SparQSim: Simulating Scalable Quantum Algorithms via Sparse Quantum State Representations
Pith reviewed 2026-05-22 22:57 UTC · model grok-4.3
The pith
SparQSim stores only nonzero quantum state components to simulate large algorithms faster and with less memory than full-state methods when sparsity holds.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
By storing only the nonzero components of the quantum state at the register level, SparQSim enables flexible simulation of both elementary gates and integrated QRAM operations. Benchmarks drawn from QASMBench and MQTBench show lower execution time and memory use than Schrödinger-based simulators on high-sparsity circuits. Full end-to-end simulations of quantum linear system solvers that rely on a discrete adiabatic method return results consistent with theoretical predictions.
What carries the argument
The sparse quantum state representation that records only nonzero amplitudes and applies operations directly to those entries.
If this is right
- High-sparsity circuits finish in less time than they do under full-state Schrödinger simulation.
- Memory consumption drops below that of conventional simulators for the same sparse circuits.
- Quantum linear system solvers based on the discrete adiabatic method can be simulated end-to-end and still agree with theory.
- QRAM and oracle operations become directly usable inside the same sparse framework.
Where Pith is reading between the lines
- The same sparse bookkeeping could let researchers test larger instances of other algorithms whose states remain sparse for most of the computation.
- Algorithm designers could iterate on oracle-based routines by running full simulations on classical machines before moving to hardware.
- Extensions that automatically detect and exploit sparsity in new circuit families would widen the set of algorithms that become classically testable.
Load-bearing premise
The quantum states produced by the target algorithms stay sparse enough that the cost of tracking the nonzero entries stays smaller than the savings from not storing the full state vector.
What would settle it
Run a high-sparsity circuit from the benchmarks on both SparQSim and a standard Schrödinger simulator and observe whether SparQSim ever uses more wall-clock time or more memory, or run the linear-system-solver simulation and check whether its output deviates from the theoretical prediction.
Figures
read the original abstract
Efficient simulation of large-scale quantum algorithms is pivotal yet challenging due to the exponential growth of the state space inherent in both Sch\"odinger-based and Feynman-based methods. While Feynman-based simulators can be highly efficient when the quantum state is sparse, these simulators often do not fully support the simulation of large-scale, complex quantum algorithms which rely on QRAM and other oracle-based operations. In this work, we present SparQSim, a quantum simulator implemented in C++ and inspired by the Feynman-based method. SparQSim operates at the register level by storing only the nonzero components of the quantum state, enabling flexible and resource-efficient simulation of basic quantum operations and integrated QRAM for advanced applications such as quantum linear system solvers. In particular, numerical experiments on benchmarks from QASMBench and MQTBench demonstrate that SparQSim outperforms conventional Schr\"odinger-based simulators in both execution time and memory usage for circuits with high sparsity. Moreover, full-process simulations of quantum linear system solvers based on a discrete adiabatic method yield results that are consistent with theoretical predictions. This work establishes SparQSim as a promising platform for the efficient simulation of scalable quantum algorithms.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper introduces SparQSim, a C++ simulator inspired by Feynman methods that stores only nonzero state components at the register level and integrates QRAM support. It claims that this yields better execution time and memory usage than conventional Schrödinger simulators on high-sparsity circuits from QASMBench and MQTBench, and that full simulations of discrete-adiabatic quantum linear system solvers produce results consistent with theoretical predictions.
Significance. If the sparsity-maintenance claim is substantiated with quantitative data, the work could offer a practical middle ground between dense state-vector simulators and path-integral methods for algorithms that preserve sparsity, particularly those involving oracles.
major comments (1)
- [Abstract / Numerical Experiments section] The central performance claim (outperformance on QASMBench/MQTBench and QLSS simulations) rests on the unverified assumption that the encountered states remain sufficiently sparse for the nonzero-component data structure to beat dense simulation in both time and memory. No trace of nonzero count, growth rate, or peak density relative to 2^n is reported, so it is impossible to confirm that management overhead does not negate the advertised gains.
