##### Leader of the research group: Marcin Pawłowski

Post-docs: Akshata Shenoy, Karthik Hosapete Seshadri, Pedro Ruas-Dieguez, Giovanni Scala

PhD student: Anubhav Chaturvedi, Giuseppe Viola, Chithra Raj, Tushita Prasad, Ekta Panwar

MSc student: Jakub Gnyp, Marcin Klaczak

The broad aim of the Quantum Cybersecurity and Communication Group is to develop quantum solutions for problems in communication and information security.

## Activity

Specific goals include the development of:

– Quantum key distribution protocols with low hardware requirements.

– Quantum true random number generators.

– Existing and new quantum cryptographic primitives.

– Methods for secure communication and computation.

– Formal security proofs of quantum cryptographic protocols.

– Tools for cryptoanalysis.

– Commercialisation and industrial outreach.

## Publications

### 2023

- Ismael L. Paiva, Pedro R. Dieguez, Renato M. Angelo, and Eliahu Cohen. Coherence and realism in the Aharonov-Bohm effect.
*Physical Review A*, 107(3):032213, mar 2023. doi:10.1103/PhysRevA.107.032213

[BibTeX] [Abstract] [Download PDF]

The Aharonov-Bohm effect is a fundamental topological phenomenon with a wide range of applications. It consists of a charge encircling a region with a magnetic flux in a superposition of wave packets having their relative phase affected by the flux. In this work we analyze this effect using an entropic measure known as realism, originally introduced as a quantifier of a system’s degree of reality and mathematically related to notions of global and local quantum coherence. More precisely, we look for observables that lead to gauge-invariant realism associated with the charge before it completes its loop. We find that the realism of these operators has a sudden change when the line connecting the center of both wave packets crosses the solenoid. Moreover, we consider the case of a quantized magnetic-field source, pointing out similarities and differences between the two cases. Finally, we discuss some consequences of these results.

`@Article{Paiva2023, author = {Paiva, Ismael L. and Dieguez, Pedro R. and Angelo, Renato M. and Cohen, Eliahu}, journal = {Physical Review A}, title = {Coherence and realism in the Aharonov-Bohm effect}, year = {2023}, month = mar, number = {3}, pages = {032213}, volume = {107}, abstract = {The Aharonov-Bohm effect is a fundamental topological phenomenon with a wide range of applications. It consists of a charge encircling a region with a magnetic flux in a superposition of wave packets having their relative phase affected by the flux. In this work we analyze this effect using an entropic measure known as realism, originally introduced as a quantifier of a system's degree of reality and mathematically related to notions of global and local quantum coherence. More precisely, we look for observables that lead to gauge-invariant realism associated with the charge before it completes its loop. We find that the realism of these operators has a sudden change when the line connecting the center of both wave packets crosses the solenoid. Moreover, we consider the case of a quantized magnetic-field source, pointing out similarities and differences between the two cases. Finally, we discuss some consequences of these results.}, archiveprefix = {arXiv}, doi = {10.1103/PhysRevA.107.032213}, eid = {032213}, eprint = {2209.00480}, keywords = {Quantum Physics}, primaryclass = {quant-ph}, url = {https://ui.adsabs.harvard.edu/abs/2023PhRvA.107c2213P}, }`

- Pedro R. Dieguez, Vinicius F. Lisboa, and Roberto M. Serra. Thermal devices powered by generalized measurements with indefinite causal order.
*Physical Review A*, 107(1):012423, jan 2023. doi:10.1103/PhysRevA.107.012423

[BibTeX] [Abstract] [Download PDF]

A quantum-controlled device may produce a scenario in which two general quantum operations can be performed in such a way that it is not possible to associate a definite order for the operation’s application. Such an indefinite causal order can be explored to produce nontrivial effects in quantum thermal devices. We investigate a measurement-powered thermal device that consists of generalized measurement channels with adjustable intensity parameters, where energy is exchanged with the apparatus in the form of work or heat. The measurement-based device can operate as a heat engine, a thermal accelerator, or a refrigerator, according to a measurement intensity setting. By employing a quantum switch of two measurement channels, we explore a thermal device fueled by an indefinite causal order. We also discuss how a coherent control over an indefinite causal order structure can change the operating regimes of the measurement-powered thermal device to produce an advantage when compared to a scenario with an incoherent control of the order switch.

