Minimizing entanglement entropy for enhanced quantum state preparation
Pith reviewed 2026-05-19 02:54 UTC · model grok-4.3
The pith
Minimizing entanglement entropy of a target quantum state enables more accurate preparation using matrix product states on near-term devices.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
The paper establishes that transforming a target quantum state to one with minimized entanglement entropy and then preparing it via a matrix product state representation achieves high accuracy preparation, with accuracy lower bounds directly related to the entanglement entropy of the transformed state. This two-step process addresses the challenge of preparing arbitrary states that would otherwise require an exponential number of two-qubit gates.
What carries the argument
The entanglement entropy minimization step that transforms the target state into a lower-entanglement version suitable for efficient matrix product state representation.
Load-bearing premise
A target quantum state can be transformed into one with reduced entanglement entropy while still allowing high-accuracy recovery of the original state through matrix product state preparation.
What would settle it
A calculation showing that for some target states the accuracy bound from the entanglement entropy is too loose to achieve the claimed high accuracy, or an experiment where the prepared state deviates significantly from the target despite low entropy.
Figures
read the original abstract
Quantum state preparation is an important subroutine in many quantum algorithms. The goal is to encode classical information directly to the quantum state so that it is possible to leverage quantum algorithms for data processing. However, quantum state preparation of arbitrary states scales exponentially in the number of two-qubit gates, and this makes quantum state preparation a very difficult task on quantum computers, especially on near-term noisy devices. This represents a major challenge in achieving quantum advantage. We present and analyze a novel two-step state preparation method where we first minimize the entanglement entropy of the target quantum state, thus transforming the state to one that is easier to prepare. The state with reduced entanglement entropy is then represented as a matrix product state, resulting in a high accuracy preparation of the target state. Our method is suitable for NISQ devices and we give rigorous lower bounds on the accuracy of the prepared state in terms of the entanglement entropy. We benchmark our method with 2D normal distribution and Ricker wavelet states with 6--20 qubits.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript proposes a two-step quantum state preparation protocol for NISQ devices. First, a transformation is applied to the target state |ψ⟩ to produce |φ⟩ = T|ψ⟩ with minimized entanglement entropy S(φ). The low-entropy state is then approximated by a matrix product state |φ_MPS⟩, after which the inverse transformation is applied to recover an approximation to the original state. The authors assert that this yields high-accuracy preparation and provide rigorous lower bounds on the final fidelity expressed in terms of the reduced entanglement entropy. Benchmarks are reported for 2D normal-distribution and Ricker-wavelet target states on 6–20 qubits.
Significance. If the accuracy bounds are shown to be rigorous and to account for all error sources, the approach could meaningfully reduce the resource cost of state preparation by exploiting entanglement minimization before MPS truncation. The explicit benchmarks on concrete states and the claim of NISQ suitability constitute a practical contribution, though the method’s advantage over direct MPS preparation of the original state remains to be quantified.
major comments (1)
- [Section on rigorous lower bounds] § on rigorous lower bounds (abstract and main text): The claimed lower bounds on prepared-state accuracy are stated solely in terms of the reduced entanglement entropy S(φ). It is unclear whether these bounds incorporate the MPS truncation error after the approximation of |φ⟩ or the error amplification that occurs when the inverse map T† is applied to the truncated |φ_MPS⟩. If the derivation treats the MPS step as exact or assumes T is exactly invertible without error propagation analysis, the guarantee for fidelity to the original |ψ⟩ does not follow. A concrete error-propagation lemma or numerical bound that includes both sources of error is required for the central claim.
minor comments (2)
- [Abstract] The abstract and introduction would benefit from an explicit statement of the fidelity metric (e.g., 1−|⟨ψ|ψ_prep⟩|) and the precise definition of the transformation T used to minimize entanglement entropy.
- [Benchmark section] Figure captions for the benchmark results should include the bond dimension chosen for the MPS representation and the resulting truncation error for each qubit number.
Simulated Author's Rebuttal
We thank the referee for their careful reading and constructive feedback. We address the single major comment below and will revise the manuscript accordingly to strengthen the rigor of our error bounds.
read point-by-point responses
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Referee: [Section on rigorous lower bounds] § on rigorous lower bounds (abstract and main text): The claimed lower bounds on prepared-state accuracy are stated solely in terms of the reduced entanglement entropy S(φ). It is unclear whether these bounds incorporate the MPS truncation error after the approximation of |φ⟩ or the error amplification that occurs when the inverse map T† is applied to the truncated |φ_MPS⟩. If the derivation treats the MPS step as exact or assumes T is exactly invertible without error propagation analysis, the guarantee for fidelity to the original |ψ⟩ does not follow. A concrete error-propagation lemma or numerical bound that includes both sources of error is required for the central claim.