Simulated Author's Rebuttal
We thank the referee for highlighting the need to substantiate the sparsity assumption underlying our performance claims. We address this comment directly below.
read point-by-point responses
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Referee: [Abstract / Numerical Experiments section] The central performance claim (outperformance on QASMBench/MQTBench and QLSS simulations) rests on the unverified assumption that the encountered states remain sufficiently sparse for the nonzero-component data structure to beat dense simulation in both time and memory. No trace of nonzero count, growth rate, or peak density relative to 2^n is reported, so it is impossible to confirm that management overhead does not negate the advertised gains.
Authors: We agree that explicit reporting of sparsity metrics is necessary to fully substantiate the claims. The current manuscript states that the benchmarks are chosen for their high sparsity but does not quantify the number of nonzero amplitudes, their growth, or the peak density relative to 2^n. In the revised manuscript we will add a dedicated subsection (or supplementary figures) in the Numerical Experiments section that reports, for each benchmark circuit and the QLSS simulations: (i) the peak number of nonzero state components, (ii) the evolution of nonzero count over gate applications, and (iii) the sparsity ratio (nonzeros / 2^n) at key points. These data will allow direct verification that the sparse representation remains advantageous and that overhead does not dominate. revision: yes
Circularity Check
No significant circularity; results rest on implementation and benchmarks
full rationale
The paper describes an implementation of a sparse-state quantum simulator (SparQSim) and reports its performance via direct numerical experiments on QASMBench/MQTBench circuits and discrete-adiabatic QLSS simulations. No equations, derivations, or predictions are presented that reduce by construction to fitted inputs, self-definitions, or self-citation chains. Performance claims are grounded in measured execution time and memory comparisons against Schrödinger simulators, with consistency to external theoretical predictions for the QLSS case. The method relies on standard sparse data structures and QRAM integration without invoking uniqueness theorems or ansatzes from prior author work as load-bearing justification.
Axiom & Free-Parameter Ledger
axioms (1)
- standard math Standard postulates of quantum mechanics govern state evolution under unitary operations and measurements
Reference graph
Works this paper leans on
-
[1]
Non-interference operations Non-interference operations are those that act on each computational branch independently, meaning that each branch is processed without interacting the others. Specifically, these operations involve either phase modifi- cation on certain branches or bit flips on specific qubits. Non-interference opera�on Amplitude modifica�on R...
-
[2]
Such operations of- ten result in the creation of new branches or the elim- ination of existing ones
Interference operations Interference operations, related to quantum interfer- ence, combine coherent branches by either amplifying or diminishing their amplitudes. Such operations of- ten result in the creation of new branches or the elim- ination of existing ones. For example, a Hadamard gate transforms the basis state |0⟩ into the superposi- tion |+⟩ = ...
-
[3]
3, the target qubit is highlighted in red
As illustrated in Fig. 3, the target qubit is highlighted in red. The elements of the execution list are either oper- ated on individually or coherently, which may lead to new branches or the amplification or diminishment of existing branches. After computation, some branches may acquire zero 5 Interference opera�on To be cleared Sort by register values E...
-
[4]
Multi-threading with OpenMP SparQSim is designed to support multi-threading with OpenMP. In the case of non-interference operations, the branches of the state remain independent throughout the simulation. This independence allows parallelism to be achieved by dividing the branches into several chunks and assigning each chunk to a different thread. Each th...
-
[5]
The higher the sparsity, the more efficient the algorithm becomes
Performance of quantum operations on different sparsity levels As a quantum circuit simulator inspired by the Feynman-based simulation, SparQSim benefits from varying levels of state sparsity. The higher the sparsity, the more efficient the algorithm becomes. In this sec- tion, we compare the performance of SparQSim across different sparsity levels on ini...
-
[6]
Performance of speed-up by multi-threading In this section, we evaluate the performance improve- ment achieved through parallelization using OpenMP. Since interference and non-interference operations adopt different strategies and exhibit distinct time scaling pat- terns (as shown in Fig. 4), our tests of parallelization are conducted separately for these...
-
[7]
Performance of benchmarks to other different simulators In this part, we evaluate the performance of SparQSim by comparing it with several widely used quantum sim- ulators, including Qiskit, Qsim, and GraFeyn. To as- sess SparQSim’s efficiency, particularly in cases where quantum circuits exhibit significant sparsity, we conduct benchmarks across various ...