`@Article{Dieguez2023, author = {Dieguez, Pedro R. and Lisboa, Vinicius F. and Serra, Roberto M.}, journal = {Physical Review A}, title = {Thermal devices powered by generalized measurements with indefinite causal order}, year = {2023}, month = jan, number = {1}, pages = {012423}, volume = {107}, abstract = {A quantum-controlled device may produce a scenario in which two general quantum operations can be performed in such a way that it is not possible to associate a definite order for the operation's application. Such an indefinite causal order can be explored to produce nontrivial effects in quantum thermal devices. We investigate a measurement-powered thermal device that consists of generalized measurement channels with adjustable intensity parameters, where energy is exchanged with the apparatus in the form of work or heat. The measurement-based device can operate as a heat engine, a thermal accelerator, or a refrigerator, according to a measurement intensity setting. By employing a quantum switch of two measurement channels, we explore a thermal device fueled by an indefinite causal order. We also discuss how a coherent control over an indefinite causal order structure can change the operating regimes of the measurement-powered thermal device to produce an advantage when compared to a scenario with an incoherent control of the order switch.}, archiveprefix = {arXiv}, doi = {10.1103/PhysRevA.107.012423}, eid = {012423}, eprint = {2205.14406}, keywords = {Quantum Physics}, primaryclass = {quant-ph}, url = {https://ui.adsabs.harvard.edu/abs/2023PhRvA.107a2423D}, }`

- C. ~H. ~S. Vieira, J. ~L. ~D. de Oliveira, J. ~F. ~G. Santos, P. ~R. Dieguez, and R. ~M. Serra. Exploring quantum thermodynamics with NMR.
*Journal of Magnetic Resonance Open*, 16:105, mar 2023. doi:10.1016/j.jmro.2023.100105

[BibTeX] [Abstract] [Download PDF]

Quantum thermodynamics seeks to extend non-equilibrium stochastic thermodynamics to small quantum systems where non-classical features are essential to its description. Such a research area has recently provided meaningful theoretical and experimental advances by exploring the wealth and the power of quantum features along with informational aspects of a system’s thermodynamics. The relevance of such investigations is related to the fact that quantum technological devices are currently at the forefront of science and engineering applications. This short review article provides an overview of some concepts in quantum thermodynamics highlighting test-of-principles experiments using nuclear magnetic resonance techniques.

`@Article{Vieira2023, author = {Vieira, C.~H.~S. and de Oliveira, J.~L.~D. and Santos, J.~F.~G. and Dieguez, P.~R. and Serra, R.~M.}, journal = {Journal of Magnetic Resonance Open}, title = {Exploring quantum thermodynamics with NMR}, year = {2023}, month = mar, pages = {105}, volume = {16}, abstract = {Quantum thermodynamics seeks to extend non-equilibrium stochastic thermodynamics to small quantum systems where non-classical features are essential to its description. Such a research area has recently provided meaningful theoretical and experimental advances by exploring the wealth and the power of quantum features along with informational aspects of a system's thermodynamics. The relevance of such investigations is related to the fact that quantum technological devices are currently at the forefront of science and engineering applications. This short review article provides an overview of some concepts in quantum thermodynamics highlighting test-of-principles experiments using nuclear magnetic resonance techniques.}, archiveprefix = {arXiv}, doi = {10.1016/j.jmro.2023.100105}, eprint = {2303.08917}, keywords = {Quantum Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Statistical Mechanics}, primaryclass = {quant-ph}, url = {https://ui.adsabs.harvard.edu/abs/2023JMRO...1600105V}, }`

### 2022

- Mariami Gachechiladze, Bartłomiej Bkak, Marcin Pawłowski, and Nikolai Miklin. Quantum Bell inequalities from Information Causality \textendash tight for Macroscopic Locality.
*Quantum*, 6:717, may 2022. acknowledgment to ICTQT IRAP project included doi:10.22331/q-2022-05-24-717

