##### Leader of the research group: Paweł Horodecki

Post-doc: Piotr Mironowicz, Borhan Ahmadi, Some Sankar Bhattacharya, Nitica Sakharwade

PhD students: Ricard Ravell, Sumit Rout

The broad aim of the New Quantum Resources Group would be to perform research concerning quantum phenomena which could be used for quantum information processing.

## Activity

Examples of possible initial specific topics are:

– Connections between quantum computational speedup and contextuality/Bell-“nonlocality”

– New protocols on randomness amplification

– Research on communication networks

– Connections between violations of Bell inequalities and of non-contextuality and the quantum

advantage in communication complexity

– Quantum thermodynamics with state transitions by Thermal Operations.

– Relativistic quantum information processing

## Publications

### 2021

- Tomasz Miller, Michał Eckstein, Paweł Horodecki, and Ryszard Horodecki. Generally covariant N -particle dynamics.
*Journal of Geometry and Physics*, 160:103990, feb 2021. doi:10.1016/j.geomphys.2020.103990

[BibTeX] [Download PDF]`@Article{miller_generally_2021, author = {Miller, Tomasz and Eckstein, Michał and Horodecki, Paweł and Horodecki, Ryszard}, journal = {Journal of {G}eometry and {P}hysics}, title = {Generally covariant {N} -particle dynamics}, year = {2021}, issn = {03930440}, month = feb, pages = {103990}, volume = {160}, doi = {10.1016/j.geomphys.2020.103990}, groups = {Pawel_H, Michal_H}, language = {en}, url = {https://linkinghub.elsevier.com/retrieve/pii/S0393044020302539}, urldate = {2021-05-10}, }`

- B. Ahmadi, S. Salimi, and A. S. Khorashad. Irreversible work and Maxwell demon in terms of quantum thermodynamic force.
*Scientific Reports*, 11(1):2301, dec 2021. doi:10.1038/s41598-021-81737-z

[BibTeX] [Abstract] [Download PDF]

Abstract The second law of classical equilibrium thermodynamics, based on the positivity of entropy production, asserts that any process occurs only in a direction that some information may be lost (flow out of the system) due to the irreversibility inside the system. However, any thermodynamic system can exhibit fluctuations in which negative entropy production may be observed. In particular, in stochastic quantum processes due to quantum correlations and also memory effects we may see the reversal energy flow (heat flow from the cold system to the hot system) and the backflow of information into the system that leads to the negativity of the entropy production which is an apparent violation of the Second Law. In order to resolve this apparent violation, we will try to properly extend the Second Law to quantum processes by incorporating information explicitly into the Second Law. We will also provide a thermodynamic operational meaning for the flow and backflow of information. Finally, it is shown that negative and positive entropy production can be described by a quantum thermodynamic force.

`@Article{ahmadi_irreversible_2021, author = {Ahmadi, B. and Salimi, S. and Khorashad, A. S.}, journal = {Scientific {R}eports}, title = {Irreversible work and {Maxwell} demon in terms of quantum thermodynamic force}, year = {2021}, issn = {2045-2322}, month = dec, number = {1}, pages = {2301}, volume = {11}, abstract = {Abstract The second law of classical equilibrium thermodynamics, based on the positivity of entropy production, asserts that any process occurs only in a direction that some information may be lost (flow out of the system) due to the irreversibility inside the system. However, any thermodynamic system can exhibit fluctuations in which negative entropy production may be observed. In particular, in stochastic quantum processes due to quantum correlations and also memory effects we may see the reversal energy flow (heat flow from the cold system to the hot system) and the backflow of information into the system that leads to the negativity of the entropy production which is an apparent violation of the Second Law. In order to resolve this apparent violation, we will try to properly extend the Second Law to quantum processes by incorporating information explicitly into the Second Law. We will also provide a thermodynamic operational meaning for the flow and backflow of information. Finally, it is shown that negative and positive entropy production can be described by a quantum thermodynamic force.}, doi = {10.1038/s41598-021-81737-z}, language = {en}, url = {http://www.nature.com/articles/s41598-021-81737-z}, urldate = {2021-05-10}, }`

- Piotr Mironowicz, Gustavo Cañas, Jaime Cariñe, Esteban S. Gómez, Johanna F. Barra, Adán Cabello, Guilherme B. Xavier, Gustavo Lima, and Marcin Pawłowski. Quantum randomness protected against detection loophole attacks.
*Quantum Information Processing*, 20(1):39, jan 2021. doi:10.1007/s11128-020-02948-3

[BibTeX] [Download PDF]`@Article{mironowicz_quantum_2021, author = {Mironowicz, Piotr and Cañas, Gustavo and Cariñe, Jaime and Gómez, Esteban S. and Barra, Johanna F. and Cabello, Adán and Xavier, Guilherme B. and Lima, Gustavo and Pawłowski, Marcin}, journal = {Quantum {I}nformation {P}rocessing}, title = {Quantum randomness protected against detection loophole attacks}, year = {2021}, issn = {1570-0755, 1573-1332}, month = jan, number = {1}, pages = {39}, volume = {20}, doi = {10.1007/s11128-020-02948-3}, language = {en}, url = {http://link.springer.com/10.1007/s11128-020-02948-3}, urldate = {2021-05-10}, }`

- Roberto Salazar, Tanmoy Biswas, Jakub Czartowski, Karol Życzkowski, and Paweł Horodecki. Optimal allocation of quantum resources.
*Quantum*, 5:407, mar 2021. doi:10.22331/q-2021-03-10-407

[BibTeX] [Abstract] [Download PDF]

The optimal allocation of resources is a crucial task for their efficient use in a wide range of practical applications in science and engineering. This paper investigates the optimal allocation of resources in multipartite quantum systems. In particular, we show the relevance of proportional fairness and optimal reliability criteria for the application of quantum resources. Moreover, we present optimal allocation solutions for an arbitrary number of qudits using measurement incompatibility as an exemplary resource theory. Besides, we study the criterion of optimal equitability and demonstrate its relevance to scenarios involving several resource theories such as nonlocality vs local contextuality. Finally, we highlight the potential impact of our results for quantum networks and other multi-party quantum information processing, in particular to the future Quantum Internet.

