Generating Non-Decomposable Maps with Differentiable Semidefinite Programming
Pith reviewed 2026-06-30 20:38 UTC · model grok-4.3
The pith
Differentiable semidefinite programming generates positive non-decomposable maps under chosen constraints on their Choi matrices.
A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.
Core claim
We introduce an optimization framework based on differentiable semidefinite programming (SDP) for generating positive non-decomposable maps under flexible structural constraints on their Choi matrices. The method combines SDP-based certificates of non-decomposability and positivity with gradient-based optimization, enabling a systematic search over maps with different input and output dimensions. Within this framework, we generate previously unknown numerical examples, identify a parametrized family of maps arising from masked Choi matrices, and construct real non-decomposable maps. We further show that the same approach can be adapted to explore open questions in quantum information theory,
What carries the argument
Differentiable semidefinite programming that optimizes Choi matrices subject to SDP certificates of positivity and non-decomposability.
If this is right
- New numerical examples of positive non-decomposable maps become available in chosen dimensions.
- A parametrized family of maps is obtained directly from masked Choi matrices.
- Real (non-numerical) non-decomposable maps can be constructed within the same procedure.
- The framework extends to test the PPT square conjecture and proposed eigenvalue bounds on 2-positive maps.
Where Pith is reading between the lines
- The method may scale to higher-dimensional maps once the SDP solvers are replaced by faster approximations.
- The generated families could supply concrete counter-examples or supporting evidence for conjectures on map decomposability.
- Similar differentiable-SDP pipelines might apply to other positivity constraints, such as k-positivity for k>1.
Load-bearing premise
The SDP certificates correctly certify that the optimized maps remain positive and non-decomposable, and the gradient optimization stays inside the feasible set.
What would settle it
An explicit example in which the output of the optimization procedure yields a map that the SDP certificate labels non-decomposable yet an independent analytic check shows it is decomposable.
Figures
read the original abstract
Positive maps that are not decomposable are a key resource in entanglement theory because they can detect bound entangled states, yet systematic methods for constructing them remain limited. We introduce an optimization framework based on differentiable semidefinite programming (SDP) for generating positive non-decomposable maps under flexible structural constraints on their Choi matrices. The method combines SDP-based certificates of non-decomposability and positivity with gradient-based optimization, enabling a systematic search over maps with different input and output dimensions. Within this framework, we generate previously unknown numerical examples, identify a parametrized family of maps arising from masked Choi matrices, and construct real non-decomposable maps. We further show that the same approach can be adapted to explore open questions in quantum information theory, including the PPT square conjecture and recently proposed eigenvalue bounds for 2-positive trace-preserving maps.
Editorial analysis
A structured set of objections, weighed in public.
Referee Report
Summary. The paper claims to introduce an optimization framework based on differentiable semidefinite programming (SDP) for generating positive non-decomposable maps under flexible structural constraints on their Choi matrices. It combines SDP-based certificates of non-decomposability and positivity with gradient-based optimization to enable systematic search over maps with varying dimensions, reports previously unknown numerical examples, identifies a parametrized family arising from masked Choi matrices, constructs real non-decomposable maps, and adapts the method to explore the PPT square conjecture and eigenvalue bounds for 2-positive trace-preserving maps.
Significance. If the central claims hold, the framework offers a systematic numerical tool for constructing positive maps that are not decomposable, which are important resources for detecting bound entanglement. The combination of SDP certificates with gradient optimization under flexible constraints on Choi matrices is a methodological strength that could facilitate discovery of new families and exploration of open problems such as the PPT square conjecture.
major comments (2)
- [§3] §3 (Optimization framework): The method backpropagates through SDP solution maps to optimize Choi-matrix parameters for positivity and non-decomposability. No verification is provided that the converged optima satisfy conditions required for reliable differentiability (e.g., uniqueness of the optimal solution or strict complementarity). Standard SDP theory shows that the solution map fails to be differentiable when these fail; without analysis or numerical checks confirming the reported examples lie in the differentiable regime, the validity of the generated maps and the systematic search rests on an unverified assumption.
