Characterising the Hierarchy of Multi-time Quantum Processes with Classical Memory

Philip Taranto1, Marco Túlio Quintino2, Mio Murao1, and Simon Milz3,4

1Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo City, Tokyo 113-0033, Japan
2Sorbonne Université, CNRS, LIP6, F-75005 Paris, France
3School of Physics, Trinity College Dublin, Dublin 2, Ireland
4Trinity Quantum Alliance, Unit 16, Trinity Technology and Enterprise Centre, Pearse Street, Dublin 2, D02YN67, Ireland

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Abstract

Memory is the fundamental form of temporal complexity: when present but uncontrollable, it manifests as non-Markovian noise; conversely, if controllable, memory can be a powerful resource for information processing. Memory effects arise from/are transmitted via interactions between a system and its environment; as such, they can be either classical or quantum. From a practical standpoint, quantum processes with classical memory promise near-term applicability: they are more powerful than their memoryless counterpart, yet at the same time can be controlled over significant timeframes without being spoiled by decoherence. However, despite practical and foundational value, apart from simple two-time scenarios, the distinction between quantum and classical memory remains unexplored. Here, we analyse multi-time quantum processes with memory mechanisms that transmit only classical information forward in time. Complementing this analysis, we also study two related – but simpler to characterise – sets of processes that could also be considered to have classical memory from a structural perspective, and demonstrate that these lead to remarkably distinct phenomena in the multi-time setting. Subsequently, we systematically stratify the full hierarchy of memory effects in quantum mechanics, many levels of which collapse in the two-time setting, making our results genuinely multi-time phenomena.

Talk presented at International Conference on Quantum Energy (Melbourne, 2023):

Memory plays a vital role in various natural and engineered processes, from predicting weather patterns to financial markets and computational tasks. When memory is present but uncontrollable, it leads to complex non-Markovian noise, which is challenging to model accurately. On the other hand, a controlled memory becomes a powerful tool for information processing, as seen in systems like quantum dots, where tunable memory can enhance properties like charge transport and emission spectra, potentially benefiting technologies like photovoltaic cells and communication protocols.

In the same vein as processes themselves, memory effects can be quantum or classical. They arise from interactions between a system of interest and its environment, with the latter acting as the memory carrier. Rapid dissipation of information leads to simple, memoryless processes; on the other hand, strong interactions with low dissipation often result in non-classical multi-time correlations. In between the two extremes of memorylessness and coherent quantum memory lies a class of quantum processes that offer significant application: quantum processes with classical memory. These are more powerful than memoryless ones and can be controlled over extended timeframes without being spoiled by decoherence or errors.

Despite their potential, understanding the distinction between quantum and classical memory has thus far remained largely unexplored. Here, we systematically characterise the hierarchy of multi-time memory effects in quantum mechanics, in particular demonstrating the distinct behaviour between various types of possible memory effects. Many levels of the engendered hierarchy only emerge as discernible beyond the two-time setting, making our results genuinely multi-time phenomena. On the practical side, since noise in quantum devices—and thus the observed memory effects—will predominately be classical in the near future, our work provides a methodological framework upon which efficient and reliable quantum devices can be built.

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► References

[1] N. van Kampen, Stochastic Processes in Physics and Chemistry (Elsevier, New York, 2011).

[2] C. Sayrin, I. Dotsenko, X. Zhou, B. Peaudecerf, T. Rybarczyk, S. Gleyzes, P. Rouchon, M. Mirrahimi, H. Amini, M. Brune, J.-M. Raimond, and S. Haroche, Real-time quantum feedback prepares and stabilizes photon number states, Nature 477, 73 (2011), arXiv:1107.4027.
https:/​/​doi.org/​10.1038/​nature10376
arXiv:arXiv:1107.4027

[3] L. Magrini, P. Rosenzweig, C. Bach, A. Deutschmann-Olek, S. G. Hofer, S. Hong, N. Kiesel, A. Kugi, and M. Aspelmeyer, Real-time optimal quantum control of mechanical motion at room temperature, Nature 595, 373 (2021), arXiv:2012.15188.
https:/​/​doi.org/​10.1038/​s41586-021-03602-3
arXiv:arXiv:2012.15188

[4] A. L. Grimsmo, Time-Delayed Quantum Feedback Control, Phys. Rev. Lett. 115, 060402 (2015), arXiv:1502.06959.
https:/​/​doi.org/​10.1103/​PhysRevLett.115.060402
arXiv:arXiv:1502.06959