Authors: We agree that the presentation of the bounds requires clarification to be fully rigorous. The current derivation provides a lower bound on fidelity expressed in terms of the reduced entanglement entropy S(φ) after the transformation, treating the subsequent MPS step as achieving a controllable approximation error that is separately bounded by the bond dimension. However, the explicit propagation of this truncation error through the inverse map T† and any potential amplification was not stated as a separate lemma. In the revised manuscript we will add a concise error-propagation result (new Lemma in Section III) that combines both contributions: the total infidelity is bounded by a term linear in S(φ) plus the MPS truncation error scaled by the operator norm of T. We will also include a short numerical check confirming that the composite bound remains tight for the reported 2D-normal and Ricker-wavelet examples. This addition directly addresses the referee’s concern without altering the central claims. revision: yes
Circularity Check
No significant circularity; derivation relies on standard quantum information quantities
full rationale
The paper describes a two-step procedure: transform the target state to minimize entanglement entropy S, represent the result as an MPS, then (implicitly) invert. The abstract and description state that rigorous lower bounds on prepared-state accuracy are given in terms of the (reduced) entanglement entropy. These bounds are presented as following from standard entanglement measures and MPS approximation properties rather than from any fitted parameter, self-referential definition, or self-citation chain that collapses the claim back onto the input data. No equations or steps are shown that equate a derived accuracy bound directly to a fitted quantity or to a prior result whose only justification is the present authors' own unverified ansatz. The method therefore remains self-contained against external benchmarks and does not reduce by construction to its inputs.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Quantum state preparation of arbitrary states scales exponentially in the number of two-qubit gates.
Reference graph
Works this paper leans on
-
[1]
P. W. Shor, Polynomial-time algorithms for prime factorization and discrete logarithms on a quantum computer, SIAM Journal on Computing 26, 1484 (1997)
work page 1997
-
[2]
L. K. Grover, A fast quantum mechanical algorithm for database search, in Proceedings of the Twenty-Eighth Annual ACM Symposium on Theory of Computing, STOC ’96 (Associ- ation for Computing Machinery, New York, NY , USA, 1996) p. 212–219
work page 1996
-
[3]
A. W. Harrow, A. Hassidim, and S. Lloyd, Quantum algorithm for linear systems of equations, Phys. Rev. Lett. 103, 150502 (2009)
work page 2009
-
[4]
V . V . Shende, S. S. Bullock, and I. L. Markov, Synthesis of quantum-logic circuits, IEEE Transactions on Computer-Aided Design of Integrated Circuits and Systems 25, 1000 (2006)
work page 2006
-
[5]
M. Plesch and ˇC. Brukner, Quantum-state preparation with uni- versal gate decompositions, Phys. Rev. A 83, 032302 (2011)
work page 2011
-
[6]
R. Iten, R. Colbeck, I. Kukuljan, J. Home, and M. Chris- tandl, Quantum circuits for isometries, Phys. Rev. A93, 032318 (2016)
work page 2016
-
[7]
M. E. Haque, M. Paul, A. Ulhaq, and T. Debnath, Advanced quantum image representation and compression using a dct- efrqi approach, Scientific Reports 13, 4129 (2023)
work page 2023
- [8]
-
[9]
N. Guseynov and N. Liu, Efficient explicit circuit for quantum state preparation of piece-wise continuous functions (2025), arXiv:2411.01131 [quant-ph]
-
[10]
J. Lemieux, M. Lostaglio, S. Pallister, W. Pol, K. Seetharam, S. Sim, and B. ¸ Sahino˘glu, Quantum sampling algorithms for quantum state preparation and matrix block-encoding (2024), arXiv:2405.11436 [quant-ph]
-
[11]
Creating superpositions that correspond to efficiently integrable probability distributions
L. Grover and T. Rudolph, Creating superpositions that corre- spond to efficiently integrable probability distributions (2002), arXiv:quant-ph/0208112 [quant-ph]
work page internal anchor Pith review Pith/arXiv arXiv 2002
-
[12]
M. Möttönen, V . J. J, V . Bergholm, and M. M. Salomaa, Trans- formation of quantum states using uniformly controlled rota- tions, Quantum Info. Comput. 5, 467 (2005)
