On the structure of higher order quantum maps

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AbstractWe study higher order quantum maps in the context of a *-autonomous category of affine subspaces. We show that types of higher order maps can be identified with certain Boolean functions that we call type functions. By an extension of this identification, the algebraic structure of Boolean functions is inherited by some sets of quantum objects including higher order maps. Using the Mobius transform, we assign to each type function a poset whose elements are labelled by subsets of indices of the involved spaces. We then show that the type function corresponds to a comb type if and only if the poset is a chain. We also devise a procedure for decomposition of the poset to a set of basic chains from which the type function is constructed by taking maxima and minima of concatenations of the basic chains in different orders. On the level of higher order maps, maxima and minima correspond to affine mixtures and intersections, respectively.► BibTeX data@article{Jencova2026structureofhigher, doi = {10.22331/q-2026-05-05-2090}, url = {https://doi.org/10.22331/q-2026-05-05-2090}, title = {On the structure of higher order quantum maps}, author = {Jen{\v{c}}ov{\'{a}}, Anna}, journal = {{Quantum}}, issn = {2521-327X}, publisher = {{Verein zur F{\"{o}}rderung des Open Access Publizierens in den Quantenwissenschaften}}, volume = {10}, pages = {2090}, month = may, year = {2026} }► References [1] Luca Apadula, Alessandro Bisio, and Paolo Perinotti. ``No-signalling constrains quantum computation with indefinite causal structure''. Quantum 8, 1241 (2024). arXiv:2202.10214. https://doi.org/10.22331/q-2024-02-05-1241 arXiv:2202.10214 [2] G. Chiribella, G. M. D’Ariano, and P. Perinotti. ``Transforming quantum operations: Quantum supermaps''. EPL (Europhysics Letters) 83, 30004 (2008). arXiv:0804.0180. https://doi.org/10.1209/0295-5075/83/30004 arXiv:0804.0180 [3] 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:0712.1325 [4] Giulio Chiribella, Giacomo Mauro D'Ariano, and Paolo Perinotti. ``Theoretical framework for quantum networks''. Phys. Rev. A 80, 022339 (2009). arXiv:0904.4483. https://doi.org/10.1103/PhysRevA.80.022339 arXiv:0904.4483 [5] Gus Gutoski and John Watrous. ``Toward a general theory of quantum games''. In Proceedings of the thirty-ninth annual ACM symposium on Theory of computing. Page 565–574. STOC07. ACM (2007). arXiv:quant-ph/0611234. https://doi.org/10.1145/1250790.1250873 arXiv:quant-ph/0611234 [6] Giulio Chiribella, Giacomo M. D'Ariano, and Paolo Perinotti. ``Memory effects in quantum channel discrimination''. Phys. Rev. Lett. 101, 180501 (2008). arXiv:0803.3237. https://doi.org/10.1103/PhysRevLett.101.180501 arXiv:0803.3237 [7] Mário Ziman. ``Process positive-operator-valued measure: A mathematical framework for the description of process tomography experiments''. Phys. Rev. A 77, 062112 (2008). arXiv:0802.3862. https://doi.org/10.1103/PhysRevA.77.062112 arXiv:0802.3862 [8] Ognyan Oreshkov, Fabio Costa, and Časlav Brukner. ``Quantum correlations with no causal order''. Nature Communications 3, 1092 (2012). arXiv:1105.4464v3. https://doi.org/10.1038/ncomms2076 arXiv:1105.4464v3 [9] Giulio Chiribella, Giacomo Mauro D’Ariano, Paolo Perinotti, and Benoit Valiron. ``Quantum computations without definite causal structure''. Physical Review A 88, 022318 (2013). arXiv:0912.0195. https://doi.org/10.1103/PhysRevA.88.022318 arXiv:0912.0195 [10] Paolo Perinotti. ``Causal structures and the classification of higher order quantum computations''.
In Renato Renner and Sandra Stupar, editors, Time in Physics. Page 103–127.