`@Article{salazar_optimal_2021, author = {Salazar, Roberto and Biswas, Tanmoy and Czartowski, Jakub and Życzkowski, Karol and Horodecki, Paweł}, journal = {Quantum}, title = {Optimal allocation of quantum resources}, year = {2021}, issn = {2521-327X}, month = mar, pages = {407}, volume = {5}, abstract = {The optimal allocation of resources is a crucial task for their efficient use in a wide range of practical applications in science and engineering. This paper investigates the optimal allocation of resources in multipartite quantum systems. In particular, we show the relevance of proportional fairness and optimal reliability criteria for the application of quantum resources. Moreover, we present optimal allocation solutions for an arbitrary number of qudits using measurement incompatibility as an exemplary resource theory. Besides, we study the criterion of optimal equitability and demonstrate its relevance to scenarios involving several resource theories such as nonlocality vs local contextuality. Finally, we highlight the potential impact of our results for quantum networks and other multi-party quantum information processing, in particular to the future Quantum Internet.}, doi = {10.22331/q-2021-03-10-407}, groups = {Pawel_H}, language = {en}, url = {https://quantum-journal.org/papers/q-2021-03-10-407/}, urldate = {2021-07-28}, }`

- Michał Banacki, Ricard Ravell Rodríguez, and Paweł Horodecki. On the edge of the set of no-signaling assemblages.
*Physical Review A*, 103(5):52434, may 2021. arXiv: 2008.12325 doi:10.1103/PhysRevA.103.052434

[BibTeX] [Abstract] [Download PDF]

Following recent advancements, we consider a scenario of multipartite postquantum steering and general no-signaling assemblages. We introduce the notion of the edge of the set of no-signaling assemblages and we present its characterization. Next, we use this concept to construct witnesses for no-signaling assemblages without an LHS model. Finally, in the simplest nontrivial case of steering with two untrusted subsystems, we discuss the possibility of quantum realization of assemblages on the edge. In particular, for three-qubit states, we obtain a no-go type result, which states that it is impossible to produce assemblage on the edge using measurements described by POVMs as long as the rank of a given state is greater than or equal to 3.

`@Article{banacki_edge_2021, author = {Banacki, Michał and Rodríguez, Ricard Ravell and Horodecki, Paweł}, journal = {Physical {R}eview {A}}, title = {On the edge of the set of no-signaling assemblages}, year = {2021}, issn = {2469-9926, 2469-9934}, month = may, note = {arXiv: 2008.12325}, number = {5}, pages = {052434}, volume = {103}, abstract = {Following recent advancements, we consider a scenario of multipartite postquantum steering and general no-signaling assemblages. We introduce the notion of the edge of the set of no-signaling assemblages and we present its characterization. Next, we use this concept to construct witnesses for no-signaling assemblages without an LHS model. Finally, in the simplest nontrivial case of steering with two untrusted subsystems, we discuss the possibility of quantum realization of assemblages on the edge. In particular, for three-qubit states, we obtain a no-go type result, which states that it is impossible to produce assemblage on the edge using measurements described by POVMs as long as the rank of a given state is greater than or equal to 3.}, doi = {10.1103/PhysRevA.103.052434}, groups = {Pawel_H}, keywords = {Quantum Physics}, url = {http://arxiv.org/abs/2008.12325}, urldate = {2021-07-28}, }`

- Erik Aurell, Michał Eckstein, and Paweł Horodecki. Quantum Black Holes as Solvents.
*Foundations of Physics*, 51(2):54, apr 2021. doi:10.1007/s10701-021-00456-7

[BibTeX] [Abstract] [Download PDF]

Abstract Almost all of the entropy in the universe is in the form of Bekenstein–Hawking (BH) entropy of super-massive black holes. This entropy, if it satisfies Boltzmann’s equation \$\$S={\textbackslash}log {\textbackslash}mathcal\{N\}\$\$ S = log N , hence represents almost all the accessible phase space of the Universe, somehow associated to objects which themselves fill out a very small fraction of ordinary three-dimensional space. Although time scales are very long, it is believed that black holes will eventually evaporate by emitting Hawking radiation, which is thermal when counted mode by mode. A pure quantum state collapsing to a black hole will hence eventually re-emerge as a state with strictly positive entropy, which constitutes the famous black hole information paradox. Expanding on a remark by Hawking we posit that BH entropy is a thermodynamic entropy, which must be distinguished from information-theoretic entropy. The paradox can then be explained by information return in Hawking radiation. The novel perspective advanced here is that if BH entropy counts the number of accessible physical states in a quantum black hole, then the paradox can be seen as an instance of the fundamental problem of statistical mechanics. We suggest a specific analogy to the increase of the entropy in a solvation process. We further show that the huge phase volume ( \$\${\textbackslash}mathcal\{N\}\$\$ N ), which must be made available to the universe in a gravitational collapse, cannot originate from the entanglement between ordinary matter and/or radiation inside and outside the black hole. We argue that, instead, the quantum degrees of freedom of the gravitational field must get activated near the singularity, resulting in a final state of the ‘entangled entanglement’ form involving both matter and gravity.

`@Article{Aurell2021, author = {Aurell, Erik and Eckstein, Michał and Horodecki, Paweł}, journal = {Foundations of {P}hysics}, title = {Quantum {Black} {Holes} as {Solvents}}, year = {2021}, issn = {0015-9018, 1572-9516}, month = apr, number = {2}, pages = {54}, volume = {51}, abstract = {Abstract Almost all of the entropy in the universe is in the form of Bekenstein–Hawking (BH) entropy of super-massive black holes. This entropy, if it satisfies Boltzmann’s equation \$\$S={\textbackslash}log {\textbackslash}mathcal\{N\}\$\$ S = log N , hence represents almost all the accessible phase space of the Universe, somehow associated to objects which themselves fill out a very small fraction of ordinary three-dimensional space. Although time scales are very long, it is believed that black holes will eventually evaporate by emitting Hawking radiation, which is thermal when counted mode by mode. A pure quantum state collapsing to a black hole will hence eventually re-emerge as a state with strictly positive entropy, which constitutes the famous black hole information paradox. Expanding on a remark by Hawking we posit that BH entropy is a thermodynamic entropy, which must be distinguished from information-theoretic entropy. The paradox can then be explained by information return in Hawking radiation. The novel perspective advanced here is that if BH entropy counts the number of accessible physical states in a quantum black hole, then the paradox can be seen as an instance of the fundamental problem of statistical mechanics. We suggest a specific analogy to the increase of the entropy in a solvation process. We further show that the huge phase volume ( \$\${\textbackslash}mathcal\{N\}\$\$ N ), which must be made available to the universe in a gravitational collapse, cannot originate from the entanglement between ordinary matter and/or radiation inside and outside the black hole. We argue that, instead, the quantum degrees of freedom of the gravitational field must get activated near the singularity, resulting in a final state of the ‘entangled entanglement’ form involving both matter and gravity.}, doi = {10.1007/s10701-021-00456-7}, groups = {Pawel_H}, language = {en}, url = {https://link.springer.com/10.1007/s10701-021-00456-7}, urldate = {2021-10-11}, }`

