Recognition: no theorem link
Fault-Tolerant One-Shot Entanglement Generation with Constant-Sized Quantum Devices in the Plane
Pith reviewed 2026-05-10 18:31 UTC · model grok-4.3
The pith
A rectangular grid of constant-size quantum devices generates high-fidelity entanglement over arbitrary distances using only local operations in one shot, provided noise stays below a fixed threshold.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
Below a constant threshold on local stochastic Pauli noise, a rectangular grid of qubits of size Θ(R) by Θ(poly(log R)) suffices to produce a constant-fidelity Bell pair between qubits distance R apart. The protocol applies single-qubit and nearest-neighbor two-qubit operations in one shot and leaves the output in a Bell state up to a known Pauli correction. The same construction gives a 2D-local stabilizer Hamiltonian whose Gibbs states at constant positive temperature possess long-range localizable entanglement.
What carries the argument
A one-shot local protocol that uses many-body entanglement across the grid to distill long-range entanglement while correcting errors with constant-size blocks.
If this is right
- Quantum repeater stations can remain constant size while still supporting entanglement over unlimited distances.
- A 2D-local stabilizer Hamiltonian exists whose thermal states retain long-range localizable entanglement at any fixed positive temperature below some threshold.
- Entanglement generation between distance-R qubits requires only polylogarithmic growth in one grid dimension rather than linear growth in both.
- The protocol applies equally to geometrically limited single devices and to planar networks of small repeater units.
Where Pith is reading between the lines
- If the noise threshold is high enough to be reachable in hardware, the construction could simplify the design of large-scale quantum networks by removing the need for distance-dependent processor sizes.
- The same grid-based many-body state might be adaptable to other noise models or to three dimensions, though the paper does not explore those cases.
- The existence of a constant-temperature Gibbs state with long-range entanglement suggests that thermal noise alone need not destroy useful quantum correlations in suitably engineered 2D systems.
Load-bearing premise
Local stochastic Pauli noise must remain below some fixed positive strength so that the error-correction and distillation steps keep the output fidelity bounded away from zero.
What would settle it
Implement the protocol on successively larger grids and measure the fidelity of the output Bell pair; if the fidelity falls toward zero as distance R increases while noise stays fixed below the claimed threshold, the scaling claim is false.
Figures
read the original abstract
Consider a rectangular grid of qubits in 2D with single-qubit and nearest-neighbor two-qubit operations subject to local stochastic Pauli noise. At different length scales, this setup describes both a single quantum computing device with geometrically limited connectivity between qubits arranged on a disc, and planar networks composed of quantum repeater stations of constant size. We give a protocol which robustly generates entanglement between distant qubits in this setup. For noise below a constant threshold error strength, it generates a constant-fidelity Bell pair between qubits separated by an arbitrarily large distance $R$. To generate distance-$R$ entanglement, a rectangular grid of qubits of dimensions $\Theta(R)\times \Theta(\mathsf{poly}(\log R))$ suffices. Our protocol applies quantum operations in one shot, establishing a Bell state in a constant time up to a known Pauli correction. In contrast, existing entanglement generation protocols either require local quantum devices controlling a number of qubits growing with the targeted distance, or are not single-shot, i.e., have a distance-dependent execution time. The protocol leverages many-body entanglement in networks and provides the first example of a short-range entangled state in 2D with long-range localizable entanglement robust to local stochastic Pauli noise. As an immediate corollary, we construct a 2D-local stabilizer Hamiltonian whose Gibbs states possess long-range localizable entanglement at constant positive temperature.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The manuscript presents a protocol for generating a constant-fidelity Bell pair between qubits separated by arbitrary distance R in a 2D rectangular grid subject to local stochastic Pauli noise. The protocol uses only single-qubit and nearest-neighbor two-qubit gates applied in one shot (constant time, up to a known Pauli correction) and requires a grid of size Θ(R) × Θ(poly(log R)). It claims a constant noise threshold below which the fidelity remains bounded away from 1/2 independently of R. As a corollary, the authors construct a 2D-local stabilizer Hamiltonian whose Gibbs states exhibit long-range localizable entanglement at constant positive temperature. The work contrasts this with prior entanglement-generation schemes that require either distance-dependent device sizes or multiple rounds of communication.