Springer International Publishing (2017). arXiv:1612.05099. https://doi.org/10.1007/978-3-319-68655-4_7 arXiv:1612.05099 [11] Philip Taranto, Simon Milz, Mio Murao, Marco Túlio Quintino, and Kavan Modi. ``Higher-order quantum operations'' (2025). arXiv:2503.09693. arXiv:2503.09693 [12] Alessandro Bisio and Paolo Perinotti. ``Theoretical framework for higher-order quantum theory''. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 475, 20180706 (2019). arXiv:1806.09554. https://doi.org/10.1098/rspa.2018.0706 arXiv:1806.09554 [13] Aleks Kissinger and Sander Uijlen. ``A categorical semantics for causal structure''. Logical Methods in Computer Science 15 (2019). arXiv:1701.04732v6. https://doi.org/10.23638/LMCS-15(3:15)2019 arXiv:1701.04732v6 [14] Will Simmons and Aleks Kissinger. ``Higher-order causal theories are models of BV-logic''. In 47th International Symposium on Mathematical Foundations of Computer Science (MFCS 2022). Volume 241, page 80. (2022). arXiv:2205.11219. https://doi.org/10.4230/LIPIcs.MFCS.2022.80 arXiv:2205.11219 [15] Will Simmons and Aleks Kissinger. ``A complete logic for causal consistency'' (2024). arXiv:2403.09297. arXiv:2403.09297 [16] Timothée Hoffreumon and Ognyan Oreshkov. ``Projective characterization of higher-order quantum transformations''. Quantum 10, 1978 (2026). arXiv:2206.06206. https://doi.org/10.22331/q-2026-01-21-1978 arXiv:2206.06206 [17] Mateus Araújo, Cyril Branciard, Fabio Costa, Adrien Feix, Christina Giarmatzi, and Časlav Brukner. ``Witnessing causal nonseparability''. New Journal of Physics 17, 102001 (2015). arXiv:1506.03776. https://doi.org/10.1088/1367-2630/17/10/102001 arXiv:1506.03776 [18] Simon Milz and Marco Túlio Quintino. ``Characterising transformations between quantum objects, completeness of quantum properties, and transformations without a fixed causal order''. Quantum 8, 1415 (2024). arXiv:2305.01247. https://doi.org/10.22331/q-2024-07-17-1415 arXiv:2305.01247 [19] Julian Wechs, Hippolyte Dourdent, Alastair A. Abbott, and Cyril Branciard. ``Quantum circuits with classical versus quantum control of causal order''. PRX Quantum 2, 030335 (2021). arXiv:2101.08796. https://doi.org/10.1103/prxquantum.2.030335 arXiv:2101.08796 [20] Augustin Vanrietvelde, Nick Ormrod, Hlér Kristjánsson, and Jonathan Barrett. ``Consistent circuits for indefinite causal order''. Quantum 9, 1923 (2025). arXiv:2206.10042. https://doi.org/10.22331/q-2025-12-02-1923 arXiv:2206.10042 [21] Martin Plávala. ``General probabilistic theories: An introduction''. Physics Reports 1033, 1–64 (2023). arXiv:2103.07469. https://doi.org/10.1016/j.physrep.2023.09.001 arXiv:2103.07469 [22] Jessica Bavaresco, Amin Baumeler, Yelena Guryanova, and Costantino Budroni. ``Indefinite causal order in boxworld theories'' (2024). arXiv:2411.00951. arXiv:2411.00951 [23] Saunders Mac Lane. ``Categories for the working mathematician''. Volume 5. Springer Science & Business Media. (2013). https://doi.org/10.1007/978-1-4757-4721-8 [24] Kate Ponto and Michael Shulman. ``Traces in symmetric monoidal categories''. Expositiones Mathematicae 32, 248–273 (2014). arXiv:1107.6032. https://doi.org/10.1016/j.exmath.2013.12.003 arXiv:1107.6032 [25] Chris Heunen and Jamie Vicary. ``Categories for quantum theory: an introduction''.
Oxford University Press. (2019). https://doi.org/10.1093/oso/9780198739623.001.0001 [26] Michael Barr. ``*- autonomous categories''. Lecture Notes in Mathematics. Springer. Berlin, Heidelberg (1979). https://doi.org/10.1007/BFb0064579 [27] Gus Gutoski. ``Properties of local quantum operations with shared entanglement''. Quantum Information & Computation 9, 739–764 (2009). arXiv:0805.2209. https://doi.org/10.26421/qic9.9-10-2 arXiv:0805.2209 [28] Giulio Chiribella and Zixuan Liu. ``Quantum operations with indefinite time direction''. Communications Physics 5, 190 (2022). arXiv:2012.03859. https://doi.org/10.1038/s42005-022-00967-3 arXiv:2012.03859 [29] Simon Milz, Jessica Bavaresco, and Giulio Chiribella. ``Resource theory of causal connection''. Quantum 6, 788 (2022). arXiv:2110.03233. https://doi.org/10.22331/q-2022-08-25-788 arXiv:2110.03233 [30] Anna Jenčová. ``Order structure and signalling in higher order quantum maps'' (2026). arXiv:2604.09192. arXiv:2604.09192 [31] Ognyan Oreshkov and Christina Giarmatzi. ``Causal and causally separable processes''. New Journal of Physics 18, 093020 (2016). arXiv:1506.05449v3. https://doi.org/10.1088/1367-2630/18/9/093020 arXiv:1506.05449v3 [32] Amin Baumeler and Stefan Wolf. ``The space of logically consistent classical processes without causal order''. New Journal of Physics 18, 013036 (2016). arXiv:1507.01714. https://doi.org/10.1088/1367-2630/18/1/013036 arXiv:1507.01714 [33] Tom Leinster. ``Higher operads, higher categories''. Number 298 in London Mathematical Society Lecture Note Series.