- [§4] §4 (Numerical results and examples): The reported examples and parametrized families are obtained via the differentiable SDP procedure, yet the manuscript does not name the SDP solver, report any regularization or uniqueness safeguards, or include post-optimization checks (e.g., eigenvalue gaps or multiplicity) that would confirm gradients were reliable at the reported points. This directly affects the load-bearing claim that new non-decomposable maps have been systematically generated.
minor comments (2)
- [Introduction] The distinction between 'numerical' and 'real' non-decomposable maps is mentioned in the abstract but receives insufficient clarification in the introduction or methods regarding how the real maps are obtained from the optimization output.
- [§2] Notation for the Choi matrix constraints and the precise form of the non-decomposability certificate could be made more explicit with an additional equation or table summarizing the SDP formulations used.
Simulated Author's Rebuttal
We thank the referee for the careful reading and constructive major comments on the differentiability and numerical verification of our differentiable SDP framework. We address each point below and will revise the manuscript accordingly to strengthen the reliability claims.
read point-by-point responses
-
Referee: [§3] §3 (Optimization framework): The method backpropagates through SDP solution maps to optimize Choi-matrix parameters for positivity and non-decomposability. No verification is provided that the converged optima satisfy conditions required for reliable differentiability (e.g., uniqueness of the optimal solution or strict complementarity). Standard SDP theory shows that the solution map fails to be differentiable when these fail; without analysis or numerical checks confirming the reported examples lie in the differentiable regime, the validity of the generated maps and the systematic search rests on an unverified assumption.
Authors: We agree that the manuscript does not explicitly verify the differentiability conditions (uniqueness and strict complementarity) required by SDP theory for the solution map to be differentiable. While the reported examples were obtained via standard backpropagation through an SDP solver and produced consistent results, this constitutes a genuine gap in the presentation. In the revised manuscript we will add a discussion of these theoretical requirements together with post-optimization numerical checks (eigenvalue gaps and multiplicity) confirming that the converged points satisfy the conditions for reliable gradients. These additions will directly support the validity of the generated maps. revision: yes
-
Referee: [§4] §4 (Numerical results and examples): The reported examples and parametrized families are obtained via the differentiable SDP procedure, yet the manuscript does not name the SDP solver, report any regularization or uniqueness safeguards, or include post-optimization checks (e.g., eigenvalue gaps or multiplicity) that would confirm gradients were reliable at the reported points. This directly affects the load-bearing claim that new non-decomposable maps have been systematically generated.
Authors: The referee is correct that the manuscript omits the SDP solver name, regularization details, and post-optimization diagnostics. We will revise §4 to name the solver, describe any regularization used to promote uniqueness, and incorporate the eigenvalue-gap and multiplicity checks referenced in our response to the §3 comment. These changes will provide the requested safeguards and reinforce the systematic-generation claim without altering the reported examples or families. revision: yes
Circularity Check
No circularity; computational optimization framework uses external SDP solvers
full rationale
The paper presents a method that combines SDP certificates of positivity and non-decomposability with gradient-based optimization over Choi-matrix parameters to generate examples of positive non-decomposable maps. No derivation reduces a claimed result to a fitted parameter or self-citation by construction; the outputs are numerical maps and parametrized families obtained via the external optimization procedure rather than internal redefinitions. The approach is self-contained against external benchmarks (SDP solvers and gradient methods) with no load-bearing self-referential steps in the abstract or described chain.
Axiom & Free-Parameter Ledger
axioms (1)
- domain assumption SDP-based certificates reliably detect positivity and non-decomposability of maps
Forward citations
Cited by 1 Pith paper
-
Sparse positive maps on qutrits with exact nondecomposability thresholds and PPT-entanglement transitions
Exact positivity boundaries, nondecomposability transitions, and PPT-entanglement thresholds are derived for three parametric families of sparse positive maps on qutrits.