Significance. If the central claims hold, the result supplies the first explicit example of a short-range entangled 2D state whose localizable entanglement remains long-range and robust under local stochastic Pauli noise. The constant threshold together with poly(log R) width scaling and one-shot execution would be a substantial advance for planar quantum networks and repeater architectures that must remain constant-sized. The Hamiltonian corollary also links the construction to finite-temperature many-body physics, which is a non-trivial byproduct.
major comments (2)
- [§4 and §5] §4 (Protocol Construction) and §5 (Error Analysis): the argument that the logical error per segment decays exponentially in the poly(log R) width while the total accumulated error over length R remains O(1) is load-bearing for the constant-threshold claim. The manuscript must supply an explicit bound (or reference to a standard strip-code or renormalization lemma) showing that the chosen polynomial degree suffices for any fixed noise rate below the threshold; without this quantitative step the scaling statement is not yet fully supported.
- [§6] §6 (Hamiltonian Corollary): the mapping from the one-shot protocol to a 2D-local stabilizer Hamiltonian whose thermal states retain long-range localizable entanglement is stated but the temperature range and the explicit form of the Hamiltonian are not derived in detail. This step is required to substantiate the “constant positive temperature” claim.
minor comments (3)
- [Abstract and §1] The abstract and introduction use “poly(log R)” without specifying the degree; a brief remark on the minimal exponent required by the error analysis would improve readability.
- [Figure 2] Figure 2 (grid layout) would benefit from an explicit indication of the measurement pattern or the locations of the final Bell-pair qubits.
- [§2] A short comparison table listing resource scaling, execution time, and threshold for the new protocol versus the main prior works cited in §2 would help readers assess the improvement.
Simulated Author's Rebuttal
We thank the referee for the careful reading, the positive assessment of significance, and the recommendation for minor revision. We address each major comment below and will incorporate the requested clarifications into the revised manuscript.
read point-by-point responses
-
Referee: [§4 and §5] the argument that the logical error per segment decays exponentially in the poly(log R) width while the total accumulated error over length R remains O(1) is load-bearing for the constant-threshold claim. The manuscript must supply an explicit bound (or reference to a standard strip-code or renormalization lemma) showing that the chosen polynomial degree suffices for any fixed noise rate below the threshold; without this quantitative step the scaling statement is not yet fully supported.
Authors: We agree that an explicit quantitative bound strengthens the presentation. In the revised version we will add a self-contained lemma in §5 (Error Analysis) that derives the logical error rate per segment as at most exp(−c·w) for width w = Θ(poly(log R)), where the constant c > 0 depends only on the noise rate p below the threshold. The lemma combines a standard renormalization argument for 1D repetition-like codes on strips with a union bound over the Θ(R) segments; the poly(log R) degree is chosen large enough that the per-segment failure probability is O(1/R), keeping the total accumulated logical error bounded by a constant independent of R. We will also cite the relevant strip-code literature for completeness. revision: yes
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Referee: [§6] the mapping from the one-shot protocol to a 2D-local stabilizer Hamiltonian whose thermal states retain long-range localizable entanglement is stated but the temperature range and the explicit form of the Hamiltonian are not derived in detail. This step is required to substantiate the “constant positive temperature” claim.
Authors: We will expand §6 to give the explicit construction: the Hamiltonian is the sum of local stabilizer projectors corresponding to the syndrome measurements performed by the protocol (each term acts on a constant number of neighboring qubits). We derive that for any inverse temperature β larger than a constant β0(p) determined by the noise threshold p, the thermal state satisfies the same localizable-entanglement lower bound as the zero-temperature protocol state, up to an exponentially small correction in the system size. The proof uses the standard Peierls argument together with the fact that the protocol’s error correction succeeds with high probability under the thermal noise model. revision: yes
Circularity Check
No significant circularity in derivation chain
full rationale
The protocol is built from standard single-qubit and nearest-neighbor two-qubit gates under local stochastic Pauli noise below a constant threshold. The claimed scaling (Θ(R) × Θ(poly(log R)) grid for distance-R entanglement) and one-shot property follow from the explicit construction of a renormalization-style or strip-code scheme in which logical error decays exponentially with width while total error over length R remains bounded. No load-bearing step reduces to a fitted parameter renamed as prediction, a self-citation chain, or a self-definitional ansatz; the threshold existence and robustness are external to the present derivation and the corollary Hamiltonian is obtained directly from the protocol without circular redefinition. The derivation is therefore self-contained against the stated noise model and geometric constraints.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption Local stochastic Pauli noise model with strength below a constant threshold allows fault-tolerant operations.