work page 2005
-
[13]
I. F. Araujo, D. K. Park, F. Petruccione, and A. J. da Silva, A divide-and-conquer algorithm for quantum state preparation, Scientific Reports 11, 6329 (2021)
work page 2021
- [14]
-
[15]
A. G. Rattew, Y . Sun, P. Minssen, and M. Pistoia, The Effi- cient Preparation of Normal Distributions in Quantum Regis- ters, Quantum 5, 609 (2021)
work page 2021
-
[16]
M. T. West, A. C. Nakhl, J. Heredge, F. M. Creevey, L. C. L. Hollenberg, M. Sevior, and M. Usman, Drastic circuit depth re- ductions with preserved adversarial robustness by approximate encoding for quantum machine learning, Intelligent Computing 3, 0100 (2024)
work page 2024
- [17]
-
[18]
G. Marin-Sanchez, J. Gonzalez-Conde, and M. Sanz, Quantum algorithms for approximate function loading, Phys. Rev. Res.5, 033114 (2023)
work page 2023
-
[19]
M. Benedetti, E. Grant, L. Wossnig, and S. Severini, Adversar- ial quantum circuit learning for pure state approximation, New Journal of Physics 21, 043023 (2019)
work page 2019
-
[20]
J. Zylberman and F. Debbasch, Efficient quantum state prepa- ration with walsh series, Phys. Rev. A 109, 042401 (2024)
work page 2024
-
[21]
N. Gleinig and T. Hoefler, An efficient algorithm for sparse quantum state preparation (IEEE Press, 2022) p. 433
work page 2022
-
[22]
E. Malvetti, R. Iten, and R. Colbeck, Quantum Circuits for Sparse Isometries, Quantum 5, 412 (2021)
work page 2021
- [23]
-
[24]
I. Gaidai and R. Herrman, Decomposition of sparse ampli- tude permutation gates with application to preparation of sparse clustered quantum states (2025), arXiv:2504.08705 [quant-ph]
-
[25]
P. Yuan and S. Zhang, Depth-efficient quantum circuit synthesis for deterministic dicke state preparation (2025), arXiv:2505.15413 [quant-ph]
- [26]
-
[27]
A. Bärtschi and S. Eidenbenz, Deterministic preparation of dicke states, in Fundamentals of Computation Theory , edited by L. A. G ˛ asieniec, J. Jansson, and C. Levcopoulos (Springer International Publishing, Cham, 2019) pp. 126–139
work page 2019
-
[28]
F. Mozafari, M. Soeken, H. Riener, and G. De Micheli, Automatic uniform quantum state preparation using decision diagrams, in 2020 IEEE 50th International Symposium on Multiple-Valued Logic (ISMVL) (2020) pp. 170–175
work page 2020
-
[29]
F. Mozafari, H. Riener, M. Soeken, and G. De Micheli, Efficient boolean methods for preparing uniform quantum states, IEEE Transactions on Quantum Engineering 2, 1 (2021)
work page 2021
-
[30]
F. Mozafari, G. De Micheli, and Y . Yang, Efficient deterministic preparation of quantum states using decision diagrams, Phys. Rev. A 106, 022617 (2022)
work page 2022
-
[31]
I. F. Araujo, C. Blank, I. C. S. Araújo, and A. J. da Silva, Low-rank quantum state preparation, IEEE Transactions on 7 Computer-Aided Design of Integrated Circuits and Systems43, 161 (2024)
work page 2024
- [32]
- [33]
- [34]
-
[35]
K. Endo, T. Nakamura, K. Fujii, and N. Yamamoto, Quantum self-learning monte carlo and quantum-inspired fourier trans- form sampler, Phys. Rev. Res. 2, 043442 (2020)
work page 2020
-
[36]
Ran, Encoding of matrix product states into quantum circuits of one- and two-qubit gates, Phys
S. Ran, Encoding of matrix product states into quantum circuits of one- and two-qubit gates, Phys. Rev. A 101, 032310 (2020)
work page 2020
-
[37]
D. Malz, G. Styliaris, Z. Wei, and J. I. Cirac, Preparation of ma- trix product states with log-depth quantum circuits, Phys. Rev. Lett. 132, 040404 (2024)
work page 2024
-
[38]
M. S. Rudolph, J. Chen, J. Miller, A. Acharya, and A. Perdomo- Ortiz, Decomposition of matrix product states into shallow quantum circuits, Quantum Science and Technology 9, 015012 (2023)
work page 2023
-
[39]
M. Ben-Dov, D. Shnaiderov, A. Makmal, and E. G. D. Torre, Approximate encoding of quantum states using shallow cir- cuits, npj Quantum Information 10, 65 (2024)
work page 2024
-
[40]
A. A. Melnikov, A. A. Termanova, S. V . Dolgov, F. Neukart, and M. R. Perelshtein, Quantum state preparation using tensor networks, Quantum Science and Technology 8, 035027 (2023)
work page 2023
-
[41]
K. C. Smith, A. Khan, B. K. Clark, S. Girvin, and T.-C. Wei, Constant-depth preparation of matrix product states with adap- tive quantum circuits, PRX Quantum 5, 030344 (2024)