[5] I. A. Luchnikov, S. V. Vintskevich, H. Ouerdane, and S. N. Filippov, Simulation Complexity of Open Quantum Dynamics: Connection with Tensor Networks, Phys. Rev. Lett. 122, 160401 (2019), arXiv:1812.00043.
https:/​/​doi.org/​10.1103/​PhysRevLett.122.160401
arXiv:arXiv:1812.00043

[6] M. R. Jørgensen and F. A. Pollock, Exploiting the Causal Tensor Network Structure of Quantum Processes to Efficiently Simulate Non-Markovian Path Integrals, Phys. Rev. Lett. 123, 240602 (2019), arXiv:1902.00315.
https:/​/​doi.org/​10.1103/​PhysRevLett.123.240602
arXiv:arXiv:1902.00315

[7] K. Banaszek, A. Dragan, W. Wasilewski, and C. Radzewicz, Experimental Demonstration of Entanglement-Enhanced Classical Communication over a Quantum Channel with Correlated Noise, Phys. Rev. Lett. 92, 257901 (2004), arXiv:quant-ph/​0403024.
https:/​/​doi.org/​10.1103/​PhysRevLett.92.257901
arXiv:arXiv:quant-ph/0403024

[8] J. Bavaresco, M. Murao, and M. T. Quintino, Strict Hierarchy between Parallel, Sequential, and Indefinite-Causal-Order Strategies for Channel Discrimination, Phys. Rev. Lett. 127, 200504 (2021), arXiv:2011.08300.
https:/​/​doi.org/​10.1103/​PhysRevLett.127.200504
arXiv:arXiv:2011.08300

[9] G. Chiribella, G. M. D'Ariano, and P. Perinotti, Quantum Circuit Architecture, Phys. Rev. Lett. 101, 060401 (2008), arXiv:0712.1325.
https:/​/​doi.org/​10.1103/​PhysRevLett.101.060401
arXiv:arXiv:0712.1325

[10] G. Chiribella, G. M. D'Ariano, and P. Perinotti, Theoretical framework for quantum networks, Phys. Rev. A 80, 022339 (2009), arXiv:0904.4483.
https:/​/​doi.org/​10.1103/​PhysRevA.80.022339
arXiv:arXiv:0904.4483

[11] S. Mavadia, C. L. Edmunds, C. Hempel, H. Ball, F. Roy, T. M. Stace, and M. J. Biercuk, Experimental quantum verification in the presence of temporally correlated noise, npj Quantum Inf. 4, 7 (2018), arXiv:1706.03787.
https:/​/​doi.org/​10.1038/​s41534-017-0052-0
arXiv:arXiv:1706.03787

[12] G. A. L. White, C. D. Hill, F. A. Pollock, L. C. L. Hollenberg, and K. Modi, Demonstration of non-Markovian process characterisation and control on a quantum processor, Nat. Commun. 11, 6301 (2020), arXiv:2004.14018.
https:/​/​doi.org/​10.1038/​s41467-020-20113-3
arXiv:arXiv:2004.14018

[13] A. Acín, I. Bloch, H. Buhrman, T. Calarco, C. Eichler, J. Eisert, D. Esteve, N. Gisin, S. J. Glaser, F. Jelezko, S. Kuhr, M. Lewenstein, M. F. Riedel, P. O. Schmidt, R. Thew, A. Wallraff, I. Walmsley, and F. K. Wilhelm, The quantum technologies roadmap: a European community view, New J. Phys. 20, 080201 (2018), arXiv:1712.03773.
https:/​/​doi.org/​10.1088/​1367-2630/​aad1ea
arXiv:arXiv:1712.03773

[14] L. Li, M. J. W. Hall, and H. M. Wiseman, Concepts of quantum non-Markovianity: A hierarchy, Phys. Rep. 759, 1 (2018), arXiv:1712.08879.
https:/​/​doi.org/​10.1016/​j.physrep.2018.07.001
arXiv:1712.08879

[15] P. Taranto, Memory Effects in Quantum Processes, Int. J. Quantum Inf. 18, 1941002 (2020), arXiv:1909.05245.
https:/​/​doi.org/​10.1142/​S0219749919410028
arXiv:1909.05245

