Cited by 62Quantum Computing Algorithms and ArchitectureQuantum Information and CryptographyQuantum many-body systems

Constrained quantum optimization for extractive summarization on a trapped-ion quantum computer

Open access
Niroula, Pradeep, Shaydulin, Ruslan, Yalovetzky, Romina, Minssen, Pierre, Herman, Dylan, Hu, Shaohan, Pistoia, Marco·2022·Scientific Reports

Abstract

Realizing the potential of near-term quantum computers to solve industry-relevant constrained-optimization problems is a promising path to quantum advantage. In this work, we consider the extractive summarization constrained-optimization problem and demonstrate the largest-to-date execution of a quantum optimization algorithm that natively preserves constraints on quantum hardware. We report results with the Quantum Alternating Operator Ansatz algorithm with a Hamming-weight-preserving XY mixer (XY-QAOA) on trapped-ion quantum computer. We successfully execute XY-QAOA circuits that restrict the quantum evolution to the in-constraint subspace, using up to 20 qubits and a two-qubit gate depth of up to 159. We demonstrate the necessity of directly encoding the constraints into the quantum circuit by showing the trade-off between the in-constraint probability and the quality of the solution that is implicit if unconstrained quantum optimization methods are used. We show that this trade-off makes choosing good parameters difficult in general. We compare XY-QAOA to the Layer Variational Quantum Eigensolver algorithm, which has a highly expressive constant-depth circuit, and the Quantum Approximate Optimization Algorithm. We discuss the respective trade-offs of the algorithms and implications for their execution on near-term quantum hardware.

AI snapshot

Written from the paper’s full text.

TL;DR

The paper demonstrates XY-QAOA with a Hamming-weight-preserving XY mixer for extractive summarization on the Quantinuum H1-1 trapped-ion quantum computer, using up to 20 qubits and two-qubit gate depth up to 159 (765 two-qubit gates). It argues that constraints should be encoded directly into the quantum circuit because unconstrained QAOA forces a difficult trade-off between in-constraint probability and solution quality.

Key findings

  • XY-QAOA was executed on H1-1 with up to 20 qubits, full-circuit two-qubit depth 159, and two-qubit gate count 765; the 20-qubit Dicke-state preparation alone required two-qubit depth 95 and 347 two-qubit gates.
  • XY-QAOA natively preserves the Hamming-weight constraint, giving in-constraint probability of one in the noiseless case; hardware noise caused out-of-constraint samples, with 20-qubit XY-QAOA outputs including bitstrings as far as 10 bitflips away, while short L-VQE circuits included only bitstrings one or two bitflips away.
  • QAOA gave a relatively high approximation ratio but very low in-constraint probability; for 14 qubits its in-constraint probability was below random guess due to parameter choice. L-VQE achieved high approximation ratio and in-constraint probability on the modest 14- and 20-qubit problems, but its expressiveness makes parameters hard to optimize as qubit count grows.
  • A Pareto frontier for QAOA parameters showed the trade-off between approximation ratio and in-constraint probability; optimizing the penalized objective (6) can lead to an approximation ratio equal to random guess for a 20-qubit instance.

Methods

  • Extractive summarization was formulated as McDonald’s NP-hard constrained optimization: maximize sentence centrality while penalizing pairwise redundancy, with a fixed summary length. Instances came from CNN/DailyMail articles (just over 300k unique news articles), using two sets of 10 instances and executions on 14 and 20 qubits; BERT sentence embeddings computed similarities and tf-idf computed centralities.
  • QAOA, XY-QAOA, and L-VQE were compared. Parameters were optimized in noiseless simulation, then circuits were executed on the Quantinuum H1-1 device with 2000 shots and on an H1-1 emulator; Qiskit was used for circuit manipulation and simulation, and Quantinuum’s t transpiler for hardware compilation. No error mitigation was applied.
  • Metrics were approximation ratio (Eq. 8) and in-constraint probability, estimated as the ratio of in-constraint samples to total samples. For unconstrained solvers, the penalty weight was chosen so in-constraint binary strings had greater cost than out-of-constraint strings. XY-QAOA’s initial Dicke state was prepared using a divide-and-conquer short-depth method targeting all-to-all connectivity.

