Quantum Supremacy vs Quantum Advantage vs Utility: What the Terms Mean
Three terms, three different bars
| Term | Meaning | Does the task matter? |
|---|---|---|
| Quantum supremacy | A quantum computer performs a task that is practically impossible for any classical computer | No. The task can be useless, designed to be hard for classical machines |
| Quantum advantage | A quantum computer solves a useful problem better (faster, cheaper or more accurately) than the best classical method | Yes |
| Quantum utility | A quantum computer produces useful results at a scale where exact classical checking is hard, with the answers trusted for other reasons | Yes, and the bar is lower than full advantage |
Many researchers prefer "advantage" to "supremacy" because supremacy suggests quantum machines are better at everything, which is wrong. See the longer guide and advantage vs utility.
What happened in 2019?
In October 2019 Google researchers reported in Nature that their 53 qubit Sycamore processor sampled the output of a random quantum circuit in about 200 seconds, a task they estimated would take the best classical supercomputer thousands of years, and described this as quantum supremacy. IBM researchers responded with a preprint arguing that, by using secondary storage, a classical supercomputer (Summit at Oak Ridge National Laboratory) could simulate such circuits "in a matter of days" (arXiv:1910.09534). The disagreement was about how to count the best classical cost. Later classical algorithms narrowed the gap further. See the Google and IBM rebuttal in detail.
What about Willow in 2024?
In December 2024 Google announced its 105 qubit Willow chip and said it completed a random circuit sampling benchmark in under five minutes that it estimates would take a supercomputer 10 septillion years. This is again a benchmark built to be hard for classical computers and a company estimate. The more significant result in that announcement was error correction where errors fell as the code grew, a step toward reliable machines. See Willow and Quantum Echoes.
Why are such claims often disputed?
- Classical algorithms keep improving. A task that looks impossible today may be solved by a better classical method next year.
- The task may be artificial. Random circuit sampling has no known practical use, so it shows the hardware works rather than that quantum helps with real problems.
- Noise. A noisy machine's output can sometimes be imitated by a cheaper classical model of that noise.
- Verification. If no classical computer can check the answer, how do we know it is right? Some experiments are designed so the answer can be validated in other ways.
How can you judge a claim?
- Is it peer reviewed, and is the paper linked?
- What is the task, and is it useful or a benchmark?
- What classical method is it compared with, and was that the best known?
- Has it been reproduced, or has a classical rebuttal appeared?
- Is it a result, or a roadmap promise?
The same questions help with market news: how to read quantum computing stocks without hype. For hardware background see what is a qubit.
What does this mean for crypto and QNT?
Supremacy experiments do not break encryption. Breaking today's public key cryptography needs a large, error corrected machine running Shor's algorithm, which is a different and much larger milestone. See blockchain vs quantum computing. QUANTUM (QNT) is a community token on Solana with a quantum theme and does not perform quantum computation.
Sources and further reading
- Nature (2019): Quantum supremacy using a programmable superconducting processor
- Pednault et al.: Leveraging Secondary Storage to Simulate Deep 54-qubit Sycamore Circuits (arXiv:1910.09534)
- Google: Meet Willow, our state-of-the-art quantum chip
- Nature: Quantum error correction below the surface code threshold
- Preskill: Quantum Computing in the NISQ era and beyond (arXiv)
- Shor (arXiv:quant-ph/9508027)
Checked 2026-10-12. Company claims are the companies' own and roadmaps are plans, so check the primary sources. This is education, not investment or security advice. QUANTUM (QNT) is an independent community token on Solana and is not affiliated with Quantinuum (Nasdaq: QNT) or Quant Network (QNT on Ethereum).
Frequently asked questions
What is the difference between quantum supremacy and quantum advantage?
Supremacy is a quantum computer doing any task, even a useless one, beyond practical classical reach. Advantage is doing a useful task better than the best classical method.
Did Google achieve quantum supremacy?
Google claimed it in 2019 with its Sycamore chip. IBM argued the task could be simulated classically in days, and the claim has been debated since.
Do these experiments break encryption?
No. Breaking public key cryptography needs a large, error corrected machine running Shor's algorithm, which is a different milestone.
Is QNT a quantum computing project?
No. QUANTUM (QNT) is a community token on Solana with a quantum theme.
Next read
Quantum Supremacy vs Quantum Advantage ExplainedWhat the terms quantum supremacy and quantum advantage mean, and why headline claims are often debated.Read nextAlso useful: Google's Supremacy Claim, IBM's Rebuttal and the Classical Catch-Up: A Case Study | Advantage, Utility, Supremacy: Reading the Words, With IBM's 2023 Experiment as the Test Case | Google Quantum AI: Willow, Error Correction and Quantum Echoes
Educational content, not financial advice. QUANTUM (QNT) is independent of Quantinuum (Nasdaq: QNT) and Quant Network (QNT on Ethereum). Live chart | Token facts