-
[8]
The constant θ is independent of the total time T but depends on the condition number κ
The performance of the QLSS algorithm The discrete adiabatic theorem states that the error between the discrete evolution U(s) and its ideal evolu- tion UA(s) is bounded by the expression: ϵ = ∥U(s) |ψ0⟩ − UA(s) |ψ0⟩ ∥ ≤ θ T , (7) where ∥·∥ denotes the spectral norm and |ψ0⟩ is the initial ground state. The constant θ is independent of the total time T bu...
-
[9]
A. W. Harrow, A. Hassidim, and S. Lloyd, Quantum al- gorithm for linear systems of equations, Phys. Rev. Lett. 103, 150502 (2009). 10 (a) (b) (c) (d) (e) (f) FIG. 6. Error Between Quantum State from Adiabatic Quantum Walks and Ideal State Versus1/T for Different Linear Equations. The error, defined as in Eq. 7, is presented for different matrix forms (pos...
work page 2009
-
[10]
P. C. Costa, D. An, Y. R. Sanders, Y. Su, R. Bab- bush, and D. W. Berry, Optimal scaling quantum linear- systems solver via discrete adiabatic theorem, PRX Quantum 3, 040303 (2022)
work page 2022
-
[11]
P. Rebentrost, M. Mohseni, and S. Lloyd, Quantum sup- port vector machine for big data classification, Phys. Rev. Lett. 113, 130503 (2014). 11
work page 2014
-
[12]
J. Biamonte, P. Wittek, N. Pancotti, P. Rebentrost, N. Wiebe, and S. Lloyd, Quantum machine learning, Na- ture 549, 195 (2017)
work page 2017
-
[13]
M. Schuld and N. Killoran, Quantum machine learning in feature hilbert spaces, Phys. Rev. Lett. 122, 040504 (2019)
work page 2019
-
[14]
C. H. Bennett and G. Brassard, Quantum cryptogra- phy: Public key distribution and coin tossing, Theoreti- cal computer science 560, 7 (2014)
work page 2014
- [15]
-
[16]
Y. Kim, A. Eddins, S. Anand, K. X. Wei, E. Van Den Berg, S. Rosenblatt, H. Nayfeh, Y. Wu, M. Zale- tel, K. Temme, et al. , Evidence for the utility of quan- tum computing before fault tolerance, Nature 618, 500 (2023)
work page 2023
-
[17]
Y.-H. Deng, Y.-C. Gu, H.-L. Liu, S.-Q. Gong, H. Su, Z.- J. Zhang, H.-Y. Tang, M.-H. Jia, J.-M. Xu, M.-C. Chen, J. Qin, L.-C. Peng, J. Yan, Y. Hu, J. Huang, H. Li, Y. Li, Y. Chen, X. Jiang, L. Gan, G. Yang, L. You, L. Li, H.- S. Zhong, H. Wang, N.-L. Liu, J. J. Renema, C.-Y. Lu, and J.-W. Pan, Gaussian boson sampling with pseudo- photon-number-resolving de...