Limitations

  • Stated: XY-QAOA requires deeper circuits than QAOA and L-VQE because of the XY mixer and Dicke-state preparation, incurring significant cost before optimization; hardware noise in initial-state preparation and deeper circuits reduces in-constraint probability.
  • Stated: L-VQE’s expressiveness makes parameters hard to optimize and may suffer barren plateaus as qubit count grows; QAOA’s parameter optimization must trade off in-constraint probability and solution quality, which is hard in general.
  • Stated/evident: hardware XY-QAOA results are based on only three 14-qubit and three 20-qubit instances due to high circuit depth and running time, and no error mitigation was used. Evident from the provided text: several numerical values, including some approximation ratios and instance sizes, are omitted in the text as given.

Model-written summary. Check it against the paper before relying on it.

Integrity signals

Registry

Crossref · 10.1038/s41598-022-20853-w

Cites

77 of 77 references verified0 citation errors · 0 not checkable

Statistics

Nothing to recompute.

Claims the paper makes

0 of 13 cited sources checked · 0 supported · 0 flagged

  • Findingown data

    The results on hardware are on average at least as good as those obtained from the emulator.

    “Additionally, we observe that the results on hardware are on average at least as good as those obtained from the emulator, making us confident that the emulator gives a good lower bound on the solution quality that can be expected on hardware.”
    Quote in the paperSubstantial claim
  • Findingown data

    The noise is sufficiently low so that the XY-QAOA output distribution is still concentrated on the in-constraint subspace.

    “At the same time, the noise is sufficiently low so that the XY-QAOA output distribution is still concentrated on the in-constraint subspace.”
    Quote in the paperSubstantial claim
  • Findingreasoning

    For the modestly sized problems considered in this work, the L-VQE parameters can be optimized to obtain solutions with very high approximation ratio and in-constraint probability.

    “As we consider modestly sized problems in this work, we are able to optimize the parameters and obtain solutions with very high approximation ratio and in-constraint probability.”
    Quote in the paperSubstantial claim
  • Findingnone given

    A significant part of the two-qubit gate depth of the XY-QAOA circuit comes from the circuit preparing the initial Dicke state.

    “For the XY-QAOA circuit, a significant part of the two-qubit gate depth comes from the circuit preparing the initial state, which is a uniform superposition of all in-constraint states (Dicke state).”
    Quote in the paperSubstantial claim
  • Findingown data

    The execution of XY-QAOA on the Quantinuum H1-1 processor used all 20 qubits of H1-1.

    “We use all 20 qubits of H1-1 and execute circuits with two-qubit gate depth of up to 159 and two-qubit gate count of up to 765, which is the largest such demonstration to date.”
    Quote in the paperSubstantial claim
  • Classified as probably not a substantial claim. 16
  • May combine two claims. 15
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingown data

    The in-constraint probability of QAOA is below random guess for 14 qubits due to the choice of parameters.

    “The in-constraint probability of QAOA is below random guess for 14 qubits due to the choice of parameters; see discussion in “Quantum circuit needs to preserve constraints”.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    For the short L-VQE circuits, the amount of noise accumulated during circuit execution is small, and only bitstrings that are one or two bitflips away are included in the output.

    “Note that for the short L-VQE circuits, the amount of noise accumulated during the circuit execution is small, and only the bitstrings that are one or two bitflips away are included in the output.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Findingown data

    As noise is added, the in-constraint probability decreases and the output begins to include out-of-constraint bitstrings.

    “We can see that as the noise is added, the in-constraint probability decreases and the output begins to include out-of-constraint bitstrings.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Findingreasoning

    QAOA gives a relatively high approximation ratio but a very low in-constraint probability.

    “We begin by noting that QAOA gives a relatively high approximation ratio, but a very low in-constraint probability.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Findingnone given

    Initial state preparation for QAOA and L-VQE requires no two-qubit gates.

    “Initial state preparation for QAOA and L-VQE requires no two-qubit gates.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Premisecitation

    The expressiveness of the L-VQE circuit makes the parameters hard to optimize, both due to their high number and due to gradients vanishing as the number of qubits grows in some cases.