[BibTeX] [Download PDF]`@article{Gachechiladze_2022, doi = {10.22331/q-2022-05-24-717}, url = {https://doi.org/10.22331/q-2022-05-24-717}, year = 2022, month = may, publisher = {Verein zur Forderung des Open Access Publizierens in den Quantenwissenschaften}, volume = {6}, pages = {717}, author = {Mariami Gachechiladze and Bart{\l}omiej B{\k{a}}k and Marcin Paw{\l}owski and Nikolai Miklin}, title = {Quantum Bell inequalities from Information Causality {\textendash} tight for Macroscopic Locality}, journal = {Quantum}, note = {acknowledgment to ICTQT IRAP project included} }`

- Marcin Karczewski, Giovanni Scala, Antonio Mandarino, Ana Belén Sainz, and Marek Żukowski. Avenues to generalising Bell inequalities.
*Journal of Physics A: Mathematical and Theoretical*, 55:384011, 2022. doi:10.1088/1751-8121/ac8a28

[BibTeX]`@article{karczewski2022avenues, title={Avenues to generalising Bell inequalities}, author={Karczewski, Marcin and Scala, Giovanni and Mandarino, Antonio and Sainz, Ana Bel{\'e}n and {\.Z}ukowski, Marek}, journal={Journal of Physics A: Mathematical and Theoretical}, year={2022}, volume={55}, pages={384011}, publisher={IOP Publishing}, doi={10.1088/1751-8121/ac8a28} }`

- Michał Banacki, Piotr Mironowicz, Ravishankar Ramanathan, and Paweł Horodecki. Hybrid no-signaling-quantum correlations.
*New Journal of Physics*, 24(8):083003, aug 2022. acknowledgement for ICTQT IRAP included doi:10.1088/1367-2630/ac7fb3

[BibTeX] [Abstract] [Download PDF]

Fundamental investigations in non-locality have shown that while the no-signaling principle alone is not sufficient to single out the set of quantum non-local correlations, local quantum mechanics and no-signaling together exactly reproduce the set of quantum correlations in the two-party Bell scenario. Here, we introduce and study an intermediate hybrid no-signaling quantum set of non-local correlations that we term \textbfHNSQ in the multi-party Bell scenario where some subsystems are locally quantum while the remaining subsystems are only constrained by the no-signaling principle. Specifically, the set \textbfHNSQ is a super-quantum set of correlations derived from no-signaling assemblages by performing quantum measurements on the trusted subsystems. We show that in contrast to the set \textbfNS of no-signaling behaviors, there exist extreme points of \textbfHNSQ in the tripartite Bell scenario that admit quantum realization. As a tool for optimization over the set \textbfHNSQ, we introduce an outer hierarchy of semi-definite programming approximations to the set following an approach put forward by Doherty–Parrilo–Spedalieri. We perform an extensive numerical analysis of the maximal violation of the facet Bell inequalities in the three-party binary input–output scenario and study the corresponding self-testing properties. In contrast to the usual no-signaling correlations, the new set allows for simple security proofs of (one-sided)-device-independent applications against super-quantum adversaries.