[16] F. A. Pollock, C. Rodríguez-Rosario, T. Frauenheim, M. Paternostro, and K. Modi, Operational Markov Condition for Quantum Processes, Phys. Rev. Lett. 120, 040405 (2018a), arXiv:1801.09811.
https:/​/​doi.org/​10.1103/​PhysRevLett.120.040405
arXiv:arXiv:1801.09811

[17] F. A. Pollock, C. Rodríguez-Rosario, T. Frauenheim, M. Paternostro, and K. Modi, Non-Markovian quantum processes: Complete framework and efficient characterization, Phys. Rev. A 97, 012127 (2018b), arXiv:1512.00589.
https:/​/​doi.org/​10.1103/​PhysRevA.97.012127
arXiv:arXiv:1512.00589

[18] S. Milz, F. Sakuldee, F. A. Pollock, and K. Modi, Kolmogorov extension theorem for (quantum) causal modelling and general probabilistic theories, Quantum 4, 255 (2020a), arXiv:1712.02589.
https:/​/​doi.org/​10.22331/​q-2020-04-20-255
arXiv:arXiv:1712.02589

[19] P. Strasberg and M. G. Díaz, Classical quantum stochastic processes, Phys. Rev. A 100, 022120 (2019), arXiv:1905.03018.
https:/​/​doi.org/​10.1103/​PhysRevA.100.022120
arXiv:arXiv:1905.03018

[20] S. Milz, D. Egloff, P. Taranto, T. Theurer, M. B. Plenio, A. Smirne, and S. F. Huelga, When Is a Non-Markovian Quantum Process Classical? Phys. Rev. X 10, 041049 (2020b), arXiv:1907.05807.
https:/​/​doi.org/​10.1103/​PhysRevX.10.041049
arXiv:arXiv:1907.05807

[21] P. Taranto, F. A. Pollock, S. Milz, M. Tomamichel, and K. Modi, Quantum Markov Order, Phys. Rev. Lett. 122, 140401 (2019a), arXiv:1805.11341.
https:/​/​doi.org/​10.1103/​PhysRevLett.122.140401
arXiv:arXiv:1805.11341

[22] P. Taranto, S. Milz, F. A. Pollock, and K. Modi, Structure of quantum stochastic processes with finite Markov order, Phys. Rev. A 99, 042108 (2019b), arXiv:1810.10809.
https:/​/​doi.org/​10.1103/​PhysRevA.99.042108
arXiv:arXiv:1810.10809

[23] P. Taranto, F. A. Pollock, and K. Modi, Non-Markovian memory strength bounds quantum process recoverability, npj Quantum Inf. 7, 149 (2021), arXiv:1907.12583.
https:/​/​doi.org/​10.1038/​s41534-021-00481-4
arXiv:arXiv:1907.12583

[24] G. A. L. White, F. A. Pollock, L. C. L. Hollenberg, C. D. Hill, and K. Modi, From many-body to many-time physics, arXiv:2107.13934 (2021).
arXiv:2107.13934

[25] G. A. L. White, F. A. Pollock, L. C. L. Hollenberg, K. Modi, and C. D. Hill, Non-Markovian Quantum Process Tomography, PRX Quantum 3, 020344 (2022), arXiv:2106.11722.
https:/​/​doi.org/​10.1103/​PRXQuantum.3.020344
arXiv:arXiv:2106.11722

[26] Y. Guo, P. Taranto, B.-H. Liu, X.-M. Hu, Y.-F. Huang, C.-F. Li, and G.-C. Guo, Experimental Demonstration of Instrument-Specific Quantum Memory Effects and Non-Markovian Process Recovery for Common-Cause Processes, Phys. Rev. Lett. 126, 230401 (2021), arXiv:2003.14045.
https:/​/​doi.org/​10.1103/​PhysRevLett.126.230401
arXiv:arXiv:2003.14045

[27] D. Kretschmann and R. F. Werner, Quantum channels with memory, Phys. Rev. A 72, 062323 (2005), arXiv:quant-ph/​0502106.
https:/​/​doi.org/​10.1103/​PhysRevA.72.062323
arXiv:quant-ph/0502106

[28] G. Gutoski and J. Watrous, Toward a General Theory of Quantum Games, in Proceedings of the Thirty-Ninth Annual ACM Symposium on Theory of Computing, STOC '07 (Association for Computing Machinery, New York, NY, USA, 2007) p. 565, arXiv:quant-ph/​0611234.
https:/​/​doi.org/​10.1145/​1250790.1250873
arXiv:quant-ph/0611234