    “At the same time, the expressiveness of L-VQE circuit makes the parameters hard to optimize, both due to their high number and due to the gradients vanishing as the number of qubits grows in some cases44,45.”
    Quote in the paperSubstantial claim0 of 2 sources checked
    • cites [44] McClean, J. R., Boixo, S., Smelyanskiy, V. N., Babbush, R. & Neven, H. Barren plateaus in quantum neural network training landscapes. Nat. Commun.https://doi.org/10.1038/s41467-018-07090-4 (2018). source

      Not checked in the free run.

    • cites [45] Holmes, Z., Sharma, K., Cerezo, M. & Coles, P. J. Connecting ansatz expressibility to gradient magnitudes and barren plateaus. PRX Quantum.https://doi.org/10.1103/prxquantum.3.010313 (2022). source

      Not checked in the free run.

  • May combine two claims.

    Interpretationown data

    Both the algorithm design and the hardware noise affect the in-constraint probability.

    “Both the algorithm design and the hardware noise affect the in-constraint probability.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S4 (based).

    Premisenone given

    The initial state used by QAOA or L-VQE requires no two-qubit gates to prepare.

    “This is in sharp contrast with the initial state used by QAOA or L-VQE, which requires no two-qubit gates to prepare.”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim. May combine two claims.

    Premisenone given

    QAOA and L-VQE can tackle constrained-optimization problems in which the constraint is enforced by a penalty term, but their output is not guaranteed to satisfy the constraint.

    “While QAOA and L-VQE can tackle constrained-optimization problems in which the constraint is enforced by a penalty term, the output of these algorithms is not guaranteed to satisfy the constraint.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationreasoning

    Improved hardware fidelity would lead to more accurate initial state preparation and higher overall in-constraint probability.

    “Improved hardware fidelity would lead to more accurate initial state preparation and higher overall in-constraint probability.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationreasoning

    The running time of the algorithm scales inversely proportionally to the in-constraint probability due to the need to obtain at least one in-constraint sample.

    “In practice, the running time of the algorithm scales inversely proportionally to the in-constraint probability due to the need to obtain at least one in-constraint sample.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationreasoning

    XY-QAOA leads to an in-constraint probability of one and a high approximation ratio, if no noise is present.

    “This leads to an in-constraint probability of one and a high approximation ratio, if no noise is present.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Premisecitation

    The extractive summarization formulation that maximizes centrality and minimizes redundancy under a fixed summary length constraint has been proposed by R. McDonald and shown to be NP-hard to solve exactly.

    “This formulation of ES has been proposed by R. McDonald and shown to be -hard to solve exactly19.”
    Quote in the paperSubstantial claim0 of 1 sources checked
    • cites [19] McDonald, R. A study of global inference algorithms in multi-document summarization. In Advances in Information Retrieval, ECIR’07 557–564 (Springer, Berlin, 2007). https://doi.org/10.5555/1763653.1763720. source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Premisecitation

    There have been very large-scale demonstrations of QAOA on analog quantum simulators.

    “Lastly, there have been very large-scale demonstrations of QAOA on analog quantum simulators.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [64] Pagano, G. et al. Quantum approximate optimization of the long-range ising model with a trapped-ion quantum simulator. Proc. Natl. Acad. Sci 117, 25396–25401. https://doi.org/10.1073/pnas.2006373117 (2020). source

      Not checked in the free run.

    • cites [15] Ebadi, S. et al. Quantum optimization of maximum independent set using rydberg atom arrays. Science 376, 1209–1215. https://doi.org/10.1126/science.abo6587 (2022). source

      Not checked in the free run.

  • Probably not a substantial claim: may not pass S2 (checkable). May combine two claims.

    Interpretationown data

    Our results demonstrate how algorithmic and hardware progress are bringing the prospect of quantum advantage in constrained optimization closer, which can be leveraged in many industries including finance.

    “Our results demonstrate how algorithmic and hardware progress are bringing the prospect of quantum advantage in constrained optimization closer, which can be leveraged in many industries including finance65,66.”
    Quote in the paperNot a substantial claim0 of 2 sources checked
    • cites [65] Herman, D. et al. A survey of quantum computing for finance. https://doi.org/10.48550/ARXIV.2201.02773 (2022). source

      Not checked in the free run.