`@Article{banacki_hybrid_2022, author= {Banacki, Michał and Mironowicz, Piotr and Ramanathan, Ravishankar and Horodecki, Paweł}, journal = {New Journal of Physics}, title = {Hybrid no-signaling-quantum correlations}, note= {acknowledgement for ICTQT IRAP included}, year= {2022}, month = aug, number= {8}, pages = {083003}, volume= {24}, abstract= {Fundamental investigations in non-locality have shown that while the no-signaling principle alone is not sufficient to single out the set of quantum non-local correlations, local quantum mechanics and no-signaling together exactly reproduce the set of quantum correlations in the two-party Bell scenario. Here, we introduce and study an intermediate hybrid no-signaling quantum set of non-local correlations that we term \textbf{HNSQ} in the multi-party Bell scenario where some subsystems are locally quantum while the remaining subsystems are only constrained by the no-signaling principle. Specifically, the set \textbf{HNSQ} is a super-quantum set of correlations derived from no-signaling assemblages by performing quantum measurements on the trusted subsystems. We show that in contrast to the set \textbf{NS} of no-signaling behaviors, there exist extreme points of \textbf{HNSQ} in the tripartite Bell scenario that admit quantum realization. As a tool for optimization over the set \textbf{HNSQ}, we introduce an outer hierarchy of semi-definite programming approximations to the set following an approach put forward by Doherty–Parrilo–Spedalieri. We perform an extensive numerical analysis of the maximal violation of the facet Bell inequalities in the three-party binary input–output scenario and study the corresponding self-testing properties. In contrast to the usual no-signaling correlations, the new set allows for simple security proofs of (one-sided)-device-independent applications against super-quantum adversaries.}, groups = {Pawel_H}, doi = {10.1088/1367-2630/ac7fb3}, keywords = {Quantum Physics}, url = {https://iopscience.iop.org/article/10.1088/1367-2630/ac7fb3}, }`

- Pedro R. Dieguez, Jéferson R. Guimar~aes, John PS Peterson, Renato M. Angelo, and Roberto M. Serra. Experimental assessment of physical realism in a quantum-controlled device.
*Communications Physics*, 5(1):1-8, 2022. doi:10.1038/s42005-022-00828-z

[BibTeX] [Download PDF]`@article{dieguez2022experimental, title={Experimental assessment of physical realism in a quantum-controlled device}, author={Dieguez, Pedro R and Guimar{\~a}es, J{\'e}ferson R and Peterson, John PS and Angelo, Renato M and Serra, Roberto M}, journal={Communications Physics}, volume={5}, number={1}, pages={1--8}, year={2022}, doi={10.1038/s42005-022-00828-z}, url={https://doi.org/10.1038/s42005-022-00828-z}, publisher={Nature Publishing Group} }`

- VS Gomes, PR Dieguez, and HM Vasconcelos. Realism-based nonlocality: Invariance under local unitary operations and asymptotic decay for thermal correlated states.
*Physica A: Statistical Mechanics and its Applications*, page 127568, 2022. doi:10.1016/j.physa.2022.127568

[BibTeX] [Download PDF]`@article{gomes2022realism, title={Realism-based nonlocality: Invariance under local unitary operations and asymptotic decay for thermal correlated states}, author={Gomes, VS and Dieguez, PR and Vasconcelos, HM}, journal={Physica A: Statistical Mechanics and its Applications}, pages={127568}, year={2022}, doi={10.1016/j.physa.2022.127568}, url={https://doi.org/10.1016/j.physa.2022.127568}, publisher={Elsevier} }`

- V. F. Lisboa, P. R. Dieguez, J. R. Guimar~aes, J. F. G. Santos, and R. M. Serra. Experimental investigation of a quantum heat engine powered by generalized measurements.
*Phys. Rev. A*, 106:022436, aug 2022. doi:10.1103/PhysRevA.106.022436

[BibTeX] [Download PDF]`@article{PhysRevA.106.022436, title = {Experimental investigation of a quantum heat engine powered by generalized measurements}, author = {Lisboa, V. F. and Dieguez, P. R. and Guimar\~aes, J. R. and Santos, J. F. G. and Serra, R. M.}, journal = {Phys. Rev. A}, volume = {106}, issue = {2}, pages = {022436}, numpages = {8}, year = {2022}, month = aug, publisher = {American Physical Society}, doi = {10.1103/PhysRevA.106.022436}, url = {https://link.aps.org/doi/10.1103/PhysRevA.106.022436} }`

- Piotr Mironowicz, Paweł Horodecki, and Ryszard Horodecki. Non-Perfect Propagation of Information to a Noisy Environment with Self-Evolution.
*Entropy*, 24(4), mar 2022. acknowledgement for ICTQT IRAP included doi:10.3390/e24040467

[BibTeX] [Abstract] [Download PDF]