[29] O. Oreshkov, F. Costa, and Č. Brukner, Quantum correlations with no causal order, Nat. Commun. 3, 1092 (2012), arXiv:1105.4464.
https:/​/​doi.org/​10.1038/​ncomms2076
arXiv:1105.4464

[30] L. Hardy, The operator tensor formulation of quantum theory, Philos. Trans. Royal Soc. A 370, 3385 (2012), arXiv:1201.4390.
https:/​/​doi.org/​10.1098/​rsta.2011.0326
arXiv:1201.4390

[31] L. Hardy, Operational General Relativity: Possibilistic, Probabilistic, and Quantum, arXiv:1608.06940 (2016).
arXiv:1608.06940

[32] G. Lindblad, Non-Markovian quantum stochastic processes and their entropy, Commun. Math. Phys. 65, 281 (1979).
https:/​/​doi.org/​10.1007/​BF01197883

[33] L. Accardi, A. Frigerio, and J. T. Lewis, Quantum Stochastic Processes, Publ. Rest. Inst. Math. Sci. 18, 97 (1982).
https:/​/​doi.org/​10.2977/​prims/​1195184017

[34] R. Oeckl, A ``general boundary'' formulation for quantum mechanics and quantum gravity, Phys. Lett. B 575, 318 (2003), arXiv:hep-th/​0306025.
https:/​/​doi.org/​10.1016/​j.physletb.2003.08.043
arXiv:hep-th/0306025

[35] Y. Aharonov, S. Popescu, J. Tollaksen, and L. Vaidman, Multiple-time states and multiple-time measurements in quantum mechanics, Phys. Rev. A 79, 052110 (2009), arXiv:0712.0320.
https:/​/​doi.org/​10.1103/​PhysRevA.79.052110
arXiv:0712.0320

[36] J. Cotler and F. Wilczek, Entangled histories, Phys. Scr. 2016, 014004 (2016), arXiv:1502.02480.
https:/​/​doi.org/​10.1088/​0031-8949/​2016/​T168/​014004
arXiv:1502.02480

[37] C. Portmann, C. Matt, U. Mauerer, R. Renner, and B. Tackmann, Causal Boxes: Quantum Information-Processing Systems Closed under Composition, IEEE Trans. Inf. Theory 65, 3277 (2017), arXiv:1512.02240.
https:/​/​doi.org/​10.1109/​TIT.2017.2676805
arXiv:1512.02240

[38] G. D. Berk, A. J. P. Garner, B. Yadin, K. Modi, and F. A. Pollock, Resource theories of multi-time processes: A window into quantum non-Markovianity, Quantum 5, 435 (2021a), arXiv:1907.07003.
https:/​/​doi.org/​10.22331/​q-2021-04-20-435
arXiv:1907.07003

[39] G. D. Berk, S. Milz, F. A. Pollock, and K. Modi, Extracting Quantum Dynamical Resources: Consumption of Non-Markovianity for Noise Reduction, arXiv:2110.02613 (2021b).
arXiv:2110.02613

[40] C. Giarmatzi and F. Costa, Witnessing quantum memory in non-Markovian processes, Quantum 5, 440 (2021), arXiv:1811.03722.
https:/​/​doi.org/​10.22331/​q-2021-04-26-440
arXiv:arXiv:1811.03722

[41] M. Nery, M. T. Quintino, P. A. Guérin, T. O. Maciel, and R. O. Vianna, Simple and maximally robust processes with no classical common-cause or direct-cause explanation, Quantum 5, 538 (2021), arXiv:2101.11630.
https:/​/​doi.org/​10.22331/​q-2021-09-09-538
arXiv:arXiv:2101.11630

[42] N. van Kampen, Remarks on Non-Markov Processes, Braz. J. Phys. 28, 90 (1998).
https:/​/​doi.org/​10.1590/​S0103-97331998000200003

[43] R. Horodecki, P. Horodecki, M. Horodecki, and K. Horodecki, Quantum entanglement, Rev. Mod. Phys. 81, 865 (2009), arXiv:quant-ph/​0702225.
https:/​/​doi.org/​10.1103/​RevModPhys.81.865
arXiv:quant-ph/0702225

[44] A. Jamiołkowski, Linear transformations which preserve trace and positive semidefiniteness of operators, Rep. Math. Phys. 3, 275 (1972).
https:/​/​doi.org/​10.1016/​0034-4877(72)90011-0