    • cites [66] Pistoia, M. et al. Quantum machine learning for finance iccad special session paper. In 2021 IEEE/ACM International Conference On Computer Aided Design (ICCAD), 1–9. https://doi.org/10.1109/ICCAD51958.2021.9643469 (2021). source

      Not checked in the free run.

  • Classified as probably not a substantial claim.

    Interpretationreasoning

    Execution of complex circuits for constrained optimization benefits from the underlying hardware's all-to-all connectivity, as the circuit depth would increase significantly if the circuit had to be compiled to a nearest-neighbor architecture.

    “Our execution of complex circuits for constrained optimization benefits from the underlying hardware’s all-to-all connectivity, as the circuit depth would increase significantly if the circuit had to be compiled to a nearest-neighbor architecture.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S2 (checkable), S3 (load-bearing). May combine two claims.

    Interpretationnone given

    Further advances are needed to reduce the hardware requirements of implementing such circuits and improve the fidelities of the hardware.

    “At the same time, we show that further advances are needed to reduce the hardware requirements of implementing such circuits and improve the fidelities of the hardware.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing). May combine two claims.

    Interpretationreasoning

    Since analog devices do not implement universal gate sets, their results are not directly comparable to ours.

    “However, since these analog devices do not implement universal gate sets, the results are not directly comparable to ours.”
    Quote in the paperNot a substantial claim
  • May combine two claims.

    Interpretationcitation

    Other hardware demonstrations of QAOA using alternative mixers to the transverse field were either not applied to hard-constrained problems or did not use an in-constraint initial state.

    “While there have been other hardware demonstrations of QAOA using alternative mixers to the transverse field, they were either not applied to hard-constrained problems or did not use an in-constraint initial state.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationnone given

    To the authors' knowledge, there has only been one other demonstration of QAOA with constrained mixers and Dicke-state initialization on quantum hardware.

    “To the authors’ knowledge, there has only be one other demonstration of QAOA with constrained mixers and Dicke-state initialization on quantum hardware.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Interpretationnone given

    One potential solution to the challenge of choosing parameters is using a circuit that is sufficiently expressive to solve the problem exactly, such as the circuit used in L-VQE.

    “One potential solution to this challenge is using a circuit that is sufficiently expressive to solve the problem exactly, such as the circuit used in L-VQE.”
    Quote in the paperNot a substantial claim
  • Classified as probably not a substantial claim. May combine two claims.

    Study design and conductnone given

    The results presented here were obtained with no error mitigation, which is not the case for many previous demonstrations.

    “The results we present here were obtained with no error mitigation, which is not the case for many of the previous demonstrations.”
    Quote in the paperSubstantial claim
  • May combine two claims.

    Interpretationreasoning

    The trade-off between in-constraint probability and approximation ratio is an important weakness of unconstrained quantum algorithms applied to constrained problems, necessitating the development and implementation of quantum algorithms that natively preserve constraints.

    “This trade-off is an important weakness of unconstrained quantum algorithms applied to constrained problems, necessitating the development and implementation of quantum algorithms that natively preserve constraints.”
    Quote in the paperSubstantial claim
  • Probably not a substantial claim: may not pass S4 (based).

    Interpretationnone given

    The trade-off behavior between in-constraint probability and approximation ratio applies to all unconstrained quantum algorithms that are not expressive enough to solve the problem exactly.

    “This trade-off behavior is not specific to QAOA and indeed applies to all unconstrained quantum algorithms that are not expressive enough to solve the problem exactly.”
    Quote in the paperNot a substantial claim
  • Probably not a substantial claim: may not pass S3 (load-bearing).

    Study design and conductown data

    Only three 14-qubit and three 20-qubit XY-QAOA instances were solved on H1-1 due to high circuit depth and correspondingly high running time on trapped-ion hardware.

    “All the statistics we report are computed over 10 problem instances for each number of qubits, with the exception of XY-QAOA on H1-1 where only three 14-qubit and three 20-qubit instances are solved due to the high circuit depth and correspondingly high running time on trapped-ion hardware.”
    Quote in the paperNot a substantial claim
25 of 25
  • The paper relies on this without support.

    The CNN/DailyMail articles used to generate the optimization instances are representative of practical extractive summarization problems.