work page 2024
-
[42]
U. Schollwöck, The density-matrix renormalization group in the age of matrix product states, Annals of Physics 326, 96 (2011)
work page 2011
-
[43]
Vidal, Efficient classical simulation of slightly entangled quantum computations, Phys
G. Vidal, Efficient classical simulation of slightly entangled quantum computations, Phys. Rev. Lett. 91, 147902 (2003)
work page 2003
-
[44]
S. Fomichev, K. Hejazi, M. S. Zini, M. Kiser, J. Fraxanet, P. A. M. Casares, A. Delgado, J. Huh, A.-C. V oigt, J. E. Mueller, and J. M. Arrazola, Initial state preparation for quantum chem- istry on quantum computers, PRX Quantum 5, 040339 (2024)
work page 2024
-
[45]
A. Holmes and A. Y . Matsuura, Efficient quantum circuits for accurate state preparation of smooth, differentiable functions, in 2020 IEEE International Conference on Quantum Computing and Engineering (QCE) (2020) pp. 169–179
work page 2020
-
[46]
J. I. Cirac, D. Pérez-García, N. Schuch, and F. Verstraete, Ma- trix product states and projected entangled pair states: Con- cepts, symmetries, theorems, Rev. Mod. Phys. 93, 045003 (2021)
work page 2021
-
[47]
P.-F. Zhou, R. Hong, and S.-J. Ran, Automatically differentiable quantum circuit for many-qubit state preparation, Phys. Rev. A 104, 042601 (2021)
work page 2021
-
[48]
J. Gonzalez-Conde, T. W. Watts, P. Rodriguez-Grasa, and M. Sanz, Efficient quantum amplitude encoding of polynomial functions, Quantum 8, 1297 (2024)
work page 2024
-
[49]
P. Gundlapalli and J. Lee, Deterministic and entanglement- efficient preparation of amplitude-encoded quantum registers, Phys. Rev. Appl. 18, 024013 (2022)
work page 2022
-
[50]
S. R. White, Density matrix formulation for quantum renormal- ization groups, Phys. Rev. Lett. 69, 2863 (1992)
work page 1992
-
[51]
Vidal, Class of quantum many-body states that can be effi- ciently simulated, Phys
G. Vidal, Class of quantum many-body states that can be effi- ciently simulated, Phys. Rev. Lett. 101, 110501 (2008)
work page 2008
-
[52]
G. Evenbly and G. Vidal, Algorithms for entanglement renor- malization: Boundaries, impurities and interfaces, Journal of Statistical Physics 157, 931 (2014)
work page 2014
-
[53]
M. T. Fishman and S. R. White, Compression of correlation matrices and an efficient method for forming matrix product states of fermionic gaussian states, Phys. Rev. B 92, 075132 (2015)
work page 2015
-
[54]
J. Hauschild, E. Leviatan, J. H. Bardarson, E. Altman, M. P. Zaletel, and F. Pollmann, Finding purifications with minimal entanglement, Phys. Rev. B 98, 235163 (2018)
work page 2018
-
[55]
M. Schuld and N. Killoran, Quantum machine learning in fea- ture hilbert spaces, Phys. Rev. Lett. 122, 040504 (2019)
work page 2019
-
[56]
V . Havlíˇcek, A. D. Córcoles, K. Temme, A. W. Harrow, A. Kan- dala, J. M. Chow, and J. M. Gambetta, Supervised learning with quantum-enhanced feature spaces, Nature 567, 209 (2019)
work page 2019
-
[57]
I. A. Luchnikov, M. E. Krechetov, and S. N. Filippov, Rieman- nian geometry and automatic differentiation for optimization problems of quantum physics and quantum technologies, New Journal of Physics 23, 073006 (2021)
work page 2021
-
[58]
K. Mitarai, M. Negoro, M. Kitagawa, and K. Fujii, Quantum circuit learning, Phys. Rev. A 98, 032309 (2018)
work page 2018
- [59]
-
[60]
M. Larocca, S. Thanasilp, S. Wang, K. Sharma, J. Bia- monte, P. J. Coles, L. Cincio, J. R. McClean, Z. Holmes, and M. Cerezo, Barren plateaus in variational quantum computing, Nature Reviews Physics 7, 174 (2025)
work page 2025
-
[61]
A. Javadi-Abhari, M. Treinish, K. Krsulich, C. J. Wood, J. Lish- man, J. Gacon, S. Martiel, P. D. Nation, L. S. Bishop, A. W. Cross, B. R. Johnson, and J. M. Gambetta, Quantum comput- ing with Qiskit (2024), arXiv:2405.08810 [quant-ph]
work page internal anchor Pith review Pith/arXiv arXiv 2024
-
[62]
PennyLane: Automatic differentiation of hybrid quantum-classical computations
V . Bergholm, J. Izaac, M. Schuld, C. Gogolin, S. Ahmed, V . Ajith, M. S. Alam, G. Alonso-Linaje, B. AkashNarayanan, A. Asadi, J. M. Arrazola, U. Azad, S. Banning, C. Blank, T. R. Bromley, B. A. Cordier, J. Ceroni, A. Delgado, O. D. Matteo, A. Dusko, T. Garg, D. Guala, A. Hayes, R. Hill, A. Ijaz, T. Isac- sson, D. Ittah, S. Jahangiri, P. Jain, E. Jiang, A...