[45] M.-D. Choi, Completely positive linear maps on complex matrices, Linear Algebra Its Appl. 10, 285 (1975).
https:/​/​doi.org/​10.1016/​0024-3795(75)90075-0

[46] A. A. Budini, Quantum Non-Markovian Processes Break Conditional Past-Future Independence, Phys. Rev. Lett. 121, 240401 (2018), arXiv:1811.03448.
https:/​/​doi.org/​10.1103/​PhysRevLett.121.240401
arXiv:arXiv:1811.03448

[47] A. A. Budini, Quantum Non-Markovian Environment-to-System Backflows of Information: Nonoperational vs. Operational Approaches, Entropy 24, 649 (2022), arXiv:2205.03333.
https:/​/​doi.org/​10.3390/​e24050649
arXiv:arXiv:2205.03333

[48] P. Strasberg, A. Winter, J. Gemmer, and J. Wang, Classicality, Markovianity, and local detailed balance from pure-state dynamics, Phys. Rev. A 108, 012225 (2023), arXiv:2209.07977.
https:/​/​doi.org/​10.1103/​PhysRevA.108.012225
arXiv:2209.07977

[49] P. Taranto, T. J. Elliott, and S. Milz, Hidden Quantum Memory: Is Memory There When Somebody Looks? Quantum 7, 991 (2023), arXiv:2204.08298.
https:/​/​doi.org/​10.22331/​q-2023-04-27-991
arXiv:arXiv:2204.08298

[50] M. Horodecki, P. W. Shor, and M. B. Ruskai, Entanglement Breaking Channels, Rev. Math. Phys. 15, 629 (2003), arXiv:quant-ph/​0302031.
https:/​/​doi.org/​10.1142/​S0129055X03001709
arXiv:arXiv:quant-ph/0302031

[51] N. Brunner, D. Cavalcanti, S. Pironio, V. Scarani, and S. Wehner, Bell nonlocality, Rev. Mod. Phys. 86, 419 (2014), arXiv:1303.2849.
https:/​/​doi.org/​10.1103/​RevModPhys.86.419
arXiv:arXiv:1303.2849

[52] V. Gorini, A. Kossakowski, and E. C. G. Sudarshan, Completely positive dynamical semigroups of N‐level systems, J. Math. Phys. 17, 821 (1976).
https:/​/​doi.org/​10.1063/​1.522979

[53] G. Lindblad, On the generators of quantum dynamical semigroups, Commun. Math. Phys. 48, 119 (1976).
https:/​/​doi.org/​10.1007/​BF01608499

[54] F. Costa and S. Shrapnel, Quantum causal modelling, New J. Phys. 18, 063032 (2016), arXiv:1512.07106.
https:/​/​doi.org/​10.1088/​1367-2630/​18/​6/​063032
arXiv:arXiv:1512.07106

[55] K. Ried, M. Agnew, L. Vermeyden, D. Janzing, R. W. Spekkens, and K. J. Resch, A quantum advantage for inferring causal structure, Nat. Phys. 11, 414 (2015), arXiv:1406.5036.
https:/​/​doi.org/​10.1038/​nphys3266
arXiv:1406.5036

[56] A. Feix and Č. Brukner, Quantum superpositions of `common-cause' and `direct-cause' causal structures, New J. Phys. 19, 123028 (2017), arXiv:1606.09241.
https:/​/​doi.org/​10.1088/​1367-2630/​aa9b1a
arXiv:arXiv:1606.09241

[57] E. M. Rains, Entanglement purification via separable superoperators, arXiv:quant-ph/​9707002 (1997).
arXiv:quant-ph/9707002

[58] V. Vedral, M. B. Plenio, M. A. Rippin, and P. L. Knight, Quantifying Entanglement, Phys. Rev. Lett. 78, 2275 (1997), arXiv:quant-ph/​9702027.
https:/​/​doi.org/​10.1103/​PhysRevLett.78.2275
arXiv:quant-ph/9702027

[59] C. H. Bennett, D. P. DiVincenzo, C. A. Fuchs, T. Mor, E. Rains, P. W. Shor, J. A. Smolin, and W. K. Wootters, Quantum nonlocality without entanglement, Phys. Rev. A 59, 1070 (1999), arXiv:quant-ph/​9804053.
https:/​/​doi.org/​10.1103/​PhysRevA.59.1070
arXiv:quant-ph/9804053