Reference graph
Works this paper leans on
-
[1]
Bengtsson and K
I. Bengtsson and K. ˙Zyczkowski,Geometry of quantum states: an introduction to quantum entanglement(Cam- bridge university press, 2017)
2017
-
[2]
Horodecki, P
R. Horodecki, P. Horodecki, M. Horodecki, and K. Horodecki, Quantum entanglement, Rev. Mod. Phys. 81, 865 (2009)
2009
-
[3]
G¨ uhne and G
O. G¨ uhne and G. T´ oth, Entanglement detection, Phys. Rep.474, 1 (2009)
2009
-
[4]
Peres, Separability criterion for density matrices, Phys
A. Peres, Separability criterion for density matrices, Phys. Rev. Lett.77, 1413 (1996)
1996
-
[5]
Horodecki, P
M. Horodecki, P. Horodecki, and R. Horodecki, Separa- bility of mixed states: necessary and sufficient conditions, Phys. Lett. A223, 1 (1996)
1996
-
[6]
W. A. Majewski and M. Marciniak,k-decomposability of positive maps (2004), arXiv:quant-ph/0411035
work page internal anchor Pith review Pith/arXiv arXiv 2004
-
[7]
M¨ uller-Hermes, D
A. M¨ uller-Hermes, D. Reeb, and M. M. Wolf, Positivity of linear maps under tensor powers, J. Math. Phys.57, 015202 (2016)
2016
-
[8]
S. J. Szarek, E. Werner, and K. ˙Zyczkowski, Geometry of sets of quantum maps: a generic positive map acting on a high-dimensional system is not completely positive, J. Math. Phys.49(2008)
2008
- [9]
-
[10]
S. L. Woronowicz, Positive maps of low dimensional ma- trix algebras, Rep. Math. Phys.10, 165 (1976)
1976
-
[11]
Choi, Positive linear maps on c*-algebras, Can
M.-D. Choi, Positive linear maps on c*-algebras, Can. J. Math.24, 520 (1972)
1972
-
[12]
Benatti, R
F. Benatti, R. Floreanini, and M. Piani, Non- decomposable quantum dynamical semigroups and bound entangled states, Open Syst. Inf. Dyn.11, 325 (2004)
2004
-
[13]
Størmer, Decomposable positive maps on c*-algebras, Proc
E. Størmer, Decomposable positive maps on c*-algebras, Proc. Am. Math. Soc.86, 402 (1982)
1982
-
[14]
˙Zyczkowski and I
K. ˙Zyczkowski and I. Bengtsson, On duality between quantum maps and quantum states, Open Syst. Inf. Dyn. 11, 3 (2004)
2004
-
[15]
Balasubramanian, A note on decomposable maps on operator systems (2020), arXiv:2006.12405 [math.OA]
S. Balasubramanian, A note on decomposable maps on operator systems (2020), arXiv:2006.12405 [math.OA]
-
[16]
Skowronek and K
L. Skowronek and K. ˙Zyczkowski, Positive maps, positive polynomials and entanglement witnesses, J. Phys. A42, 325302 (2009)
2009
-
[17]
Ha and S.-H
K.-C. Ha and S.-H. Kye, Global geometric difference be- tween separable and positive partial transpose states, Open Syst. Inf. Dyn21, 1450009 (2014)
2014
-
[18]
Choi, Positive semidefinite biquadratic forms, Lin- ear Algebra Its Appl.12, 95 (1975)
M.-D. Choi, Positive semidefinite biquadratic forms, Lin- ear Algebra Its Appl.12, 95 (1975)
1975
-
[19]
B. M. Terhal, A family of indecomposable positive linear maps based on entangled quantum states, Linear Algebra Its Appl.323, 61 (2001)
2001
-
[20]
Kossakowski, A class of linear positive maps in matrix algebras, Open Syst
A. Kossakowski, A class of linear positive maps in matrix algebras, Open Syst. Inf. Dyn.10, 213 (2003)
2003
-
[21]
Chru´ sci´ nski and A
D. Chru´ sci´ nski and A. Kossakowski, Geometry of quan- tum states: new construction of positive maps, Phys. Lett. A373, 2301 (2009)
2009
-
[22]
Hou, A characterization of positive linear maps and criteria of entanglement for quantum states, J