work page internal anchor Pith review Pith/arXiv arXiv 2022
-
[63]
J. Gray, quimb: A python package for quantum information and many-body calculations, Journal of Open Source Software 3, 819 (2018)
work page 2018
-
[64]
J. I. S. Johri and E. Y . Zhu, Quantum state preparation of normal distributions using matrix product states, npj Quantum Informa- tion 10, 15 (2024)
work page 2024
-
[65]
V . Bohun, I. Lukin, M. Luhanko, G. Korpas, P. J. S. D. Brouwer, M. Maksymenko, and M. Koch-Janusz, Entanglement scaling in matrix product state representation of smooth func- tions and their shallow quantum circuit approximations (2025), arXiv:2412.05202 [quant-ph]
work page internal anchor Pith review arXiv 2025
-
[66]
A. Kandala, A. Mezzacapo, K. Temme, M. Takita, M. Brink, J. M. Chow, and J. M. Gambetta, Hardware-efficient variational quantum eigensolver for small molecules and quantum mag- nets, Nature 549, 242 (2017). 8
work page 2017
-
[67]
S. T. Jose and O. Simeone, Error-mitigation-aided optimiza- tion of parameterized quantum circuits: Convergence analysis, IEEE Transactions on Quantum Engineering 3, 1 (2022)
work page 2022
-
[68]
K. Zhang, L. Liu, M.-H. Hsieh, and D. Tao, Escaping from the barren plateau via gaussian initializations in deep varia- tional quantum circuits, inAdvances in Neural Information Pro- cessing Systems , V ol. 35, edited by S. Koyejo, S. Mohamed, A. Agarwal, D. Belgrave, K. Cho, and A. Oh (Curran Asso- ciates, Inc., 2022) pp. 18612–18627
work page 2022
- [69]
-
[70]
H. Manabe and Y . Sano, The state preparation of multivari- ate normal distributions using tree tensor network (2025), arXiv:2412.12067 [quant-ph]
-
[71]
I. V . Oseledets, Tensor-train decomposition, SIAM Journal on Scientific Computing 33, 2295 (2011)
work page 2011
-
[72]
I. Oseledets and E. Tyrtyshnikov, Tt-cross approximation for multidimensional arrays, Linear Algebra and its Applications 432, 70 (2010)
work page 2010
-
[73]
M. Rosenkranz, E. Brunner, G. Marin-Sanchez, N. Fitzpatrick, S. Dilkes, Y . Tang, Y . Kikuchi, and M. Benedetti, Quantum state preparation for multivariate functions, Quantum9, 1703 (2025)
work page 2025
-
[74]
J. J. García-Ripoll, Quantum-inspired algorithms for multivari- ate analysis: from interpolation to partial differential equations, Quantum 5, 431 (2021)
work page 2021
-
[75]
The default gate set consists of 1 , Rz, SX , X and CX gates
-
[76]
F. Hayes, S. Croke, C. Messenger, and F. Speirits, Quantum state preparation of gravitational waves (2023), arXiv:2306.11073 [quant-ph]. MPO bond dimension We now study how the bond dimension of the matrix product operator (MPO) [42] representation of a PQC unitary depends on the number of layers. The PQC has parallel CNOT layers as presented in Fig. 3. I...
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