Quantum computing debated in The Financial Times

Criticism of quantum computing hype and a rebuttal recently appeared in The Financial Times. The first article argues that even "well-established" applications of future quantum computers - breaking encryption and efficient quantum chemistry calculations - may not be useful in practice. The second article notes that even though there is tremendous hype, there is also slow but steady progress in scaling up quantum processors and understanding which quantum algorithms might provide value and which will not.

It is worth emphasizing that quantum technologies are much broader than quantum computing. For example, quantum research in Singapore are also encompasses quantum communications and quantum sensing. While these areas a seen as being closer to useful commercial applications, there are still some important caveats:

Quantum communication technologies are often marketed as the solution to the problem of future quantum computers being able to break widely-used public key cryptography schemes, with quantum key distribution providing unbreakable encryption protected by the laws of physics. The reality is that sharing of encryption keys is just one part of a secure communications network; a far bigger problem is authentication - how can you prove the other party is who they claim to be? Indeed, the vast majority of data breaches or online scams are not due to encryption protocols being broken or passwords being hacked, but rather are a result of phishing attacks where the victim is tricked into believing the attacker is someone else. The UK's National Cyber Security Centre's position on quantum communication technologies is:

"Given the specialised hardware requirements of QKD over classical cryptographic key agreement mechanisms and the requirement for authentication in all use cases, the NCSC does not endorse the use of QKD for any government or military applications, and cautions against sole reliance on QKD for business-critical networks, especially in Critical National Infrastructure sectors.

In addition, we advise that any other organisations considering the use of QKD as a key agreement mechanism ensure that robust quantum-safe cryptographic mechanisms for authentication are implemented alongside them."

Quantum sensing promises the ability to perform measurements with precision unattainable using classical devices. This encompasses many well-established approaches based on quantum coherence, including SQUIDs, atomic clocks, atomic gravimeters, and squeezed light interferometers, and more speculative ideas based on large-scale quantum entanglement. The latter entanglement-based approaches have however attracted criticism (see for example this preprint).

In all these examples - quantum computing, quantum communications, and quantum sensing - useful technologies will not emerge from quantum researchers working in isolation. Collaboration with researchers working in other disciplines and industry is essential to keep quantum "solutions" honest and ensure that we are solving problems that need to be solved, and to establish that quantum techniques provide a better solution than well-established classical methods.