- Carlo Maria Scandolo, Roberto Salazar, Jarosław K. Korbicz, and Paweł Horodecki. Universal structure of objective states in all fundamental causal theories.
*Physical Review Research*, 3(3):33148, aug 2021. doi:10.1103/PhysRevResearch.3.033148

[BibTeX] [Abstract] [Download PDF]

A crucial question is how objective and classical behavior arises from a fundamental physical theory. Here we provide a natural definition of a decoherence process valid in all causal theories and show how its behavior can be extremely different from the quantum one. Remarkably, despite this, we prove that the so- called spectrum broadcast structure characterizes all objective states in every fundamental causal theory, exactly as in quantum mechanics. Our results show a stark contrast between the extraordinarily diverse decoherence behavior and the universal features of objectivity.

`@Article{Scandolo2021, author = {Scandolo, Carlo Maria and Salazar, Roberto and Korbicz, Jarosław K. and Horodecki, Paweł}, journal = {Physical {R}eview {R}esearch}, title = {Universal structure of objective states in all fundamental causal theories}, year = {2021}, month = aug, number = {3}, pages = {033148}, volume = {3}, abstract = {A crucial question is how objective and classical behavior arises from a fundamental physical theory. Here we provide a natural definition of a decoherence process valid in all causal theories and show how its behavior can be extremely different from the quantum one. Remarkably, despite this, we prove that the so- called spectrum broadcast structure characterizes all objective states in every fundamental causal theory, exactly as in quantum mechanics. Our results show a stark contrast between the extraordinarily diverse decoherence behavior and the universal features of objectivity.}, doi = {10.1103/PhysRevResearch.3.033148}, eid = {033148}, groups = {Pawel_H}, url = {https://ui.adsabs.harvard.edu/abs/2021PhRvR...3c3148S}, }`

- Tamal Guha, Mir Alimuddin, Sumit Rout, Amit Mukherjee, Some Sankar Bhattacharya, and Manik Banik. Quantum advantage for shared randomness generation.
*Quantum*, 5:569, 2021. doi:10.22331/q-2021-10-27-569

[BibTeX] [Download PDF]`@Article{Guha2021, author = {Guha, Tamal and Alimuddin, Mir and Rout, Sumit and Mukherjee, Amit and Bhattacharya, Some Sankar and Banik, Manik}, journal = {Quantum}, title = {Quantum Advantage for Shared Randomness Generation}, year = {2021}, pages = {569}, volume = {5}, archiveprefix = {arXiv}, doi = {10.22331/q-2021-10-27-569}, eprint = {2001.01889}, primaryclass = {quant-ph}, url = {https://quantum-journal.org/papers/q-2021-10-27-569/pdf/}, }`

### 2020

- Massimiliano Smania, Piotr Mironowicz, Mohamed Nawareg, Marcin Pawłowski, Adán Cabello, and Mohamed Bourennane. Experimental certification of an informationally complete quantum measurement in a device-independent protocol.
*Optica*, 7(2):123, feb 2020. doi:10.1364/OPTICA.377959

[BibTeX] [Download PDF]`@article{smania_experimental_2020, title = {Experimental certification of an informationally complete quantum measurement in a device-independent protocol}, volume = {7}, issn = {2334-2536}, url = {https://www.osapublishing.org/abstract.cfm?URI=optica-7-2-123}, doi = {10.1364/OPTICA.377959}, language = {en}, number = {2}, urldate = {2020-04-22}, journal = {Optica}, author = {Smania, Massimiliano and Mironowicz, Piotr and Nawareg, Mohamed and Pawłowski, Marcin and Cabello, Adán and Bourennane, Mohamed}, month = feb, year = {2020}, pages = {123}, }`

- Géza Tóth, Tamás Vértesi, Paweł Horodecki, and Ryszard Horodecki. Activating Hidden Metrological Usefulness.
*Physical Review Letters*, 125(2):20402, jul 2020. doi:10.1103/PhysRevLett.125.020402

[BibTeX] [Download PDF]`@Article{toth_activating_2020, author = {Tóth, Géza and Vértesi, Tamás and Horodecki, Paweł and Horodecki, Ryszard}, journal = {Physical {R}eview {L}etters}, title = {Activating {Hidden} {Metrological} {Usefulness}}, year = {2020}, issn = {0031-9007, 1079-7114}, month = jul, number = {2}, pages = {020402}, volume = {125}, doi = {10.1103/PhysRevLett.125.020402}, groups = {Pawel_H}, language = {en}, url = {https://link.aps.org/doi/10.1103/PhysRevLett.125.020402}, urldate = {2021-05-10}, }`

- Ravishankar Ramanathan, Monika Rosicka, Karol Horodecki, Stefano Pironio, Michał Horodecki, and Paweł Horodecki. Gadget structures in proofs of the Kochen-Specker theorem.
*Quantum*, 4:308, aug 2020. doi:10.22331/q-2020-08-14-308

[BibTeX] [Abstract] [Download PDF]

The Kochen-Specker theorem is a fundamental result in quantum foundations that has spawned massive interest since its inception. We show that within every Kochen-Specker graph, there exist interesting subgraphs which we term 01 -gadgets, that capture the essential contradiction necessary to prove the Kochen-Specker theorem, i.e,. every Kochen-Specker graph contains a 01 -gadget and from every 01 -gadget one can construct a proof of the Kochen-Specker theorem. Moreover, we show that the 01 -gadgets form a fundamental primitive that can be used to formulate state-independent and state-dependent statistical Kochen-Specker arguments as well as to give simple constructive proofs of an “extended” Kochen-Specker theorem first considered by Pitowsky in {\textbackslash}cite\{Pitowsky\}.

