Ask HN: What has quantum computing achieved so far?

Hacker News Discussion ↗

Quantum computing is widely seen as scientifically promising but still far from delivering practical, everyday benefits. Commenters note that current machines mainly perform narrow tasks (like random circuit sampling or factoring tiny numbers) that showcase “quantum advantage” in principle but have no direct real‑world use, while noise, scaling, and error correction remain major hurdles. Opinions range from skepticism that it will ever be broadly useful to optimism about future applications in cryptography, chemistry, materials science, and optimization, with some pointing out that its biggest concrete impact so far is driving post‑quantum cryptography and related research.

State of the technology

  • No widely accepted practical, everyday applications yet.
  • Current devices can do small, highly specialized tasks (e.g., factoring 15 or 21, random circuit sampling, limited quantum simulations).
  • Several commenters note that even these factoring demos often rely on shortcuts and may not be full, scalable implementations of Shor’s algorithm.
  • Quantum systems remain small, noisy, and hard to scale; error correction and decoherence are central bottlenecks.

Demonstrated capabilities

  • Evidence of “quantum supremacy/advantage” on contrived tasks (random circuit sampling, specific physics problems, quantum annealing speedups) is cited, but others question whether any result is yet incontrovertibly beyond classical reach.
  • Quantum annealers (e.g., D‑Wave) show speedups on some optimization benchmarks but are often viewed as specialized analog devices, not general-purpose quantum computers.

Practical applications & spin‑offs

  • Anticipated first real uses: quantum chemistry, materials science, and quantum simulations where the problem is inherently quantum.
  • Some commenters claim non-public uses in areas like battlefield optimization, materials, batteries, catalysts, and drug discovery, but these are presented as plausible corporate/government work, not documented public results.
  • Spinoffs: improved RF/photonic hardware, quantum sensors, and quantum communications (e.g., expensive, niche quantum key distribution systems).

Cryptography impacts

  • Breaking RSA/ECC via Shor’s algorithm is the main feared application, though large-scale machines needed for 2048–4096-bit keys appear far off.
  • This prospect has already accelerated post-quantum cryptography (lattice-based schemes, NIST process, hybrid PQ/TLS deployments).
  • Discussion of “harvest now, decrypt later” as a reason to migrate early.
  • Symmetric crypto (like AES) is seen as less vulnerable, mainly needing longer keys.

Hype, skepticism, and timelines

  • Optimists: fundamental obstacles have been solved in principle; fault-tolerant machines by ~2035–2040 are “on a clear path”; potential is “civilization-changing.”
  • Skeptics: progress is overhyped, not much beyond 1990 in practical terms; scaling may be physically or economically intractable; likened to fusion or maglev—always decades away.
  • Some view much of the current activity as consultant-driven hype and buzzword chasing.

Conceptual and scientific role

  • Quantum computing deepens understanding of quantum mechanics and the physics of information (e.g., quantum observers, error correction, many-worlds, nonlocality tests).
  • Even if never commercially useful, many see value in QC as a physics experiment and as a bridge between computation theory and quantum physics.