Quantum computing bombshells that are not April Fools

Original Article ↗ Hacker News Discussion ↗

Current capabilities and limitations

  • Present-day quantum computers are noisy and can only run short, simple algorithms; even basic arithmetic at useful scales is not yet practical.
  • Error correction is a major bottleneck; large overhead is required before meaningful algorithms (e.g., factoring large numbers) are feasible.
  • Some argue today’s devices are “basically worthless” for commercial workloads; others see concrete progress in simulating quantum systems beyond classical reach and generating nontrivial states.

Cloud access and simulation

  • IBM offers rentable QC time; users report good documentation and UX, but the free tier has been reduced.
  • Simulating many qubits classically becomes exponentially expensive in RAM (e.g., ~64 GB for 32 qubits, ~1 TB for 36), so real hardware can explore regimes simulators can’t.
  • However, no rented QC has yet beaten optimized classical CPU/GPU implementations on benchmark tasks.

Applications, research, and commercialization

  • Current buyers of full-stack systems are mainly universities, research institutes, and HPC centers exploring integration and future workflows.
  • QC is compared to large scientific projects (space missions, colliders): low or negative near-term profit but meaningful progress and employment.

Investing and SPACs

  • Several QC firms are going public via SPACs; some view their stocks as long-term “lottery tickets” with 5–20 year horizons.
  • Skepticism exists that end-users will see profit soon and that someone will be “left holding the bag.”

Cryptography, Bitcoin, and post-quantum transition

  • Quantum computers threaten asymmetric crypto (RSA/ECC) via Shor’s algorithm; symmetric ciphers are less affected (Grover-style speedup).
  • Serious financial institutions are reported to be working on post-quantum strategies, with long migration timelines.
  • Bitcoin is seen as particularly vulnerable because it relies solely on cryptography; banks can fall back on KYC and operational controls.
  • Proposals to “rescue” Bitcoin (e.g., precommitments to post-quantum keys with delays and fees) face coordination, DoS, and UX challenges.
  • Some argue breaking Bitcoin would coincide with broader crypto-systemic failure; others stress that banks can rekey more easily than blockchains.

Custom “quantum-resistant” blockchains

  • One project claims a hand-written, quantum-resistant signature scheme and codebase; others warn that rolling custom crypto without expert review is risky.
  • Debate touches on “hedging” against library backdoors versus the need for expert validation.

Perception, hype, and timelines

  • Some see steady algorithmic and hardware progress bringing factoring thresholds closer; others dismiss frequent “breakthrough” headlines as premature hype.
  • Comparisons are made to fusion and self-driving cars: real research, long road to practical impact.

Miscellaneous notes

  • Blog hosting the article is criticized for poor mobile responsiveness and lack of reader mode support.
  • A technical aside mentions selective observations and the quantum Zeno effect as relevant to new error-correction ideas.