We study the non-perfect propagation of information for evolving a low-dimensional environment that includes self-evolution as well as noisy initial states and analyse the interrelations between the degree of objectivization and environment parameters. In particular, we consider an analytical model of three interacting qubits and derive its objectivity parameters. The numerical analysis shows that the quality of the spectrum broadcast structure formed during the interaction may exhibit non-monotonicity both in the speed of self-dynamics of the environment as well as its mixedness. The former effect is particularly strong, showing that—considering part of the environment as a measurement apparatus—an increase of the external magnetic field acting on the environment may turn the vague measurement into close to ideal. The above effects suggest that quantum objectivity may appear after increasing the dynamics of the environment, although not with respect to the pointer basis, but some other, which we call the generalized pointer or indicator basis. Furthermore, it seems also that, when the objectivity is poor, it may be improved, at least by some amount, by increasing the thermal noise. We provide further evidence of this by analysing the upper bounds on distance to the set of states representing perfect objectivity in the case of a higher number of qubits.

`@article{Mironowicz_non-perfect_2022, author = {Mironowicz, Piotr and Horodecki, Paweł and Horodecki, Ryszard}, title = {Non-Perfect Propagation of Information to a Noisy Environment with Self-Evolution}, note= {acknowledgement for ICTQT IRAP included}, journal = {Entropy}, volume = {24}, year = {2022}, month = mar, number = {4}, article-number = {467}, url = {https://www.mdpi.com/1099-4300/24/4/467}, PubMedID = {35455130}, ISSN = {1099-4300}, abstract = {We study the non-perfect propagation of information for evolving a low-dimensional environment that includes self-evolution as well as noisy initial states and analyse the interrelations between the degree of objectivization and environment parameters. In particular, we consider an analytical model of three interacting qubits and derive its objectivity parameters. The numerical analysis shows that the quality of the spectrum broadcast structure formed during the interaction may exhibit non-monotonicity both in the speed of self-dynamics of the environment as well as its mixedness. The former effect is particularly strong, showing that—considering part of the environment as a measurement apparatus—an increase of the external magnetic field acting on the environment may turn the vague measurement into close to ideal. The above effects suggest that quantum objectivity may appear after increasing the dynamics of the environment, although not with respect to the pointer basis, but some other, which we call the generalized pointer or indicator basis. Furthermore, it seems also that, when the objectivity is poor, it may be improved, at least by some amount, by increasing the thermal noise. We provide further evidence of this by analysing the upper bounds on distance to the set of states representing perfect objectivity in the case of a higher number of qubits.}, groups = {Pawel_H}, doi = {10.3390/e24040467}, }`

- Francesco V. Pepe, Giovanni Scala, Gabriele Chilleri, Danilo Triggiani, Yoon-Ho Kim, and Vincenzo Tamma. Distance sensitivity of thermal light second-order interference beyond spatial coherence.
*The European Physical Journal Plus*, 137(6):647, jun 2022. doi:10.1140/epjp/s13360-022-02857-7

[BibTeX] [Abstract] [Download PDF]

We demonstrate the distance sensitivity of thermal light second-order interference beyond spatial coherence. This kind of interference, emerging from the measurement of the correlation between intensity fluctuations on two detectors, is sensitive to the distances separating a remote mask from the source and the detector, even when such information cannot be retrieved by first-order intensity measurements. We show how the sensitivity to such distances is intimately connected to the degree of correlation of the measured interference pattern in different experimental scenarios and independently of the spectral properties of light. Remarkably, in specific configurations, sensitivity to the distances of remote objects can be preserved even in the presence of turbulence. Unlike in previous schemes, such a distance sensitivity is reflected in the fundamental emergence of new critical parameters which benchmark the degree of second-order correlation, describing the counterintuitive emergence of spatial second-order interference not only in the absence of (first-order) coherence at both detectors but also when first-order interference is observed at one of the two detectors.