`@Article{ramanathan_gadget_2020, author = {Ramanathan, Ravishankar and Rosicka, Monika and Horodecki, Karol and Pironio, Stefano and Horodecki, Michał and Horodecki, Paweł}, journal = {Quantum}, title = {Gadget structures in proofs of the {Kochen}-{Specker} theorem}, year = {2020}, issn = {2521-327X}, month = aug, pages = {308}, volume = {4}, abstract = {The Kochen-Specker theorem is a fundamental result in quantum foundations that has spawned massive interest since its inception. We show that within every Kochen-Specker graph, there exist interesting subgraphs which we term 01 -gadgets, that capture the essential contradiction necessary to prove the Kochen-Specker theorem, i.e,. every Kochen-Specker graph contains a 01 -gadget and from every 01 -gadget one can construct a proof of the Kochen-Specker theorem. Moreover, we show that the 01 -gadgets form a fundamental primitive that can be used to formulate state-independent and state-dependent statistical Kochen-Specker arguments as well as to give simple constructive proofs of an ``extended'' Kochen-Specker theorem first considered by Pitowsky in {\textbackslash}cite\{Pitowsky\}.}, doi = {10.22331/q-2020-08-14-308}, groups = {Pawel_H, Michal_H}, language = {en}, url = {https://quantum-journal.org/papers/q-2020-08-14-308/}, urldate = {2021-05-10}, }`

- Michał Eckstein and Paweł Horodecki. The Experiment Paradox in Physics.
*Foundations of Science*, oct 2020. doi:10.1007/s10699-020-09711-y

[BibTeX] [Abstract] [Download PDF]

Abstract Modern physics is founded on two mainstays: mathematical modelling and empirical verification. These two assumptions are prerequisite for the objectivity of scientific discourse. Here we show, however, that they are contradictory, leading to the ‘experiment paradox’. We reveal that any experiment performed on a physical system is—by necessity—invasive and thus establishes inevitable limits to the accuracy of any mathematical model. We track its manifestations in both classical and quantum physics and show how it is overcome ‘in practice’ via the concept of environment. We argue that the unravelled paradox induces a new type of ‘ontic’ underdetermination, which has deep consequences for the methodological foundations of physics.

`@Article{eckstein_experiment_2020, author = {Eckstein, Michał and Horodecki, Paweł}, journal = {Foundations of {S}cience}, title = {The {Experiment} {Paradox} in {Physics}}, year = {2020}, issn = {1233-1821, 1572-8471}, month = oct, abstract = {Abstract Modern physics is founded on two mainstays: mathematical modelling and empirical verification. These two assumptions are prerequisite for the objectivity of scientific discourse. Here we show, however, that they are contradictory, leading to the ‘experiment paradox’. We reveal that any experiment performed on a physical system is—by necessity—invasive and thus establishes inevitable limits to the accuracy of any mathematical model. We track its manifestations in both classical and quantum physics and show how it is overcome ‘in practice’ via the concept of environment. We argue that the unravelled paradox induces a new type of ‘ontic’ underdetermination, which has deep consequences for the methodological foundations of physics.}, doi = {10.1007/s10699-020-09711-y}, groups = {Pawel_H}, language = {en}, url = {http://link.springer.com/10.1007/s10699-020-09711-y}, urldate = {2021-05-10}, }`

- Alley Hameedi, Breno Marques, Piotr Mironowicz, Debashis Saha, Marcin Pawłowski, and Mohamed Bourennane. Experimental test of nonclassicality with arbitrarily low detection efficiency.
*Physical Review A*, 102(3):32621, sep 2020. doi:10.1103/PhysRevA.102.032621

[BibTeX] [Download PDF]`@Article{hameedi_experimental_2020, author = {Hameedi, Alley and Marques, Breno and Mironowicz, Piotr and Saha, Debashis and Pawłowski, Marcin and Bourennane, Mohamed}, journal = {Physical {R}eview {A}}, title = {Experimental test of nonclassicality with arbitrarily low detection efficiency}, year = {2020}, issn = {2469-9926, 2469-9934}, month = sep, number = {3}, pages = {032621}, volume = {102}, doi = {10.1103/PhysRevA.102.032621}, language = {en}, url = {https://link.aps.org/doi/10.1103/PhysRevA.102.032621}, urldate = {2021-05-10}, }`

- Thao P. Le, Piotr Mironowicz, and Paweł Horodecki. Blurred quantum Darwinism across quantum reference frames.
*Physical Review A*, 102(6):62420, dec 2020. doi:10.1103/PhysRevA.102.062420

[BibTeX] [Download PDF]`@Article{le_blurred_2020, author = {Le, Thao P. and Mironowicz, Piotr and Horodecki, Paweł}, journal = {Physical {R}eview {A}}, title = {Blurred quantum {Darwinism} across quantum reference frames}, year = {2020}, issn = {2469-9926, 2469-9934}, month = dec, number = {6}, pages = {062420}, volume = {102}, doi = {10.1103/PhysRevA.102.062420}, groups = {Pawel_H}, language = {en}, url = {https://link.aps.org/doi/10.1103/PhysRevA.102.062420}, urldate = {2021-05-10}, }`

- Michał Eckstein, Paweł Horodecki, Ryszard Horodecki, and Tomasz Miller. Operational causality in spacetime.
*Physical Review A*, 101(4):42128, apr 2020. arXiv: 1902.05002 doi:10.1103/PhysRevA.101.042128

[BibTeX] [Abstract] [Download PDF]

The no-signalling principle preventing superluminal communication is a limiting paradigm for physical theories. Within the information-theoretic framework it is commonly understood in terms of admissible correlations in composite systems. Here we unveil its complementary incarnation –- the ‘dynamical no-signalling principle’ –-, which forbids superluminal signalling via measurements on simple physical objects (e.g. particles) evolving in time. We show that it imposes strong constraints on admissible models of dynamics. The posited principle is universal –- it can be applied to any theory (classical, quantum or post-quantum) with well-defined rules of calculating detection statistics in spacetime. As an immediate application we show how one could exploit the Schr{\textbackslash}”odinger equation to establish a fully operational superluminal protocol in the Minkowski spacetime. This example illustrates how the principle can be used to identify the limits of applicability of a given model of quantum or post-quantum dynamics.