J. Hou, A characterization of positive linear maps and criteria of entanglement for quantum states, J. Phys. A 43, 385201 (2010)
2010
-
[23]
Marciniak and A
M. Marciniak and A. Rutkowski, Merging of positive maps: A construction of various classes of positive maps on matrix algebras, Linear Algebra Its Appl.529, 215 (2017)
2017
-
[24]
Jannesary, V
V. Jannesary, V. Karimipour, and D. Chru´ sci´ nski, A class of entanglement witnesses and a realignment-like crite- rion, Sci. Rep.15, 5718 (2025)
2025
-
[25]
M¨ uller-Hermes, Decomposability of linear maps under tensor powers, J
A. M¨ uller-Hermes, Decomposability of linear maps under tensor powers, J. Math. Phys.59, 102203 (2018)
2018
-
[26]
Benatti, R
F. Benatti, R. Floreanini, and M. Piani, Quantum dynamical semigroups and non-decomposable positive maps, Phys. Lett. A326, 187 (2004)
2004
-
[27]
On the origin of non-decomposable maps
W. Majewski, On the origin of non-decomposable maps (2017), arXiv:1706.07945 [quant-ph]
work page internal anchor Pith review Pith/arXiv arXiv 2017
-
[28]
Bhattacharya, S
B. Bhattacharya, S. Goswami, R. Mundra, N. Ganguly, I. Chakrabarty, S. Bhattacharya, and A. Majumdar, Generating and detecting bound entanglement in two- qutrits using a family of indecomposable positive maps, J. Phys. Commun.5, 065008 (2021)
2021
-
[29]
J. P. Zwolak and D. Chru´ sci´ nski, New tools for inves- tigating positive maps in matrix algebras, Rep. Math. Phys.71, 163 (2013)
2013
- [30]
-
[31]
M lynik, H
T. M lynik, H. Osaka, and M. Marciniak, Characteriza- tion of k-positive maps, Commun. Math. Phys.406, 62 (2025)
2025
-
[32]
Ha and S.-H
K.-C. Ha and S.-H. Kye, Exposedness of choi-type entan- glement witnesses and applications to lengths of separa- ble states, Open Syst. Inf. Dyn.20, 1350012 (2013)
2013
-
[33]
S. J. Cho, S.-H. Kye, and S. G. Lee, Generalized choi maps in three-dimensional matrix algebra, Linear Alge- bra Its Appl.171, 213 (1992)
1992
-
[34]
Chru´ sci´ nski, M
D. Chru´ sci´ nski, M. Marciniak, and A. Rutkowski, Gen- eralizing choi-like maps, Acta Math. Vietnam.43, 661 (2018)
2018
-
[35]
Jafarizadeh, M
M. Jafarizadeh, M. Rezaee, and S. Ahadpour, General- ized qudit choi maps, Phys. Rev. A74, 042335 (2006)
2006
-
[36]
vom Ende, S
F. vom Ende, S. Khatri, and S. Denisov, k-positive maps: New characterizations and a generation method, Open Syst. Inf. Dyn.32, 2550015 (2025)
2025
-
[37]
Kye, Facial structures for various notions of pos- itivity and applications to the theory of entanglement, Rev
S.-H. Kye, Facial structures for various notions of pos- itivity and applications to the theory of entanglement, Rev. Math. Phys.25, 1330002 (2013). 10
2013
-
[38]
Vandenberghe and S
L. Vandenberghe and S. Boyd, Semidefinite program- ming, SIAM Rev.38, 49 (1996)
1996
-
[39]
Skrzypczyk and D
P. Skrzypczyk and D. Cavalcanti,Semidefinite program- ming in quantum information science(IOP Publishing, 2023)
2023
-
[40]
Mironowicz, Semi-definite programming and quantum information, J
P. Mironowicz, Semi-definite programming and quantum information, J. Phys. A: Math. Theor.57, 163002 (2024)
2024
-
[41]
Audenaert and B
K. Audenaert and B. De Moor, Optimizing completely positive maps using semidefinite programming, Phys. Rev. A65, 030302 (2002)
2002
-
[42]
A. C. Doherty, P. A. Parrilo, and F. M. Spedalieri, Com- plete family of separability criteria, Phys. Rev. A69, 022308 (2004)
2004
-
[43]