`@Article{Pepe2022, author = {Pepe, Francesco V. and Scala, Giovanni and Chilleri, Gabriele and Triggiani, Danilo and Kim, Yoon-Ho and Tamma, Vincenzo}, journal = {The European Physical Journal Plus}, title = {Distance sensitivity of thermal light second-order interference beyond spatial coherence}, year = {2022}, month = jun, number = {6}, pages = {647}, volume = {137}, abstract = {We demonstrate the distance sensitivity of thermal light second-order interference beyond spatial coherence. This kind of interference, emerging from the measurement of the correlation between intensity fluctuations on two detectors, is sensitive to the distances separating a remote mask from the source and the detector, even when such information cannot be retrieved by first-order intensity measurements. We show how the sensitivity to such distances is intimately connected to the degree of correlation of the measured interference pattern in different experimental scenarios and independently of the spectral properties of light. Remarkably, in specific configurations, sensitivity to the distances of remote objects can be preserved even in the presence of turbulence. Unlike in previous schemes, such a distance sensitivity is reflected in the fundamental emergence of new critical parameters which benchmark the degree of second-order correlation, describing the counterintuitive emergence of spatial second-order interference not only in the absence of (first-order) coherence at both detectors but also when first-order interference is observed at one of the two detectors.}, doi = {10.1140/epjp/s13360-022-02857-7}, eid = {647}, url = {https://ui.adsabs.harvard.edu/abs/2022EPJP..137..647P}, }`

### 2021

- 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}, }`

- Nikolai Miklin and Marcin Pawłowski. Information Causality without concatenation.
*Physical Review Letters*, 126(22):220403, jun 2021. arXiv: 2101.12710 doi:10.1103/PhysRevLett.126.220403

[BibTeX] [Abstract] [Download PDF]

Information Causality is a physical principle which states that the amount of randomly accessible data over a classical communication channel cannot exceed its capacity, even if the sender and the receiver have access to a source of nonlocal correlations. This principle can be used to bound the nonlocality of quantum mechanics without resorting to its full formalism, with a notable example of reproducing the Tsirelson’s bound of the Clauser-Horne-Shimony-Holt inequality. Despite being promising, the latter result found little generalization to other Bell inequalities because of the limitations imposed by the process of concatenation, in which several nonsignaling resources are put together to produce tighter bounds. In this work, we show that concatenation can be successfully replaced by limits on the communication channel capacity. It allows us to re-derive and, in some cases, significantly improve all the previously known results in a simpler manner and apply the Information Causality principle to previously unapproachable Bell scenarios.

`@Article{miklin_information_2021, author = {Miklin, Nikolai and Pawłowski, Marcin}, journal= {Physical {R}eview {L}etters}, title= {Information {Causality} without concatenation}, year = {2021}, issn = {0031-9007, 1079-7114}, month= jun, note = {arXiv: 2101.12710}, number = {22}, pages= {220403}, volume = {126}, abstract = {Information Causality is a physical principle which states that the amount of randomly accessible data over a classical communication channel cannot exceed its capacity, even if the sender and the receiver have access to a source of nonlocal correlations. This principle can be used to bound the nonlocality of quantum mechanics without resorting to its full formalism, with a notable example of reproducing the Tsirelson's bound of the Clauser-Horne-Shimony-Holt inequality. Despite being promising, the latter result found little generalization to other Bell inequalities because of the limitations imposed by the process of concatenation, in which several nonsignaling resources are put together to produce tighter bounds. In this work, we show that concatenation can be successfully replaced by limits on the communication channel capacity. It allows us to re-derive and, in some cases, significantly improve all the previously known results in a simpler manner and apply the Information Causality principle to previously unapproachable Bell scenarios.}, doi= {10.1103/PhysRevLett.126.220403}, keywords = {Quantum Physics}, url= {http://arxiv.org/abs/2101.12710}, urldate= {2021-07-28}, }`

- Wooyeong Song, Youngrong Lim, Hyukjoon Kwon, Gerardo Adesso, Marcin Wieśniak, Marcin Pawłowski, Jaewan Kim, and Jeongho Bang. Quantum secure learning with classical samples.
*Physical Review A*, 103(4):042409, apr 2021. arXiv: 1912.10594 doi:10.1103/PhysRevA.103.042409

[BibTeX] [Abstract] [Download PDF]