Cambridge University Press. (2004). https://doi.org/10.1017/CBO9780511525896 [34] Richard P Stanley. ``Enumerative combinatorics, vol. 1''. Number 49 in Cambridge Studies in Advanced Mathematics.
Cambridge University Press. (2011). 2nd edition. https://doi.org/10.1017/CBO9781139058520Cited by[1] James Hefford and Matt Wilson, "A BV-Category of Spacetime Interventions", arXiv:2502.19022, (2025). [2] Anna Jenčová, "Order structure and signalling in higher order quantum maps", arXiv:2604.09192, (2026). [3] Matt Wilson, James Hefford, and Timothée Hoffreumon, "Supermaps on generalised theories", arXiv:2602.23865, (2026). [4] Matt Wilson and James Hefford, "Higher-Order Quantum Objects are Strong Profunctors", arXiv:2603.11221, (2026). [5] Matt Wilson, "Agent policies from higher-order causal functions", arXiv:2512.10937, (2025). The above citations are from SAO/NASA ADS (last updated successfully 2026-05-05 09:17:56). The list may be incomplete as not all publishers provide suitable and complete citation data.Could not fetch Crossref cited-by data during last attempt 2026-05-05 09:17:54: Could not fetch cited-by data for 10.22331/q-2026-05-05-2090 from Crossref. This is normal if the DOI was registered recently.This Paper is published in Quantum under the Creative Commons Attribution 4.0 International (CC BY 4.0) license. Copyright remains with the original copyright holders such as the authors or their institutions. AbstractWe study higher order quantum maps in the context of a *-autonomous category of affine subspaces. We show that types of higher order maps can be identified with certain Boolean functions that we call type functions. By an extension of this identification, the algebraic structure of Boolean functions is inherited by some sets of quantum objects including higher order maps. Using the Mobius transform, we assign to each type function a poset whose elements are labelled by subsets of indices of the involved spaces. We then show that the type function corresponds to a comb type if and only if the poset is a chain. We also devise a procedure for decomposition of the poset to a set of basic chains from which the type function is constructed by taking maxima and minima of concatenations of the basic chains in different orders. On the level of higher order maps, maxima and minima correspond to affine mixtures and intersections, respectively.► BibTeX data@article{Jencova2026structureofhigher, doi = {10.22331/q-2026-05-05-2090}, url = {https://doi.org/10.22331/q-2026-05-05-2090}, title = {On the structure of higher order quantum maps}, author = {Jen{\v{c}}ov{\'{a}}, Anna}, journal = {{Quantum}}, issn = {2521-327X}, publisher = {{Verein zur F{\"{o}}rderung des Open Access Publizierens in den Quantenwissenschaften}}, volume = {10}, pages = {2090}, month = may, year = {2026} }► References [1] Luca Apadula, Alessandro Bisio, and Paolo Perinotti. ``No-signalling constrains quantum computation with indefinite causal structure''. Quantum 8, 1241 (2024). arXiv:2202.10214. https://doi.org/10.22331/q-2024-02-05-1241 arXiv:2202.10214 [2] G. Chiribella, G. M. D’Ariano, and P. Perinotti. ``Transforming quantum operations: Quantum supermaps''. EPL (Europhysics Letters) 83, 30004 (2008). arXiv:0804.0180. https://doi.org/10.1209/0295-5075/83/30004 arXiv:0804.0180 [3] 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:0712.1325 [4] Giulio Chiribella, Giacomo Mauro D'Ariano, and Paolo Perinotti. ``Theoretical framework for quantum networks''. Phys. Rev. A 80, 022339 (2009). arXiv:0904.4483. https://doi.org/10.1103/PhysRevA.80.022339 arXiv:0904.4483 [5] Gus Gutoski and John Watrous. ``Toward a general theory of quantum games''. In Proceedings of the thirty-ninth annual ACM symposium on Theory of computing. Page 565–574. STOC07. ACM (2007). arXiv:quant-ph/0611234. https://doi.org/10.1145/1250790.1250873 arXiv:quant-ph/0611234 [6] Giulio Chiribella, Giacomo M. D'Ariano, and Paolo Perinotti. ``Memory effects in quantum channel discrimination''. Phys. Rev. Lett. 101, 180501 (2008). arXiv:0803.3237. https://doi.org/10.1103/PhysRevLett.101.180501 arXiv:0803.3237 [7] Mário Ziman. ``Process