Reference graph
Works this paper leans on
-
[1]
Ignacio Cirac, and Maciej Lewenstein
Antonio Acín, J. Ignacio Cirac, and Maciej Lewenstein. Entanglement percolation in quan- tum networks.Nature Physics, 3(4):256–259, 2007
2007
-
[2]
Fault-tolerant quantum computation with constant error
Dorit Aharonov and Michael Ben-Or. Fault-tolerant quantum computation with constant error. InProceedings of the 29th ACM symposium on Theory of Computing, pages 176–188, 1997
1997
-
[3]
Level reduction and the quantum threshold theorem.Ph.D
Panagiotis Panos Aliferis. Level reduction and the quantum threshold theorem.Ph.D. Thesis, 2007
2007
-
[4]
Quantum accuracy threshold for concatenated distance-3 codes.Quantum Info
Panos Aliferis, Daniel Gottesman, and John Preskill. Quantum accuracy threshold for concatenated distance-3 codes.Quantum Info. Comput., 6(2):97–165, 2006
2006
-
[5]
Economou, David Elkouss, Paul Hilaire, Liang Jiang, Hoi-Kwong Lo, and Ilan Tzitrin
Koji Azuma, Sophia E. Economou, David Elkouss, Paul Hilaire, Liang Jiang, Hoi-Kwong Lo, and Ilan Tzitrin. Quantum repeaters: From quantum networks to the quantum internet. Reviews of Modern Physics, 95(4):045006, 2023
2023
-
[6]
High-temperature Gibbs states are unentangled and efficiently preparable
Ainesh Bakshi, Allen Liu, Ankur Moitra, and Ewin Tang. High-temperature Gibbs states are unentangled and efficiently preparable. In2024 IEEE 65th Annual Symposium on Foundations of Computer Science (FOCS), pages 1027–1036. IEEE, 2024
2024
-
[7]
Paula Belzig and Hayata Yamasaki. Constant-space-overhead fault-tolerant quantum in- put/output and communication.arXiv preprint arXiv:2602.09103, 2026
-
[8]
Bennett and Gilles Brassard
Charles H. Bennett and Gilles Brassard. Quantum cryptography: Public key distribution and coin tossing.Theoretical computer science, 560:7–11, 2014
2014
-
[9]
Bennett, Gilles Brassard, Claude Crépeau, Richard Jozsa, Asher Peres, and WilliamK.Wootters
Charles H. Bennett, Gilles Brassard, Claude Crépeau, Richard Jozsa, Asher Peres, and WilliamK.Wootters. TeleportinganunknownquantumstateviadualclassicalandEinstein- Podolsky-Rosen channels.Physical Review Letters, 70(13):1895, 1993
1993
-
[10]
ThiagoBergamaschiandYunchaoLiu. Onfaulttolerantsingle-shotlogicalstatepreparation and robust long-range entanglement.arXiv preprint arXiv:2411.04405, 2024
-
[11]
Quantum advantage with noisy shallow circuits.Nature Physics, 16(10):1040–1045, 2020
Sergey Bravyi, David Gosset, Robert König, and Marco Tomamichel. Quantum advantage with noisy shallow circuits.Nature Physics, 16(10):1040–1045, 2020
2020
-
[12]
Obstacles to variational quantum optimization from symmetry protection.Physical Review Letters, 125:260505, Dec 2020
Sergey Bravyi, Alexander Kliesch, Robert Koenig, and Eugene Tang. Obstacles to variational quantum optimization from symmetry protection.Physical Review Letters, 125:260505, Dec 2020
2020
-
[13]
Briegel, W Dür, J
H.-J. Briegel, W Dür, J. I. Cirac, and P. Zoller. Quantum repeaters: The role of imperfect local operations in quantum communication.Physical Review Letters, 81(26):5932–5935, 1998
1998
-
[14]
Briegel and Robert Raussendorf
Hans J. Briegel and Robert Raussendorf. Persistent entanglement in arrays of interacting particles.Physical Review Letters, 86(5):910, 2001
2001
-
[15]
