Provable bounds for noise-free expectation values computed from noisy samples
Open accessAbstract
Quantum computing has emerged as a powerful computational paradigm capable of solving problems beyond the reach of classical computers. However, today’s quantum computers are noisy, posing challenges to obtaining accurate results. Here, we explore the impact of noise on quantum computing, focusing on the challenges in sampling bit strings from noisy quantum computers and the implications for optimization and machine learning. We formally quantify the sampling overhead to extract good samples from noisy quantum computers and relate it to the layer fidelity, a metric to determine the performance of noisy quantum processors. Further, we show how this allows us to use the conditional value at risk of noisy samples to determine provable bounds on noise-free expectation values. We discuss how to leverage these bounds for different algorithms and demonstrate our findings through experiments on real quantum computers involving up to 127 qubits. The results show strong alignment with theoretical predictions. In this study, the authors investigate the impact of noise on quantum computing with a focus on the challenges in sampling bit strings from noisy quantum computers, which has implications for optimization and machine learning.
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The CVaR metric has been identified as more robust against noise when used as an objective function in quantum computations.
“This metric has been identified as more robust against noise when used as an objective function in quantum computations [13].”
From Towards secondary structure prediction of longer mRNA sequences using a quantum-centric optimization scheme (2025) · cites this paper as [13]
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Challenges and opportunities in quantum optimization
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“For example, the conditional value at risk 74,75 does not average over the objective values corresponding to all samples obtained from measuring a quantum state, but sorts them and only takes the average over the best α -fraction of samples, for a predefined α ∈ [0, 1].”
Self-citationBias-field digitized counterdiabatic quantum algorithm for higher-order binary optimization
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“Rather than taking the entire distribution of samples into account ( α = 1), we fi rst sort them in terms of energy so that E k ≤ E k + 1 .”
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“This metric has been identified as more robust against noise when used as an objective function in quantum computations [13].”
- Authors
- Barron, S. V., Egger, D. J., Pelofske, E., Bärtschi, A., Eidenbenz, S., Lehmkuehler, M., & Woerner, S.
- Affiliations
- IBM (United States) (US)
- IBM Research - Zurich (CH)
- Los Alamos National Laboratory (US)
- University of Basel (CH)
- Corresponding author
- Woerner, Stefan
- Venue
- Nature Computational Science
- Published
- 2024-11-01
- Volume
- 4
- Issue
- 11
- Pages
- 865-875
- ISSN
- 2662-8457 (ISSN-L)
- PMC
- PMC11578887
- OpenAlex
- W4403984119
- Cited by
- 25
- References
- 11
- Citations by year
- 2026: 9 · 2025: 10 · 2024: 5 · 2023: 1
- FWCI
- 3.54
- Type
- journal article
- Language
- en
- Open access
- hybrid
- doi.org
- Licence
- Locations
- Nature Computational Science (publishedVersion, cc-by-nc-nd)
- PubMed Central (publishedVersion, cc-by-nc-nd)
- PubMed (publishedVersion)
- arXiv (Cornell University) (submittedVersion, cc-by)
- OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) (submittedVersion)
- arXiv (Cornell University) (cc-by)
- Funders
- National Science Foundation (89233218CNA000001)
- U.S. Department of Energy (#89233218CNA000001)
- Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung (214919)
- National Nuclear Security Administration (89233218C-NA000001, No. 89233218CNA000001)
- Los Alamos National Laboratory (89233218CNA 000001)
- Topics
- Physical Sciences › Computer Science › Artificial Intelligence › Quantum Computing Algorithms and Architecture
- Physical Sciences › Computer Science › Artificial Intelligence › Quantum Information and Cryptography
- Physical Sciences › Physics and Astronomy › Atomic and Molecular Physics, and Optics › Quantum many-body systems
- Keywords
- noisy quantum computers, sampling overhead, conditional value at risk, quantum sampling, quantum optimization, quantum machine learning
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