positive-operator-valued measure: A mathematical framework for the description of process tomography experiments''. Phys. Rev. A 77, 062112 (2008). arXiv:0802.3862. https://doi.org/10.1103/PhysRevA.77.062112 arXiv:0802.3862 [8] Ognyan Oreshkov, Fabio Costa, and Časlav Brukner. ``Quantum correlations with no causal order''. Nature Communications 3, 1092 (2012). arXiv:1105.4464v3. https://doi.org/10.1038/ncomms2076 arXiv:1105.4464v3 [9] Giulio Chiribella, Giacomo Mauro D’Ariano, Paolo Perinotti, and Benoit Valiron. ``Quantum computations without definite causal structure''. Physical Review A 88, 022318 (2013). arXiv:0912.0195. https://doi.org/10.1103/PhysRevA.88.022318 arXiv:0912.0195 [10] Paolo Perinotti. ``Causal structures and the classification of higher order quantum computations''.
In Renato Renner and Sandra Stupar, editors, Time in Physics. Page 103–127.
Springer International Publishing (2017). arXiv:1612.05099. https://doi.org/10.1007/978-3-319-68655-4_7 arXiv:1612.05099 [11] Philip Taranto, Simon Milz, Mio Murao, Marco Túlio Quintino, and Kavan Modi. ``Higher-order quantum operations'' (2025). arXiv:2503.09693. arXiv:2503.09693 [12] Alessandro Bisio and Paolo Perinotti. ``Theoretical framework for higher-order quantum theory''. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 475, 20180706 (2019). arXiv:1806.09554. https://doi.org/10.1098/rspa.2018.0706 arXiv:1806.09554 [13] Aleks Kissinger and Sander Uijlen. ``A categorical semantics for causal structure''. Logical Methods in Computer Science 15 (2019). arXiv:1701.04732v6. https://doi.org/10.23638/LMCS-15(3:15)2019 arXiv:1701.04732v6 [14] Will Simmons and Aleks Kissinger. ``Higher-order causal theories are models of BV-logic''. In 47th International Symposium on Mathematical Foundations of Computer Science (MFCS 2022). Volume 241, page 80. (2022). arXiv:2205.11219. https://doi.org/10.4230/LIPIcs.MFCS.2022.80 arXiv:2205.11219 [15] Will Simmons and Aleks Kissinger. ``A complete logic for causal consistency'' (2024). arXiv:2403.09297. arXiv:2403.09297 [16] Timothée Hoffreumon and Ognyan Oreshkov. ``Projective characterization of higher-order quantum transformations''. Quantum 10, 1978 (2026). arXiv:2206.06206. https://doi.org/10.22331/q-2026-01-21-1978 arXiv:2206.06206 [17] Mateus Araújo, Cyril Branciard, Fabio Costa, Adrien Feix, Christina Giarmatzi, and Časlav Brukner. ``Witnessing causal nonseparability''. New Journal of Physics 17, 102001 (2015). arXiv:1506.03776. https://doi.org/10.1088/1367-2630/17/10/102001 arXiv:1506.03776 [18] Simon Milz and Marco Túlio Quintino. ``Characterising transformations between quantum objects, completeness of quantum properties, and transformations without a fixed causal order''. Quantum 8, 1415 (2024). arXiv:2305.01247. https://doi.org/10.22331/q-2024-07-17-1415 arXiv:2305.01247 [19] Julian Wechs, Hippolyte Dourdent, Alastair A. Abbott, and Cyril Branciard. ``Quantum circuits with classical versus quantum control of causal order''. PRX Quantum 2, 030335 (2021). arXiv:2101.08796. https://doi.org/10.1103/prxquantum.2.030335 arXiv:2101.08796 [20] Augustin Vanrietvelde, Nick Ormrod, Hlér Kristjánsson, and Jonathan Barrett. ``Consistent circuits for indefinite causal order''. Quantum 9, 1923 (2025). arXiv:2206.10042. https://doi.org/10.22331/q-2025-12-02-1923 arXiv:2206.10042 [21] Martin Plávala. ``General probabilistic theories: An introduction''. Physics Reports 1033, 1–64 (2023). arXiv:2103.07469. https://doi.org/10.1016/j.physrep.2023.09.001 arXiv:2103.07469 [22] Jessica Bavaresco, Amin Baumeler, Yelena Guryanova, and Costantino Budroni. ``Indefinite causal order in boxworld theories'' (2024). arXiv:2411.00951. arXiv:2411.00951 [23] Saunders Mac Lane. ``Categories for the working mathematician''. Volume 5. Springer Science & Business Media. (2013). https://doi.org/10.1007/978-1-4757-4721-8 [24] Kate Ponto and Michael Shulman. ``Traces in symmetric monoidal categories''. Expositiones Mathematicae 32, 248–273 (2014). arXiv:1107.6032. https://doi.org/10.1016/j.exmath.2013.12.003 arXiv:1107.6032 [25] Chris Heunen and Jamie Vicary. ``Categories for quantum theory: an introduction''.