`@Article{eckstein_operational_2020, author = {Eckstein, Michał and Horodecki, Paweł and Horodecki, Ryszard and Miller, Tomasz}, journal = {Physical {R}eview {A}}, title = {Operational causality in spacetime}, year = {2020}, issn = {2469-9926, 2469-9934}, month = apr, note = {arXiv: 1902.05002}, number = {4}, pages = {042128}, volume = {101}, abstract = {The no-signalling principle preventing superluminal communication is a limiting paradigm for physical theories. Within the information-theoretic framework it is commonly understood in terms of admissible correlations in composite systems. Here we unveil its complementary incarnation --- the 'dynamical no-signalling principle' ---, which forbids superluminal signalling via measurements on simple physical objects (e.g. particles) evolving in time. We show that it imposes strong constraints on admissible models of dynamics. The posited principle is universal --- it can be applied to any theory (classical, quantum or post-quantum) with well-defined rules of calculating detection statistics in spacetime. As an immediate application we show how one could exploit the Schr{\textbackslash}"odinger equation to establish a fully operational superluminal protocol in the Minkowski spacetime. This example illustrates how the principle can be used to identify the limits of applicability of a given model of quantum or post-quantum dynamics.}, doi = {10.1103/PhysRevA.101.042128}, groups = {Pawel_H}, keywords = {Quantum Physics, General Relativity and Quantum Cosmology, Mathematical Physics, 81P16 (Primary), 81P15, 28E99, 60B05 (Secondary)}, url = {http://arxiv.org/abs/1902.05002}, urldate = {2021-05-11}, }`

- Michał Eckstein, Paweł Horodecki, Ryszard Horodecki, and Tomasz Miller. Operational causality in spacetime.
*Physical Review A*, 101(4):42128, apr 2020. arXiv: 1902.05002 doi:10.1103/PhysRevA.101.042128

[BibTeX] [Abstract] [Download PDF]

The no-signalling principle preventing superluminal communication is a limiting paradigm for physical theories. Within the information-theoretic framework it is commonly understood in terms of admissible correlations in composite systems. Here we unveil its complementary incarnation –- the ‘dynamical no-signalling principle’ –-, which forbids superluminal signalling via measurements on simple physical objects (e.g. particles) evolving in time. We show that it imposes strong constraints on admissible models of dynamics. The posited principle is universal –- it can be applied to any theory (classical, quantum or post-quantum) with well-defined rules of calculating detection statistics in spacetime. As an immediate application we show how one could exploit the Schr{\textbackslash}”odinger equation to establish a fully operational superluminal protocol in the Minkowski spacetime. This example illustrates how the principle can be used to identify the limits of applicability of a given model of quantum or post-quantum dynamics.

`@Article{eckstein_operational_2020-1, author = {Eckstein, Michał and Horodecki, Paweł and Horodecki, Ryszard and Miller, Tomasz}, journal = {Physical {R}eview {A}}, title = {Operational causality in spacetime}, year = {2020}, issn = {2469-9926, 2469-9934}, month = apr, note = {arXiv: 1902.05002}, number = {4}, pages = {042128}, volume = {101}, abstract = {The no-signalling principle preventing superluminal communication is a limiting paradigm for physical theories. Within the information-theoretic framework it is commonly understood in terms of admissible correlations in composite systems. Here we unveil its complementary incarnation --- the 'dynamical no-signalling principle' ---, which forbids superluminal signalling via measurements on simple physical objects (e.g. particles) evolving in time. We show that it imposes strong constraints on admissible models of dynamics. The posited principle is universal --- it can be applied to any theory (classical, quantum or post-quantum) with well-defined rules of calculating detection statistics in spacetime. As an immediate application we show how one could exploit the Schr{\textbackslash}"odinger equation to establish a fully operational superluminal protocol in the Minkowski spacetime. This example illustrates how the principle can be used to identify the limits of applicability of a given model of quantum or post-quantum dynamics.}, doi = {10.1103/PhysRevA.101.042128}, groups = {Pawel_H}, keywords = {Quantum Physics, General Relativity and Quantum Cosmology, Mathematical Physics, 81P16 (Primary), 81P15, 28E99, 60B05 (Secondary)}, url = {http://arxiv.org/abs/1902.05002}, urldate = {2021-07-28}, }`

### 2019

- Piotr Mironowicz and Marcin Pawłowski. Experimentally feasible semi-device-independent certification of four-outcome positive-operator-valued measurements.
*Physical Review A*, 100(3):30301, sep 2019. doi:10.1103/PhysRevA.100.030301

[BibTeX] [Download PDF]`@Article{mironowicz_experimentally_2019, author = {Mironowicz, Piotr and Pawłowski, Marcin}, journal = {Physical {R}eview {A}}, title = {Experimentally feasible semi-device-independent certification of four-outcome positive-operator-valued measurements}, year = {2019}, issn = {2469-9926, 2469-9934}, month = sep, number = {3}, pages = {030301}, volume = {100}, doi = {10.1103/PhysRevA.100.030301}, groups = {Pawlowski}, language = {en}, url = {https://link.aps.org/doi/10.1103/PhysRevA.100.030301}, urldate = {2020-04-22} }`

- Giuseppe Baio, Dariusz Chruściński, Paweł Horodecki, Antonino Messina, and Gniewomir Sarbicki. Bounds on the entanglement of two-qutrit systems from fixed marginals.
*Physical Review A*, 99(6):62312, jun 2019. doi:10.1103/PhysRevA.99.062312

[BibTeX] [Download PDF]`@Article{baio_bounds_2019, author = {Baio, Giuseppe and Chruściński, Dariusz and Horodecki, Paweł and Messina, Antonino and Sarbicki, Gniewomir}, journal = {Physical {R}eview {A}}, title = {Bounds on the entanglement of two-qutrit systems from fixed marginals}, year = {2019}, issn = {2469-9926, 2469-9934}, month = jun, number = {6}, pages = {062312}, volume = {99}, doi = {10.1103/PhysRevA.99.062312}, groups = {Pawel_H}, language = {en}, url = {https://link.aps.org/doi/10.1103/PhysRevA.99.062312}, urldate = {2020-04-22}, }`

- Paweł Horodecki and Ravishankar Ramanathan. The relativistic causality versus no-signaling paradigm for multi-party correlations.
*Nature Communications*, 10(1):1701, dec 2019. doi:10.1038/s41467-019-09505-2

[BibTeX] [Download PDF]`@Article{horodecki_relativistic_2019, author = {Horodecki, Paweł and Ramanathan, Ravishankar}, journal = {Nature {C}ommunications}, title = {The relativistic causality versus no-signaling paradigm for multi-party correlations}, year = {2019}, issn = {2041-1723}, month = dec, number = {1}, pages = {1701}, volume = {10}, doi = {10.1038/s41467-019-09505-2}, groups = {Pawel_H}, language = {en}, url = {http://www.nature.com/articles/s41467-019-09505-2}, urldate = {2020-04-22}, }`

## arXiv preprints

### 2021

- John H. Selby, Ana Belén Sainz, and Paweł Horodecki. Revisiting dynamics of quantum causal structures – when can causal order evolve?.
*Arxiv:2008.12757 [quant-ph]*, mar 2021. arXiv: 2008.12757