Local unitary transformation, long-range quantum entanglement, wave function renormalization, and topological order.Phys
Xie Chen, Zheng-Cheng Gu, and Xiao-Gang Wen. Local unitary transformation, long-range quantum entanglement, wave function renormalization, and topological order.Phys. Rev. B, 82:155138, Oct 2010. 73
2010
-
[16]
Childress, J
L. Childress, J. M. Taylor, A. S. Sørensen, and M. D. Lukin. Fault-tolerant quantum repeaters with minimal physical resources and implementations based on single-photon emitters.Physical Review A, 72:052330, Nov 2005
2005
-
[17]
Childs, Eddie Schoute, and Cem M
Andrew M. Childs, Eddie Schoute, and Cem M. Unsal. Circuit Transformations for Quan- tum Architectures. In Wim van Dam and Laura Mančinska, editors,14th Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC 2019), volume 135 ofLeibniz International Proceedings in Informatics (LIPIcs), pages 3:1–3:24, Dagstuhl, Germany, 2019....
2019
-
[18]
Chiribella, G
G. Chiribella, G. M. D’Ariano, and P. Perinotti. Quantum circuit architecture.Physical Review Letters, 101(6), August 2008
2008
-
[19]
Long-range data transmission in a fault-tolerant quantum bus architecture.npj Quantum Information, 10(1):132, 2024
Shin Ho Choe and Robert König. Long-range data transmission in a fault-tolerant quantum bus architecture.npj Quantum Information, 10(1):132, 2024
2024
-
[20]
How to fault-tolerantly realize any quantum circuit with local operations.PRX Quantum, 6(1):010357, 2025
Shin Ho Choe and Robert König. How to fault-tolerantly realize any quantum circuit with local operations.PRX Quantum, 6(1):010357, 2025
2025
-
[21]
Fault-tolerant quantum in- put/output.IEEE Transactions on Information Theory, 2026
Matthias Christandl, Omar Fawzi, and Ashutosh Goswami. Fault-tolerant quantum in- put/output.IEEE Transactions on Information Theory, 2026
2026
-
[22]
DiVincenzo and Panos Aliferis
David P. DiVincenzo and Panos Aliferis. Effective fault-tolerant quantum computation with slow measurements.Physical Review Letters, 98(2):020501, 2007
2007
-
[23]
Fowler, David S
Austin G. Fowler, David S. Wang, Charles D. Hill, Thaddeus D. Ladd, Rodney Van Meter, and Lloyd C. L. Hollenberg. Surface code quantum communication.Physical Review Letters, 104(18):180503, 2010
2010
-
[24]
A constant rate quantum computer on a line.arXiv preprint arXiv:2502.16132, 2025
Craig Gidney and Thiago Bergamaschi. A constant rate quantum computer on a line.arXiv preprint arXiv:2502.16132, 2025
-
[25]
Fault-tolerant quantum computation with local gates.Journal of Mod- ern Optics, 47(2-3):333–345, 2000
Daniel Gottesman. Fault-tolerant quantum computation with local gates.Journal of Mod- ern Optics, 47(2-3):333–345, 2000
2000
-
[26]
An introduction to quantum error correction and fault-tolerant quantum computation, 2009
Daniel Gottesman. An introduction to quantum error correction and fault-tolerant quantum computation, 2009
2009
-
[27]
Fault-tolerant quantum computation with constant overhead.Quantum Information & Computation, 14(15-16):1338–1372, 2014
Daniel Gottesman. Fault-tolerant quantum computation with constant overhead.Quantum Information & Computation, 14(15-16):1338–1372, 2014
2014
-
[28]
Surviving as a quantum computer in a classical world.Textbook manuscript preprint, 8(8.1):8–2, 2024