Oxford University Press. (2019). https://doi.org/10.1093/oso/9780198739623.001.0001 [26] Michael Barr. ``*- autonomous categories''. Lecture Notes in Mathematics. Springer. Berlin, Heidelberg (1979). https://doi.org/10.1007/BFb0064579 [27] Gus Gutoski. ``Properties of local quantum operations with shared entanglement''. Quantum Information & Computation 9, 739–764 (2009). arXiv:0805.2209. https://doi.org/10.26421/qic9.9-10-2 arXiv:0805.2209 [28] Giulio Chiribella and Zixuan Liu. ``Quantum operations with indefinite time direction''. Communications Physics 5, 190 (2022). arXiv:2012.03859. https://doi.org/10.1038/s42005-022-00967-3 arXiv:2012.03859 [29] Simon Milz, Jessica Bavaresco, and Giulio Chiribella. ``Resource theory of causal connection''. Quantum 6, 788 (2022). arXiv:2110.03233. https://doi.org/10.22331/q-2022-08-25-788 arXiv:2110.03233 [30] Anna Jenčová. ``Order structure and signalling in higher order quantum maps'' (2026). arXiv:2604.09192. arXiv:2604.09192 [31] Ognyan Oreshkov and Christina Giarmatzi. ``Causal and causally separable processes''. New Journal of Physics 18, 093020 (2016). arXiv:1506.05449v3. https://doi.org/10.1088/1367-2630/18/9/093020 arXiv:1506.05449v3 [32] Amin Baumeler and Stefan Wolf. ``The space of logically consistent classical processes without causal order''. New Journal of Physics 18, 013036 (2016). arXiv:1507.01714. https://doi.org/10.1088/1367-2630/18/1/013036 arXiv:1507.01714 [33] Tom Leinster. ``Higher operads, higher categories''. Number 298 in London Mathematical Society Lecture Note Series.
Cambridge University Press. (2004). https://doi.org/10.1017/CBO9780511525896 [34] Richard P Stanley. ``Enumerative combinatorics, vol. 1''. Number 49 in Cambridge Studies in Advanced Mathematics.
Cambridge University Press. (2011). 2nd edition. https://doi.org/10.1017/CBO9781139058520Cited by[1] James Hefford and Matt Wilson, "A BV-Category of Spacetime Interventions", arXiv:2502.19022, (2025). [2] Anna Jenčová, "Order structure and signalling in higher order quantum maps", arXiv:2604.09192, (2026). [3] Matt Wilson, James Hefford, and Timothée Hoffreumon, "Supermaps on generalised theories", arXiv:2602.23865, (2026). [4] Matt Wilson and James Hefford, "Higher-Order Quantum Objects are Strong Profunctors", arXiv:2603.11221, (2026). [5] Matt Wilson, "Agent policies from higher-order causal functions", arXiv:2512.10937, (2025). The above citations are from SAO/NASA ADS (last updated successfully 2026-05-05 09:17:56). The list may be incomplete as not all publishers provide suitable and complete citation data.Could not fetch Crossref cited-by data during last attempt 2026-05-05 09:17:54: Could not fetch cited-by data for 10.22331/q-2026-05-05-2090 from Crossref. This is normal if the DOI was registered recently.This Paper is published in Quantum under the Creative Commons Attribution 4.0 International (CC BY 4.0) license. Copyright remains with the original copyright holders such as the authors or their institutions.