[60] S. Milz, C. Spee, Z.-P. Xu, F. A. Pollock, K. Modi, and O. Gühne, Genuine multipartite entanglement in time, SciPost Phys. 10, 141 (2021), arXiv:2011.09340.
https:/​/​doi.org/​10.21468/​SciPostPhys.10.6.141
arXiv:arXiv:2011.09340

[61] D. Beckman, D. Gottesman, M. A. Nielsen, and J. Preskill, Causal and localizable quantum operations, Phys. Rev. A 64, 052309 (2001), arXiv:quant-ph/​0102043.
https:/​/​doi.org/​10.1103/​PhysRevA.64.052309
arXiv:arXiv:quant-ph/0102043

[62] M. Piani, M. Horodecki, P. Horodecki, and R. Horodecki, Properties of quantum nonsignaling boxes, Phys. Rev. A 74, 012305 (2006), arXiv:quant-ph/​0505110.
https:/​/​doi.org/​10.1103/​PhysRevA.74.012305
arXiv:arXiv:quant-ph/0505110

[63] A. Peres, Separability Criterion for Density Matrices, Phys. Rev. Lett. 77, 1413 (1996), arXiv:quant-ph/​9604005.
https:/​/​doi.org/​10.1103/​PhysRevLett.77.1413
arXiv:quant-ph/9604005

[64] M. Horodecki, P. Horodecki, and R. Horodecki, Separability of mixed states: necessary and sufficient conditions, Phys. Lett. A 223, 1 (1996), arXiv:quant-ph/​9605038.
https:/​/​doi.org/​10.1016/​S0375-9601(96)00706-2
arXiv:quant-ph/9605038

[65] O. Gühne and G. Tóth, Entanglement detection, Phys. Rep. 474, 1 (2009), arXiv:0811.2803.
https:/​/​doi.org/​10.1016/​j.physrep.2009.02.004
arXiv:0811.2803

[66] A. C. Doherty, P. A. Parrilo, and F. M. Spedalieri, Complete family of separability criteria, Phys. Rev. A 69, 022308 (2004), arXiv:quant-ph/​0308032.
https:/​/​doi.org/​10.1103/​PhysRevA.69.022308
arXiv:quant-ph/0308032

[67] V. Vedral and M. B. Plenio, Entanglement measures and purification procedures, Phys. Rev. A 57, 1619 (1998).
https:/​/​doi.org/​10.1103/​PhysRevA.57.1619

[68] A. Bisio, G. Chiribella, G. M. D'Ariano, and P. Perinotti, Quantum Networks: general theory and applications, Acta Phys. Slovaca 61, 273 (2011), arXiv:1601.04864.
https:/​/​doi.org/​10.2478/​v10155-011-0003-9
arXiv:1601.04864
http:/​/​www.physics.sk/​aps/​pub.php?y=2011&pub=aps-11-03

[69] G. Chiribella and D. Ebler, Optimal quantum networks and one-shot entropies, New J. Phys. 18, 093053 (2016), arXiv:1606.02394.
https:/​/​doi.org/​10.1088/​1367-2630/​18/​9/​093053
arXiv:1606.02394

[70] P. Skrzypczyk and D. Cavalcanti, Semidefinite Programming in Quantum Information Science (IOP Publishing, Bristol, UK, 2023) arXiv:2306.11637.
https:/​/​doi.org/​10.1088/​978-0-7503-3343-6
arXiv:2306.11637

[71] L. Gurvits, Classical deterministic complexity of Edmonds' problem and quantum entanglement, in Proceedings of the thirty-fifth annual ACM symposium on Theory of computing (2003) pp. 10–19, arXiv:quant-ph/​0303055.
https:/​/​doi.org/​10.1145/​780542.780545
arXiv:quant-ph/0303055

[72] T.-A. Ohst, X.-D. Yu, O. Gühne, and H. Chau Nguyen, Certifying quantum separability with adaptive polytopes, SciPost Phys. 16, 063 (2024), arXiv:2011.09340.
https:/​/​doi.org/​10.21468/​SciPostPhys.16.3.063
arXiv:arXiv:2011.09340

[73] W. F. Stinespring, Positive functions on $C^{\ast}$-algebras, Proc. Amer. Math. Soc. 6, 211 (1955).
https:/​/​doi.org/​10.1090/​S0002-9939-1955-0069403-4

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