Daniel Gottesman. Surviving as a quantum computer in a classical world.Textbook manuscript preprint, 8(8.1):8–2, 2024
2024
-
[29]
Daniel Gottesman and Isaac L. Chuang. Demonstrating the viability of universal quantum computation using teleportation and single-qubit operations.Nature, 402(6760):390–393, November 1999
1999
-
[30]
Springer-Verlag, Berlin, 1999
Geoffrey Grimmett.Percolation. Springer-Verlag, Berlin, 1999
1999
-
[31]
Zhiyang He, Quynh T. Nguyen, and Christopher A. Pattison. Composable quantum fault- tolerance.arXiv preprint arXiv:2508.08246, 2025
-
[32]
Taylor, Kae Nemoto, William J
Liang Jiang, Jacob M. Taylor, Kae Nemoto, William J. Munro, Rodney Van Meter, and Mikhail D. Lukin. Quantum repeater with encoding.Physical Review A—Atomic, Molecu- lar, and Optical Physics, 79(3):032325, 2009. 74
2009
-
[33]
Emanuel Knill and Raymond Laflamme. Concatenated quantum codes.arXiv preprint quant-ph/9608012, 1996
work page Pith review arXiv 1996
-
[34]
D. Kőnig. Gráfok és mátrixok.Matematikai és Fizikai Lapok, 38:116–119, 1931
1931
-
[35]
G. J. Lapeyre, S. Perseguers, M. Lewenstein, and A. Acín. Distribution of entanglement in networks of bi-partite full-rank mixed states.Quantum Information & Computation, 12(5-6):502–534, 2012
2012
-
[36]
John Lapeyre Jr, Jan Wehr, and Maciej Lewenstein
G. John Lapeyre Jr, Jan Wehr, and Maciej Lewenstein. Enhancement of entanglement percolation in quantum networks via lattice transformations.Physical Review A—Atomic, Molecular, and Optical Physics, 79(4):042324, 2009
2009
-
[37]
Fromquantum multiplexing to high-performance quantum networking.Nature Photonics, 4(11):792–796, 2010
W.J.Munro, K.A.Harrison, A.M.Stephens, S.J.Devitt, andKaeNemoto. Fromquantum multiplexing to high-performance quantum networking.Nature Photonics, 4(11):792–796, 2010
2010
-
[38]
Munro, Koji Azuma, Kiyoshi Tamaki, and Kae Nemoto
William J. Munro, Koji Azuma, Kiyoshi Tamaki, and Kae Nemoto. Inside quantum re- peaters.IEEE Journal of Selected topics in quantum electronics, 21(3):78–90, 2015
2015
-
[39]
Munro, Ashley M
William J. Munro, Ashley M. Stephens, Simon J. Devitt, Keith A. Harrison, and Kae Nemoto. Quantum communication without the necessity of quantum memories.Nature Photonics, 6(11):777–781, 2012
2012
-
[40]
Lukin, and Liang Jiang
Sreraman Muralidharan, Jungsang Kim, Norbert Lütkenhaus, Mikhail D. Lukin, and Liang Jiang. Ultrafast and fault-tolerant quantum communication across long distances.Physical Review Letters, 112(25):250501, 2014
2014
-
[41]
Lukin, and Liang Jiang
Sreraman Muralidharan, Linshu Li, Jungsang Kim, Norbert Lütkenhaus, Mikhail D. Lukin, and Liang Jiang. Optimal architectures for long distance quantum communication.Scien- tific reports, 6(1):20463, 2016
2016
-
[42]
Over- coming erasure errors with multilevel systems.New Journal of Physics, 19(1):013026, 2017
Sreraman Muralidharan, Chang-Ling Zou, Linshu Li, Jianming Wen, and Liang Jiang. Over- coming erasure errors with multilevel systems.New Journal of Physics, 19(1):013026, 2017
2017
-
[43]
Fidelity threshold for long-range entanglement in quantum networks
Sébastien Perseguers. Fidelity threshold for long-range entanglement in quantum networks. Physical Review A—Atomic, Molecular, and Optical Physics, 81(1):012310, 2010
2010
-
[44]
Cavalcanti, G