[BibTeX] [Abstract] [Download PDF]

Recently, there has been substantial interest in studying the dynamics of quantum theory beyond that of states, in particular, the dynamics of channels, measurements, and higher-order transformations. Ref. [Phys. Rev. X 8(1), 011047 (2018)] pursues this using the process matrix formalism, together with a definition of the possible dynamics of such process matrices, and focusing especially on the question of evolution of causal structures. One of its major conclusions is a strong theorem saying that, within the formalism, under continuous and reversible transformations, the causal order between operations must be preserved. Here we find a surprising result: if one is to take into account a full picture of the physical evolution of operations within the standard quantum-mechanical formalism, then one can actually draw the opposite conclusion. That is, we show that under certain continuous and reversible dynamics the causal order between operations is not necessarily preserved. We moreover identify and analyse the root of this apparent contradiction, specifically, that the commonly accepted and widely applied framework of higher-order processes, whilst mathematically sound, is not always appropriate for drawing conclusions on the fundamentals of physical dynamics. Finally we show how to reconcile the elements of the whole picture following the intuition based on entanglement processing by local operations and classical communication.

`@Article{selby_revisiting_2021, author = {Selby, John H. and Sainz, Ana Belén and Horodecki, Paweł}, journal = {arXiv:2008.12757 [quant-ph]}, title = {Revisiting dynamics of quantum causal structures -- when can causal order evolve?}, year = {2021}, month = mar, note = {arXiv: 2008.12757}, abstract = {Recently, there has been substantial interest in studying the dynamics of quantum theory beyond that of states, in particular, the dynamics of channels, measurements, and higher-order transformations. Ref. [Phys. Rev. X 8(1), 011047 (2018)] pursues this using the process matrix formalism, together with a definition of the possible dynamics of such process matrices, and focusing especially on the question of evolution of causal structures. One of its major conclusions is a strong theorem saying that, within the formalism, under continuous and reversible transformations, the causal order between operations must be preserved. Here we find a surprising result: if one is to take into account a full picture of the physical evolution of operations within the standard quantum-mechanical formalism, then one can actually draw the opposite conclusion. That is, we show that under certain continuous and reversible dynamics the causal order between operations is not necessarily preserved. We moreover identify and analyse the root of this apparent contradiction, specifically, that the commonly accepted and widely applied framework of higher-order processes, whilst mathematically sound, is not always appropriate for drawing conclusions on the fundamentals of physical dynamics. Finally we show how to reconcile the elements of the whole picture following the intuition based on entanglement processing by local operations and classical communication.}, groups = {Pawel_H}, keywords = {Quantum Physics}, url = {http://arxiv.org/abs/2008.12757}, urldate = {2021-07-28}, }`

- B. Ahmadi, S. Salimi, and A. S. Khorashad. Refined Definitions of Heat and Work in Quantum Thermodynamics.
*Arxiv:1912.01983 [quant-ph]*, jul 2021. arXiv: 1912.01983

[BibTeX] [Abstract] [Download PDF]

In this paper, unambiguous redefinitions of heat and work are presented for quantum thermodynamic systems. We will use genuine reasoning based on which Clausius originally defined work and heat in establishing thermodynamics. The change in the energy which is accompanied by a change in the entropy is identified as heat, while any change in the energy which does not lead to a change in the entropy is known as work. It will be seen that quantum coherence does not allow all the energy exchanged between two quantum systems to be only of the heat form. Several examples will also be discussed. Finally, it will be shown that these refined definitions will strongly affect the entropy production of quantum thermodynamic processes giving new insight into the irreversibility of quantum processes.

`@Article{ahmadi_refined_2021, author = {Ahmadi, B. and Salimi, S. and Khorashad, A. S.}, journal = {arXiv:1912.01983 [quant-ph]}, title = {Refined {Definitions} of {Heat} and {Work} in {Quantum} {Thermodynamics}}, year = {2021}, month = jul, note = {arXiv: 1912.01983}, abstract = {In this paper, unambiguous redefinitions of heat and work are presented for quantum thermodynamic systems. We will use genuine reasoning based on which Clausius originally defined work and heat in establishing thermodynamics. The change in the energy which is accompanied by a change in the entropy is identified as heat, while any change in the energy which does not lead to a change in the entropy is known as work. It will be seen that quantum coherence does not allow all the energy exchanged between two quantum systems to be only of the heat form. Several examples will also be discussed. Finally, it will be shown that these refined definitions will strongly affect the entropy production of quantum thermodynamic processes giving new insight into the irreversibility of quantum processes.}, keywords = {Quantum Physics}, url = {http://arxiv.org/abs/1912.01983}, urldate = {2021-07-28}, }`

### 2020

- Ravishankar Ramanathan, Michał Horodecki, Hammad Anwer, Stefano Pironio, Karol Horodecki, Marcus Grünfeld, Sadiq Muhammad, Mohamed Bourennane, and Paweł Horodecki. Practical No-Signalling proof Randomness Amplification using Hardy paradoxes and its experimental implementation.
*Arxiv:1810.11648 [quant-ph]*, 2020. arXiv: 1810.11648

[BibTeX] [Abstract] [Download PDF]

Device-Independent (DI) security is the best form of quantum cryptography, providing information-theoretic security based on the very laws of nature. In its highest form, security is guaranteed against adversaries limited only by the no-superluminal signalling rule of relativity. The task of randomness amplification, to generate secure fully uniform bits starting from weakly random seeds, is of both cryptographic and foundational interest, being important for the generation of cryptographically secure random numbers as well as bringing deep connections to the existence of free-will. DI no-signalling proof protocols for this fundamental task have thus far relied on esoteric proofs of non-locality termed pseudo-telepathy games, complicated multi-party setups or high-dimensional quantum systems, and have remained out of reach of experimental implementation. In this paper, we construct the first practically relevant no-signalling proof DI protocols for randomness amplification based on the simplest proofs of Bell non-locality and illustrate them with an experimental implementation in a quantum optical setup using polarised photons. Technically, we relate the problem to the vast field of Hardy paradoxes, without which it would be impossible to achieve amplification of arbitrarily weak sources in the simplest Bell non-locality scenario consisting of two parties choosing between two binary inputs. Furthermore, we identify a deep connection between proofs of the celebrated Kochen-Specker theorem and Hardy paradoxes that enables us to construct Hardy paradoxes with the non-zero probability taking any value in \$(0,1]\$. Our methods enable us, under the fair-sampling assumption of the experiment, to realize up to \$25\$ bits of randomness in \$20\$ hours of experimental data collection from an initial private source of randomness \$0.1\$ away from uniform.

