chip is said to make every computer obsolete; the next, an expert says nothing useful will happen for decades. Both extremes lead to poor decisions: panic spending on one side, neglect of a real migration task on the other.

This article sets out seven myths that come up repeatedly in boardrooms, and what the evidence in this series says instead. It is a summary for busy readers. Each point links to the article with the detail.

Myths About How Quantum Computers Work

Myth one: quantum computers try every answer at once. A group of qubits can hold a superposition over a vast number of values, but measuring it returns one random result. Speed-ups come from interference, which steers the odds towards the right answer, and that only works for problems with a particular kind of mathematical structure.¹ See What A Qubit Is, And What It Is Not.

Myth two: quantum computers will replace ordinary computers. NIST’s explainer says they will not replace classical computers but work alongside them, and notes that many experts expect them to live in computing centres, national laboratories and universities rather than on desks.² Email, databases, payments and most business software have no structure for a quantum computer to exploit.

Myth three: quantum computing will supercharge AI. The pairing of quantum and AI is common in marketing. None of the major beyond-classical claims reviewed in this series involves training or running a machine learning model; they involve sampling benchmarks and physics simulations.³ Research on quantum machine learning continues. A 2022 experiment showed a quantum processor learning about quantum systems from far fewer experiments than a conventional approach,⁴ and a 2026 preprint co-written by Google researchers proves theoretical advantages for processing very large classical data sets.⁵ Neither shows a speed-up for the AI tools businesses use today, so leaders should not budget on the assumption of a quantum boost to AI.

Myths About Progress

Myth four: more qubits means a more powerful machine. Error rates matter more than counts. Google’s Willow chip mattered because its error correction improved as the code grew, not because of its 105 qubits.⁶ Logical qubit counts from different vendors are also measured in different ways, some with errors corrected and some with errors only detected and the affected runs discarded.⁷ See Noise, Error Rates And Why Error Correction Decides Everything.

Myth five: “quantum advantage” means the threat to encryption has arrived. Advantage claims so far concern narrow tasks such as random circuit sampling, which Google itself says has yet to show commercial applications.⁶ Several earlier claims were later matched by classical computers. None involved breaking encryption. See Quantum Advantage, Supremacy And The Claims That Did Not Survive.

Myths About Security

Myth six: quantum computers will break all encryption. The risk is concentrated in public-key cryptography, the RSA and elliptic curve algorithms used for key exchange and digital signatures, because Shor’s algorithm attacks the mathematics behind them.⁸ Symmetric encryption such as AES is far less exposed. NIST’s draft transition guidance says its approved symmetric algorithms with at least 128 bits of classical security, which includes AES-128 and AES-256, are believed to meet at least the lowest of its post-quantum security categories.⁹

Myth seven: we can wait until someone announces a quantum computer that can break RSA. Nobody can name that date, and published estimates of the machine required have fallen: from 20 million physical qubits in 2019 to under a million in a 2025 preprint by the same Google researcher,¹⁰ and to under 100,000 in a 2026 preprint that uses a different kind of error correction and assumes a run of about a month.¹¹ Meanwhile, attackers can record encrypted data today and decrypt it later, a risk explained in The Quantum Threat. Government bodies have set or proposed target dates accordingly. The UK National Cyber Security Centre, for example, expects organisations to finish migrating to post-quantum cryptography by 2035.¹²

A Quick Test For Quantum Headlines

When a new announcement reaches the board, these questions help decide whether it should change anything. The filter is deliberately narrow, and it starts with official guidance, because a new standard or a revised national timeline can move your deadlines even when the technology has not changed. Most quantum news, including genuine scientific progress, concerns hardware quality, error correction or benchmark results, and none of that alters a migration plan by itself. What would alter it is credible evidence that breaking public-key cryptography has become cheaper or nearer, such as a new peer-reviewed resource estimate or a government body revising its guidance.

None of this calls for alarm. It calls for a steady programme: know where your organisation uses public-key cryptography, decide which data must stay secret longest and plan the move to the new standards described in Post-Quantum Cryptography. The practical steps are in Preparing For Migration.