A. C. Doherty, Entanglement and the shareability of quantum states, J. Phys. A47, 424004 (2014)
2014
-
[44]
K. Wu, Z. Chen, Z.-P. Xu, Z. Ma, and S.-M. Fei, Hy- brid of gradient descent and semidefinite programming for certifying multipartite entanglement structure, Adv. Quantum Technol.8, 2400443 (2025)
2025
-
[45]
Q. Chen, B. Collins, and O. Fawzi, Symmetry reduction for testing k-block-positivity via extendibility, J. Phys. A 58, 485302 (2025)
2025
- [46]
-
[47]
Choi, Completely positive linear maps on complex matrices, Linear Algebra Its Appl.10, 285 (1975)
M.-D. Choi, Completely positive linear maps on complex matrices, Linear Algebra Its Appl.10, 285 (1975)
1975
-
[48]
G¨ artner and J
B. G¨ artner and J. Matousek,Approximation algorithms and semidefinite programming(Springer Science & Busi- ness Media, 2012)
2012
-
[49]
Agrawal, R
A. Agrawal, R. Verschueren, S. Diamond, and S. Boyd, A rewriting system for convex optimization problems, J. Control Decis.5, 42 (2018)
2018
-
[50]
D. P. Kingma and J. Ba, Adam: A method for stochastic optimization (2014), arXiv:1412.6980 [cs.LG]
work page internal anchor Pith review Pith/arXiv arXiv 2014
-
[51]
Agrawal, B
A. Agrawal, B. Amos, S. Barratt, S. Boyd, S. Diamond, and J. Z. Kolter, Differentiable convex optimization lay- ers, inAdv. Neural Inf. Process. Syst., Vol. 32 (Curran Associates, Inc., 2019)
2019
-
[52]
Diamond and S
S. Diamond and S. Boyd, CVXPY: A Python-embedded modeling language for convex optimization, J. Mach. Learn. Res.17, 1 (2016)
2016
-
[53]
Poderini, A
D. Poderini, A. R. Morgillo, F. Benatti, F. Anselmi, C. Macchiavello, and M. F. Sacchi, Unpublished
-
[54]
A. G. Robertson, Positive projections onC ∗-algebras and an extremal positive map, J. Lond. Math. Soc.2, 133 (1985)
1985
-
[55]
Hall, A new criterion for indecomposability of positive maps, J
W. Hall, A new criterion for indecomposability of positive maps, J. Phys. A: Math. Gen.39, 14119 (2006)
2006
-
[56]
Breuer, Optimal entanglement criterion for mixed quantum states, Phys
H.-P. Breuer, Optimal entanglement criterion for mixed quantum states, Phys. Rev. Lett.97, 080501 (2006)
2006
-
[57]
vom Ende, D
F. vom Ende, D. Chru´ sci´ nski, G. Kimura, and P. Muratore-Ginanneschi, Universal bound on the eigen- values of 2-positive trace-preserving maps, Linear Alge- bra Its Appl.730, 262 (2026)
2026
-
[58]
Tang, On positive linear maps between matrix al- gebras, Linear Algebra Its Appl.79, 33 (1986)
W.-S. Tang, On positive linear maps between matrix al- gebras, Linear Algebra Its Appl.79, 33 (1986)
1986
-
[59]
Ha and S.-H
K.-C. Ha and S.-H. Kye, Construction of exposed inde- composable positive linear maps between matrix alge- bras, Linear Multilinear Algebra64, 2188 (2016)
2016
-
[60]
Christandl, A
M. Christandl, A. M¨ uller-Hermes, and M. M. Wolf, When do composed maps become entanglement breaking?, in Annales Henri Poincar´ e, Vol. 20 (Springer, 2019) pp. 2295–2322
2019
-
[61]
A. R. Morgillo and D. Poderini, incomplete positivity (2025). 11 0 50 100 150 200 250 300 epoch 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5loss =1.0 =0.005 =0.01 =0.02 =0.03 =0.05 =0.06 =0.09 0 50 100 150 200 250 300 epoch 0 1 2 3 4 5loss =1.5 =0.005 =0.01 =0.02 =0.03 =0.05 =0.06 =0.09 0 50 100 150 200 250 300 epoch 0 1 2 3 4 5 6 7loss =2.0 =0.005 =0.01 =0.02 =0.03 =...
2025
discussion (0)
Sign in with ORCID, Apple, or X to comment. Anyone can read and Pith papers without signing in.