`@Article{ramanathan_practical_2020, author = {Ramanathan, Ravishankar and Horodecki, Michał and Anwer, Hammad and Pironio, Stefano and Horodecki, Karol and Grünfeld, Marcus and Muhammad, Sadiq and Bourennane, Mohamed and Horodecki, Paweł}, journal = {arXiv:1810.11648 [quant-ph]}, title = {Practical {No}-{Signalling} proof {Randomness} {Amplification} using {Hardy} paradoxes and its experimental implementation}, year = {2020}, month = sep, note = {arXiv: 1810.11648}, abstract = {Device-Independent (DI) security is the best form of quantum cryptography, providing information-theoretic security based on the very laws of nature. In its highest form, security is guaranteed against adversaries limited only by the no-superluminal signalling rule of relativity. The task of randomness amplification, to generate secure fully uniform bits starting from weakly random seeds, is of both cryptographic and foundational interest, being important for the generation of cryptographically secure random numbers as well as bringing deep connections to the existence of free-will. DI no-signalling proof protocols for this fundamental task have thus far relied on esoteric proofs of non-locality termed pseudo-telepathy games, complicated multi-party setups or high-dimensional quantum systems, and have remained out of reach of experimental implementation. In this paper, we construct the first practically relevant no-signalling proof DI protocols for randomness amplification based on the simplest proofs of Bell non-locality and illustrate them with an experimental implementation in a quantum optical setup using polarised photons. Technically, we relate the problem to the vast field of Hardy paradoxes, without which it would be impossible to achieve amplification of arbitrarily weak sources in the simplest Bell non-locality scenario consisting of two parties choosing between two binary inputs. Furthermore, we identify a deep connection between proofs of the celebrated Kochen-Specker theorem and Hardy paradoxes that enables us to construct Hardy paradoxes with the non-zero probability taking any value in \$(0,1]\$. Our methods enable us, under the fair-sampling assumption of the experiment, to realize up to \$25\$ bits of randomness in \$20\$ hours of experimental data collection from an initial private source of randomness \$0.1\$ away from uniform.}, groups = {Michal_H, Pawel_H}, keywords = {Quantum Physics}, url = {http://arxiv.org/abs/1810.11648}, urldate = {2021-05-11}, }`

- Michał Banacki, Marcin Marciniak, Karol Horodecki, and Paweł Horodecki. Information backflow may not indicate quantum memory.
*Arxiv:2008.12638 [quant-ph]*, 2020. arXiv: 2008.12638

[BibTeX] [Abstract] [Download PDF]

We analyze recent approaches to quantum Markovianity and how they relate to the proper definition of quantum memory. We point out that the well-known criterion of information backflow may not correctly report character of the memory falsely signaling its quantumness. Therefore, as a complement to the well-known criteria, we propose several concepts of elementary dynamical maps. Maps of this type do not increase distinguishability of states which are indistinguishable by von Neumann measurements in a given basis. Those notions and convexity allows us to define general classes of processes without quantum memory in a weak and strong sense. Finally, we provide a practical characterization of the most intuitive class in terms of the new concept of witness of quantum information backflow.

`@Article{banacki_information_2020, author = {Banacki, Michał and Marciniak, Marcin and Horodecki, Karol and Horodecki, Paweł}, journal = {arXiv:2008.12638 [quant-ph]}, title = {Information backflow may not indicate quantum memory}, year = {2020}, month = aug, note = {arXiv: 2008.12638}, abstract = {We analyze recent approaches to quantum Markovianity and how they relate to the proper definition of quantum memory. We point out that the well-known criterion of information backflow may not correctly report character of the memory falsely signaling its quantumness. Therefore, as a complement to the well-known criteria, we propose several concepts of elementary dynamical maps. Maps of this type do not increase distinguishability of states which are indistinguishable by von Neumann measurements in a given basis. Those notions and convexity allows us to define general classes of processes without quantum memory in a weak and strong sense. Finally, we provide a practical characterization of the most intuitive class in terms of the new concept of witness of quantum information backflow.}, groups = {Pawel_H}, keywords = {Quantum Physics}, url = {http://arxiv.org/abs/2008.12638}, urldate = {2021-07-28}, }`

- Ravishankar Ramanathan, Michał Banacki, Ricard Ravell Rodríguez, and Paweł Horodecki. Single trusted qubit is necessary and sufficient for quantum realisation of extremal no-signaling correlations.
*Arxiv:2004.14782 [quant-ph]*, apr 2020. arXiv: 2004.14782

[BibTeX] [Abstract] [Download PDF]

Quantum statistics can be considered from the perspective of postquantum no-signaling theories in which either none or only a certain number of quantum systems are trusted. In these scenarios, the role of states is played by the so-called no-signaling boxes or no-signaling assemblages respectively. It has been shown so far that in the usual Bell non-locality scenario with a single measurement run, quantum statistics can never reproduce an extremal non-local point within the set of no-signaling boxes. We provide here a general no-go rule showing that the latter stays true even if arbitrary sequential measurements are allowed. On the other hand, we prove a positive result showing that already a single trusted qubit is enough for quantum theory to produce a self-testable extremal point within the corresponding set of no-signaling assemblages. This result opens up the possibility for security proofs of cryptographic protocols against general no-signaling adversaries.

`@Article{ramanathan_single_2020, author = {Ramanathan, Ravishankar and Banacki, Michał and Rodríguez, Ricard Ravell and Horodecki, Paweł}, journal = {arXiv:2004.14782 [quant-ph]}, title = {Single trusted qubit is necessary and sufficient for quantum realisation of extremal no-signaling correlations}, year = {2020}, month = apr, note = {arXiv: 2004.14782}, abstract = {Quantum statistics can be considered from the perspective of postquantum no-signaling theories in which either none or only a certain number of quantum systems are trusted. In these scenarios, the role of states is played by the so-called no-signaling boxes or no-signaling assemblages respectively. It has been shown so far that in the usual Bell non-locality scenario with a single measurement run, quantum statistics can never reproduce an extremal non-local point within the set of no-signaling boxes. We provide here a general no-go rule showing that the latter stays true even if arbitrary sequential measurements are allowed. On the other hand, we prove a positive result showing that already a single trusted qubit is enough for quantum theory to produce a self-testable extremal point within the corresponding set of no-signaling assemblages. This result opens up the possibility for security proofs of cryptographic protocols against general no-signaling adversaries.}, groups = {Pawel_H}, keywords = {Quantum Physics}, url = {http://arxiv.org/abs/2004.14782}, urldate = {2021-07-28}, }`