Studies addressing the question “Can a learner complete the learning securely?” have recently been spurred from the standpoints of fundamental theory and potential applications. In the relevant context of this question, we present a classical-quantum hybrid sampling protocol and define a security condition that allows only legitimate learners to prepare a finite set of samples that guarantees the success of the learning; the security condition excludes intruders. We do this by combining our security concept with the bound of the so-called probably approximately correct (PAC) learning. We show that while the lower bound on the learning samples guarantees PAC learning, an upper bound can be derived to rule out adversarial learners. Such a secure learning condition is appealing, because it is defined only by the size of samples required for the successful learning and is independent of the algorithm employed. Notably, the security stems from the fundamental quantum no-broadcasting principle. No such condition can thus occur in any classical regime, where learning samples can be copied. Owing to the hybrid architecture, our scheme also offers a practical advantage for implementation in noisy intermediate-scale quantum devices.

`@Article{song_quantum_2021, author = {Song, Wooyeong and Lim, Youngrong and Kwon, Hyukjoon and Adesso, Gerardo and Wieśniak, Marcin and Pawłowski, Marcin and Kim, Jaewan and Bang, Jeongho}, journal= {Physical {R}eview {A}}, title= {Quantum secure learning with classical samples}, year = {2021}, issn = {2469-9926, 2469-9934}, month= apr, note = {arXiv: 1912.10594}, number = {4}, pages= {042409}, volume = {103}, abstract = {Studies addressing the question "Can a learner complete the learning securely?" have recently been spurred from the standpoints of fundamental theory and potential applications. In the relevant context of this question, we present a classical-quantum hybrid sampling protocol and define a security condition that allows only legitimate learners to prepare a finite set of samples that guarantees the success of the learning; the security condition excludes intruders. We do this by combining our security concept with the bound of the so-called probably approximately correct (PAC) learning. We show that while the lower bound on the learning samples guarantees PAC learning, an upper bound can be derived to rule out adversarial learners. Such a secure learning condition is appealing, because it is defined only by the size of samples required for the successful learning and is independent of the algorithm employed. Notably, the security stems from the fundamental quantum no-broadcasting principle. No such condition can thus occur in any classical regime, where learning samples can be copied. Owing to the hybrid architecture, our scheme also offers a practical advantage for implementation in noisy intermediate-scale quantum devices.}, doi= {10.1103/PhysRevA.103.042409}, keywords = {Quantum Physics}, url= {http://arxiv.org/abs/1912.10594}, urldate= {2021-07-28}, }`

- Maciej Stankiewicz, Karol Horodecki, Omer Sakarya, and Danuta Makowiec. Private Weakly-Random Sequences from Human Heart Rate for Quantum Amplification.
*Entropy*, 23(9):1182, sep 2021. doi:10.3390/e23091182

[BibTeX] [Abstract] [Download PDF]

We investigate whether the heart rate can be treated as a semi-random source with the aim of amplification by quantum devices. We use a semi-random source model called $\epsilon$-Santha-Vazirani source, which can be amplified via quantum protocols to obtain fully private random sequence. We analyze time intervals between consecutive heartbeats obtained from Holter electrocardiogram (ECG) recordings of people of different sex and age. We propose several transformations of the original time series into binary sequences. We have performed different statistical randomness tests and estimated quality parameters. We find that the heart can be treated as good enough, and private by its nature, source of randomness, that every human possesses. As such, in principle it can be used as input to quantum device-independent randomness amplification protocols. The properly interpreted $\epsilon$ parameter can potentially serve as a new characteristic of the human’s heart from the perspective of medicine.