    “To generate the optimization problems to be solved, we use articles from the CNN/DailyMail dataset36.”
  • The paper relies on this without support.

    The survey of previous quantum optimization demonstrations in Table 2 is complete enough to establish that this work is the largest demonstration to date.

    “In this work, we show the largest demonstration to date of constrained optimization on a gate-based quantum computer.”
    “To the authors’ knowledge, there has only be one other demonstration of QAOA with constrained mixers and Dicke-state initialization on quantum hardware.”
  • The paper relies on this without support.

    The approximation ratio of random guess is a meaningful baseline for evaluating solution quality.

    “the thin dotted line marks the approximation ratio of a random solution”
    “provides results that are significantly better than random guess”
3 of 3

Claims other papers make about this one

Each is checked against this paper’s own text: does it say what the citing paper says it does?

  • The number of two-qubit gates is ≈10^3 at N = 18, putting our experiments among the largest quantum optimization demonstrations on quantum hardware to date.

    “We remark that the number of two-qubit gates is ≈103 at N = 18, putting our experiments among the largest quantum optimization demonstrations on quantum hardware to date (36–38).”
  • The high-round and large-problem-size QAOA circuits evaluated in this paper are the largest QAOA experimental implementations yet presented with respect to gate counts and depths of the circuits that the authors are aware of.

    “however the high round and large problem size QAOA circuits evaluated in this paper are the largest QAOA experimental implementations yet presented with respect to gate counts and depths of the circuits that the authors are aware of.”

    From High-Round QAOA for MAX $k$-SAT on Trapped Ion NISQ Devices (2023) · cites this paper as [38]

Cites

Flagged first, then by citations

Research works printed but not linked: 4

  1. Filippova, K., Surdeanu, M., Ciaramita, M. & Zaragoza, H. Company-oriented extractive summarization of financial news. In Proceedings of the 12th Conference of the European Chapter of the ACL (EACL 2009), 246–254. (Association for Computational Linguistics, Athens, Greece, 2009) https://doi.org/10.5555/1609067.1609094. · DOI
  2. McDonald, R. A study of global inference algorithms in multi-document summarization. In Advances in Information Retrieval, ECIR’07 557–564 (Springer, Berlin, 2007). https://doi.org/10.5555/1763653.1763720. · DOI
  3. Golden, J., Bärtschi, A., O’Malley, D. & Eidenbenz, S. QAOA-based fair sampling on NISQ devices. https://doi.org/10.48550/ARXIV.2101.03258 (2021). · DOI
  4. Lin, C.-Y. ROUGE: A package for automatic evaluation of summaries. In Text Summarization Branches Out 74–81 (Association for Computational Linguistics, 2004).

Cited by

Sorted by citations

Authors
Niroula, P., Shaydulin, R., Yalovetzky, R., Minssen, P., Herman, D., Hu, S., & Pistoia, M.
Affiliations
JPMorgan Chase & Co (United States) (US)
Corresponding author
Shaydulin, Ruslan
Venue
Scientific Reports
Published
2022-10-13
Volume
12
Issue
1
Pages
17171-17171
ISSN
2045-2322 (ISSN-L)
OpenAlex
W4304893331
Cited by
59
References
74
Citations by year
2026: 9 · 2025: 12 · 2024: 15 · 2023: 21 · 2022: 2
FWCI
4.12
Type
journal article
Language
en
Open access
Locations
  • Scientific Reports (publishedVersion, cc-by)
  • PubMed Central (publishedVersion, cc-by)
  • PubMed (publishedVersion)
  • arXiv (Cornell University) (submittedVersion)
  • DOAJ (DOAJ: Directory of Open Access Journals) (submittedVersion, cc-by-sa)
  • OSTI OAI (U.S. Department of Energy Office of Scientific and Technical Information) (submittedVersion)
  • arXiv (Cornell University) (cc-by)
Funders
  • U.S. Department of Energy (DE-SC0020312)
  • National Science Foundation
  • Air Force Office of Scientific Research
  • Defense Advanced Research Projects Agency
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
extractive summarization, trapped-ion quantum computer, Quantum Alternating Operator Ansatz, quantum approximate optimization algorithm, constraint encoding, quantum advantage, natural language processing

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