Sébastien Perseguers, D. Cavalcanti, G. J. Lapeyre Jr, M. Lewenstein, and A. Acín. Mul- tipartite entanglement percolation.Physical Review A—Atomic, Molecular, and Optical Physics, 81(3):032327, 2010
2010
-
[45]
Ignacio Cirac, Antonio Acín, Maciej Lewenstein, and Jan Wehr
Sébastien Perseguers, J. Ignacio Cirac, Antonio Acín, Maciej Lewenstein, and Jan Wehr. Entanglement distribution in pure-state quantum networks.Physical Review A—Atomic, Molecular, and Optical Physics, 77(2):022308, 2008
2008
-
[46]
Sebastien Perseguers, Liang Jiang, Norbert Schuch, Frank Verstraete, M. D. Lukin, J. Igna- cio Cirac, and Karl G. H. Vollbrecht. One-shot entanglement generation over long distances in noisy quantum networks.Physical Review A—Atomic, Molecular, and Optical Physics, 78(6):062324, 2008
2008
-
[47]
M. Popp, F. Verstraete, M. A. Martín-Delgado, and J. I. Cirac. Localizable entanglement. Phys. Rev. A, 71:042306, Apr 2005. 75
2005
-
[48]
Long-range quantum entangle- ment in noisy cluster states.Physical Review A—Atomic, Molecular, and Optical Physics, 71(6):062313, 2005
Robert Raussendorf, Sergey Bravyi, and Jim Harrington. Long-range quantum entangle- ment in noisy cluster states.Physical Review A—Atomic, Molecular, and Optical Physics, 71(6):062313, 2005
2005
-
[49]
Alhambra
Cambyse Rouzé, Daniel Stilck França, and Álvaro M. Alhambra. Efficient thermalization and universal quantum computing with quantum Gibbs samplers. InProceedings of the 57th Annual ACM Symposium on Theory of Computing, pages 1488–1495, 2025
2025
-
[50]
Quantum repeatersbasedonatomicensemblesandlinearoptics.Reviews of Modern Physics, 83(1):33– 80, 2011
Nicolas Sangouard, Christoph Simon, Hugues De Riedmatten, and Nicolas Gisin. Quantum repeatersbasedonatomicensemblesandlinearoptics.Reviews of Modern Physics, 83(1):33– 80, 2011
2011
-
[51]
A. M. Steane. Active stabilization, quantum computation, and quantum state synthesis. Physical Review Letters, 78:2252–2255, Mar 1997
1997
-
[52]
Multiple-particle interference and quantum error correction.Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 452(1954):2551– 2577, 11 1996
Andrew Steane. Multiple-particle interference and quantum error correction.Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences, 452(1954):2551– 2577, 11 1996
1954
-
[53]
Andrew M. Steane. Error correcting codes in quantum theory.Physical Review Letters, 77(5):793, 1996
1996
-
[54]
A. M. Stephens, A. G. Fowler, and L. C. L. Hollenberg. Universal fault tolerant quantum computation on bilinear nearest neighbor arrays.Quantum Info. Comput., 8(3):330–344, March 2008
2008
-
[55]
V. G. Vizing. On an estimate of the chromatic class of ap-graph.Diskret. Analiz, (3):25–30, 1964
1964
-
[56]
Time-efficient constant-space-overhead fault-tolerant quantum computation.Nature Physics, 20(2):247–253, 2024
Hayata Yamasaki and Masato Koashi. Time-efficient constant-space-overhead fault-tolerant quantum computation.Nature Physics, 20(2):247–253, 2024
2024
-
[57]
Event-ready-detectors
Marek Zukowski, Anton Zeilinger, M. Horne, and Artur Ekert. “Event-ready-detectors” Bell experiment via entanglement swapping.Physical Review Letters, 71(26), 1993
1993
-
[58]
Zwerger, H
M. Zwerger, H. J. Briegel, and W. Dür. Hybrid architecture for encoded measurement-based quantum computation.Scientific reports, 4(1):5364, 2014. 76
2014
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