work page 2023
-
[18]
Preskill, Quantum computing in the nisq era and be- yond, Quantum 2, 79 (2018)
J. Preskill, Quantum computing in the nisq era and be- yond, Quantum 2, 79 (2018)
work page 2018
- [19]
- [20]
- [21]
-
[22]
Complexity-Theoretic Foundations of Quantum Supremacy Experiments
S. Aaronson and L. Chen, Complexity-theoretic founda- tions of quantum supremacy experiments, arXiv preprint arXiv:1612.05903 (2016)
work page internal anchor Pith review Pith/arXiv arXiv 2016
-
[23]
L. Burgholzer, H. Bauer, and R. Wille, Hybrid schr¨ odinger-feynman simulation of quantum circuits with decision diagrams, in 2021 IEEE International Confer- ence on Quantum Computing and Engineering (QCE) (2021) pp. 199–206
work page 2021
-
[24]
S. Westrick, P. Liu, B. Kang, C. McDonald, M. Rainey, M. Xu, J. Arora, Y. Ding, and U. A. Acar, Grafeyn: Efficient parallel sparse simulation of quantum circuits, in Proceedings of the IEEE International Conference on Quantum Computing and Engineering (2024)
work page 2024
-
[25]
qHiPSTER: The Quantum High Performance Software Testing Environment
M. Smelyanskiy, N. P. Sawaya, and A. Aspuru-Guzik, qhipster: The quantum high performance software testing environment, arXiv preprint arXiv:1601.07195 (2016)
work page internal anchor Pith review Pith/arXiv arXiv 2016
-
[26]
T. H¨ aner and D. S. Steiger, 5 petabyte simulation of a 45- qubit quantum circuit, inProceedings of the International Conference for High Performance Computing, Network- ing, Storage and Analysis (2017) pp. 1–10
work page 2017
-
[27]
E. Pednault, J. A. Gunnels, G. Nannicini, L. Horesh, and R. Wisnieff, Leveraging secondary storage to sim- ulate deep 54-qubit sycamore circuits, arXiv preprint arXiv:1910.09534 (2019)
-
[28]
A. Zulehner and R. Wille, Advanced simulation of quan- tum computations, IEEE Transactions on Computer- Aided Design of Integrated Circuits and Systems 38, 848 (2019)
work page 2019
-
[29]
I. L. Markov, A. Fatima, S. V. Isakov, and S. Boixo, Massively parallel approximate simulation of hard quan- tum circuits, in 2020 57th ACM/IEEE Design Automa- tion Conference (DAC) (IEEE, 2020) pp. 1–6
work page 2020
-
[30]
B. Villalonga, D. Lyakh, S. Boixo, H. Neven, T. S. Hum- ble, R. Biswas, E. G. Rieffel, A. Ho, and S. Mandr` a, Establishing the quantum supremacy frontier with a 281 pflop/s simulation, Quantum Science and Technology 5, 034003 (2020)
work page 2020
-
[31]
A. Fatima and I. L. Markov, Faster schr¨ odinger-style sim- ulation of quantum circuits, in 2021 IEEE International Symposium on High-Performance Computer Architecture (HPCA) (2021) pp. 194–207
work page 2021
-
[32]
Y. Suzuki, Y. Kawase, Y. Masumura, Y. Hiraga, M. Nakadai, J. Chen, K. M. Nakanishi, K. Mitarai, R. Imai, S. Tamiya, T. Yamamoto, T. Yan, T. Kawakubo, Y. O. Nakagawa, Y. Ibe, Y. Zhang, H. Yamashita, H. Yoshimura, A. Hayashi, and K. Fujii, Qulacs: a fast and versatile quantum circuit simulator for research pur- pose, Quantum 5, 559 (2021)
work page 2021
-
[33]
C. Zhang, Z. Song, H. Wang, K. Rong, and J. Zhai, Hyquas: hybrid partitioner based quantum circuit simu- lation system on gpu, in Proceedings of the 35th ACM International Conference on Supercomputing , ICS ’21 (Association for Computing Machinery, New York, NY, USA, 2021) pp. 443–454
work page 2021
-
[34]
S. Jaques and T. H¨ aner, Leveraging state sparsity for more efficient quantum simulations, ACM Transactions on Quantum Computing 3, 10.1145/3491248 (2022)
-
[35]
V. Giovannetti, S. Lloyd, and L. Maccone, Quantum ran- dom access memory, Physical review letters 100, 160501 (2008)
work page 2008
-
[36]
V. Giovannetti, S. Lloyd, and L. Maccone, Architectures for a quantum random access memory, Physical Review A 78, 052310 (2008)
work page 2008
-
[37]
C. T. Hann, A. Gyenis, T. Lanting, K. Zhu, L. B. Ioffe, G. Burkard, J. M. Martinis, and C. Neill, Resilience of quantum random access memory to generic noise, PRX Quantum 2, 020311 (2021)