- B. Ahmadi, S. Salimi, and A. S. Khorashad. No Entropy Production in Quantum Thermodynamics.
*Arxiv:2002.10747 [quant-ph]*, feb 2020. arXiv: 2002.10747

[BibTeX] [Abstract] [Download PDF]

In this work we will show that there exists a fundamental difference between microscopic quantum thermodynamics and macroscopic classical thermodynamics. It will be proved that the entropy production in quantum thermodynamics always vanishes for both closed and open quantum thermodynamic systems. This novel and very surprising result is derived based on the genuine reasoning Clausius used to establish the science of thermodynamics in the first place. This result will interestingly lead to define the generalized temperature for any non-equilibrium quantum system.

`@article{ahmadi_no_2020, title = {No {Entropy} {Production} in {Quantum} {Thermodynamics}}, url = {http://arxiv.org/abs/2002.10747}, abstract = {In this work we will show that there exists a fundamental difference between microscopic quantum thermodynamics and macroscopic classical thermodynamics. It will be proved that the entropy production in quantum thermodynamics always vanishes for both closed and open quantum thermodynamic systems. This novel and very surprising result is derived based on the genuine reasoning Clausius used to establish the science of thermodynamics in the first place. This result will interestingly lead to define the generalized temperature for any non-equilibrium quantum system.}, urldate = {2021-07-28}, journal = {arXiv:2002.10747 [quant-ph]}, author = {Ahmadi, B. and Salimi, S. and Khorashad, A. S.}, month = feb, year = {2020}, note = {arXiv: 2002.10747}, keywords = {Quantum Physics}, }`

### 2019

- Michał Eckstein and Paweł Horodecki. The experiment paradox in physics.
*Arxiv:1904.04117 [gr-qc, physics:hep-th, physics:physics, physics:quant-ph]*, apr 2019. arXiv: 1904.04117

[BibTeX] [Abstract] [Download PDF]

Modern physics is founded on two mainstays: mathematical modelling and empirical verification. These two assumptions are prerequisite for the objectivity of scientific discourse. Here we show, however, that they are contradictory, leading to the `experiment paradox’. We reveal that any experiment performed on a physical system is – by necessity – invasive and thus establishes inevitable limits to the accuracy of any mathematical model. We track its manifestations in both classical and quantum physics and show how it is overcome `in practice’ via the concept of environment. We argue that the scientific pragmatism ordains two methodological principles of compressibility and stability.

`@Article{eckstein_experiment_2019, author = {Eckstein, Michał and Horodecki, Paweł}, journal = {arXiv:1904.04117 [gr-qc, physics:hep-th, physics:physics, physics:quant-ph]}, title = {The experiment paradox in physics}, year = {2019}, month = apr, note = {arXiv: 1904.04117}, abstract = {Modern physics is founded on two mainstays: mathematical modelling and empirical verification. These two assumptions are prerequisite for the objectivity of scientific discourse. Here we show, however, that they are contradictory, leading to the `experiment paradox'. We reveal that any experiment performed on a physical system is - by necessity - invasive and thus establishes inevitable limits to the accuracy of any mathematical model. We track its manifestations in both classical and quantum physics and show how it is overcome `in practice' via the concept of environment. We argue that the scientific pragmatism ordains two methodological principles of compressibility and stability.}, groups = {Pawel_H}, keywords = {Physics - History and Philosophy of Physics, General Relativity and Quantum Cosmology, High Energy Physics - Theory, Physics - Classical Physics, Quantum Physics}, url = {http://arxiv.org/abs/1904.04117}, urldate = {2021-07-28}, }`

- Sumit Rout, Ananda G. Maity, Amit Mukherjee, Saronath Halder, and Manik Banik. Multiparty orthogonal product states with minimal genuine nonlocality.
*Arxiv:1910.14308 [quant-ph]*, oct 2019.

[BibTeX] [Abstract] [Download PDF]

Nonlocality without entanglement and its subsequent generalizations offer deep information-theoretic insights and subsequently find several useful applications. Concept of genuinely nonlocal set of product states emerges as a natural multipartite generalization of this phenomenon. Existence of such sets eventually motivates the problem concerning their entanglement-assisted discrimination. Here, we construct examples of genuinely nonlocal product states for arbitrary number of parties. Strength of genuine nonlocality of these sets can be considered minimal as their perfect discrimination is possible with entangled resources residing in Hilbert spaces having the smallest possible dimensions. Our constructions lead to fully separable measurements that are impossible to implement even if all but one party come together. Furthermore, they also provide the opportunity to compare different multipartite states that otherwise are incomparable under single copy local manipulation.

`@Article{Rout2019, author = {Sumit Rout and Ananda G. Maity and Amit Mukherjee and Saronath Halder and Manik Banik}, journal = {arXiv:1910.14308 [quant-ph]}, title = {Multiparty orthogonal product states with minimal genuine nonlocality}, year = {2019}, month = oct, abstract = {Nonlocality without entanglement and its subsequent generalizations offer deep information-theoretic insights and subsequently find several useful applications. Concept of genuinely nonlocal set of product states emerges as a natural multipartite generalization of this phenomenon. Existence of such sets eventually motivates the problem concerning their entanglement-assisted discrimination. Here, we construct examples of genuinely nonlocal product states for arbitrary number of parties. Strength of genuine nonlocality of these sets can be considered minimal as their perfect discrimination is possible with entangled resources residing in Hilbert spaces having the smallest possible dimensions. Our constructions lead to fully separable measurements that are impossible to implement even if all but one party come together. Furthermore, they also provide the opportunity to compare different multipartite states that otherwise are incomparable under single copy local manipulation.}, archiveprefix = {arXiv}, eprint = {1910.14308}, keywords = {quant-ph}, primaryclass = {quant-ph}, url = {https://arxiv.org/pdf/1910.14308}, }`

## Group members

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## Former members

__Keywords:__ quantum entanglement, quantum contextuality, quantum computational speedup, quantum capacity, quantum channels, quantum reduction of communication complexity, violations of local realism, Bell’s theorem, resource theory of thermodynamics, resource theories, quantum networks, private bits, quantum privacy, quantum randomness, randomness amplification, device-independent randomness amplification, randomness extraction.