work page 2021
-
[38]
H.-S. Li, D. Ding, Z.-M. Li, L.-L. Zhu, and S.-P. Liu, Effi- cient quantum arithmetic operation circuits for quantum image processing, Science China Physics, Mechanics & Astronomy 63, 1 (2020)
work page 2020
-
[39]
Optimizing Quantum Circuits for Arithmetic
T. H¨ aner, M. Roetteler, and K. M. Svore, Optimiz- ing quantum circuits for arithmetic, arXiv preprint arXiv:1805.12445 (2018)
work page internal anchor Pith review Pith/arXiv arXiv 2018
-
[40]
K. Mitarai, M. Kitagawa, and K. Fujii, Quantum analog- digital conversion, Phys. Rev. A 99, 012301 (2019)
work page 2019
-
[41]
E. Mu˜ noz-Coreas and H. Thapliyal, T-count and qubit optimized quantum circuit design of the non-restoring square root algorithm, ACM Journal on Emerging Tech- nologies in Computing Systems (JETC) 14, 1 (2018)
work page 2018
-
[42]
A. M. Childs, R. Kothari, and R. D. Somma, Quantum algorithm for systems of linear equations with exponen- tially improved dependence on precision, SIAM Journal on Computing 46, 1920 (2017)
work page 1920
-
[43]
Y. b. u. Suba¸ s ı, R. D. Somma, and D. Orsucci, Quan- tum algorithms for systems of linear equations inspired by adiabatic quantum computing, Phys. Rev. Lett. 122, 060504 (2019). 12
work page 2019
-
[44]
A. Li, S. Stein, S. Krishnamoorthy, and J. Ang, Qasm- bench: A low-level quantum benchmark suite for nisq evaluation and simulation, ACM Transactions on Quan- tum Computing 4, 10.1145/3550488 (2023)
-
[45]
N. Quetschlich, L. Burgholzer, and R. Wille, MQT Bench: Benchmarking Software and Design Automation Tools for Quantum Computing, Quantum7, 1062 (2023)
work page 2023
-
[46]
A. M. Dalzell, B. D. Clader, G. Salton, M. Berta, C. Y.- Y. Lin, D. A. Bader, N. Stamatopoulos, M. J. A. Schuetz, F. G. S. L. Brand˜ ao, H. G. Katzgraber, and W. J. Zeng, End-to-end resource analysis for quantum interior-point methods and portfolio optimization, PRX Quantum 4, 040325 (2023)
work page 2023
-
[47]
A. W. Cross, L. S. Bishop, J. A. Smolin, and J. M. Gambetta, Open quantum assembly language (2017), arXiv:1707.03429 [quant-ph]
work page internal anchor Pith review Pith/arXiv arXiv 2017
-
[48]
D. W. Berry, High-order quantum algorithm for solving linear differential equations, Journal of Physics A: Math- ematical and Theoretical 47, 105301 (2014)
work page 2014
-
[49]
D. W. Berry, A. M. Childs, A. Ostrander, and G. Wang, Quantum algorithm for linear differential equations with exponentially improved dependence on precision, Com- munications in Mathematical Physics 356, 1057 (2017)
work page 2017
- [50]
-
[51]
A. Ambainis, Variable time amplitude amplification and quantum algorithms for linear algebra problems, in STACS’12 (29th Symposium on Theoretical Aspects of Computer Science), Vol. 14 (LIPIcs, 2012) pp. 636–647
work page 2012
- [52]
- [53]
-
[54]
Aaronson, Read the fine print, Nature Physics 11, 291 (2015)
S. Aaronson, Read the fine print, Nature Physics 11, 291 (2015)
work page 2015
-
[55]
B. D. Clader, A. M. Dalzell, N. Stamatopoulos, G. Salton, M. Berta, and W. J. Zeng, Quantum resources required to block-encode a matrix of classical data, IEEE Transactions on Quantum Engineering 3, 1 (2022)
work page 2022
-
[56]
P. Costa, D. An, R. Babbush, and D. Berry, The dis- crete adiabatic quantum linear system solver has lower constant factors than the randomized adiabatic solver, arXiv preprint arXiv:2312.07690 (2023)
-
[57]
R. LaRose, A brief history of quantum vs classical com- putational advantage, arXiv preprint arXiv:2412.14703 (2024). 1 Supplementary Information SparQSim: Simulating Scalable Quantum Algorithms via Sparse Quantum State Representations I. DATA STRUCTURE OF SPARQSIM Here is the list of properties and methods of class System and class StateStorage: TABLE S1...
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