`@Article{Stankiewicz2021, author= {Stankiewicz, Maciej and Horodecki, Karol and Sakarya, Omer and Makowiec, Danuta}, journal = {Entropy}, title = {Private {W}eakly-{R}andom {S}equences from {H}uman {H}eart {R}ate for {Q}uantum {A}mplification}, year= {2021}, month = sep, number= {9}, pages = {1182}, volume= {23}, abstract= {We investigate whether the heart rate can be treated as a semi-random source with the aim of amplification by quantum devices. We use a semi-random source model called $\epsilon$-Santha-Vazirani source, which can be amplified via quantum protocols to obtain fully private random sequence. We analyze time intervals between consecutive heartbeats obtained from Holter electrocardiogram (ECG) recordings of people of different sex and age. We propose several transformations of the original time series into binary sequences. We have performed different statistical randomness tests and estimated quality parameters. We find that the heart can be treated as good enough, and private by its nature, source of randomness, that every human possesses. As such, in principle it can be used as input to quantum device-independent randomness amplification protocols. The properly interpreted $\epsilon$ parameter can potentially serve as a new characteristic of the human's heart from the perspective of medicine.}, archiveprefix = {arXiv}, doi = {10.3390/e23091182}, eprint= {2107.14630}, keywords= {Quantum Physics}, primaryclass= {quant-ph}, url = {https://ui.adsabs.harvard.edu/abs/2021Entrp..23.1182S}, }`

- Anubhav Chaturvedi, Máté. Farkas, and Victoria J. Wright. Characterising and bounding the set of quantum behaviours in contextuality scenarios.
*Quantum*, 5:484, 06 2021. doi:10.22331/q-2021-06-29-484

[BibTeX] [Abstract] [Download PDF]

The predictions of quantum theory resist generalised noncontextual explanations. In addition to the foundational relevance of this fact, the particular extent to which quantum theory violates noncontextuality limits available quantum advantage in communication and information processing. In the first part of this work, we formally define contextuality scenarios via prepare-and-measure experiments, along with the polytope of general contextual behaviours containing the set of quantum contextual behaviours. This framework allows us to recover several properties of set of quantum behaviours in these scenarios, including contextuality scenarios and associated noncontextuality inequalities that require for their violation the individual quantum preparation and measurement procedures to be mixed states and unsharp measurements. With the framework in place, we formulate novel semidefinite programming relaxations for bounding these sets of quantum contextual behaviours. Most significantly, to circumvent the inadequacy of pure states and projective measurements in contextuality scenarios, we present a novel unitary operator based semidefinite relaxation technique. We demonstrate the efficacy of these relaxations by obtaining tight upper bounds on the quantum violation of several noncontextuality inequalities and identifying novel maximally contextual quantum strategies. To further illustrate the versatility of these relaxations, we demonstrate $\textitmonogamy of preparation contextuality$ in a tripartite setting, and present a secure semi-device independent quantum key distribution scheme powered by quantum advantage in parity oblivious random access codes.

`@Article{Chaturvedi2021, author= {Anubhav Chaturvedi and Máté Farkas and Victoria J Wright}, journal = {Quantum}, title = {Characterising and bounding the set of quantum behaviours in contextuality scenarios}, year= {2021}, issn= {2521-327X}, month = {06}, pages = {484}, volume= {5}, abstract= {The predictions of quantum theory resist generalised noncontextual explanations. In addition to the foundational relevance of this fact, the particular extent to which quantum theory violates noncontextuality limits available quantum advantage in communication and information processing. In the first part of this work, we formally define contextuality scenarios via prepare-and-measure experiments, along with the polytope of general contextual behaviours containing the set of quantum contextual behaviours. This framework allows us to recover several properties of set of quantum behaviours in these scenarios, including contextuality scenarios and associated noncontextuality inequalities that require for their violation the individual quantum preparation and measurement procedures to be mixed states and unsharp measurements. With the framework in place, we formulate novel semidefinite programming relaxations for bounding these sets of quantum contextual behaviours. Most significantly, to circumvent the inadequacy of pure states and projective measurements in contextuality scenarios, we present a novel unitary operator based semidefinite relaxation technique. We demonstrate the efficacy of these relaxations by obtaining tight upper bounds on the quantum violation of several noncontextuality inequalities and identifying novel maximally contextual quantum strategies. To further illustrate the versatility of these relaxations, we demonstrate $\textit{monogamy of preparation contextuality}$ in a tripartite setting, and present a secure semi-device independent quantum key distribution scheme powered by quantum advantage in parity oblivious random access codes.}, doi = {10.22331/q-2021-06-29-484}, groups= {Sainz}, publisher = {Verein zur Förderung des Open Access Publizierens in den Quantenwissenschaften}, url = {https://quantum-journal.org/papers/q-2021-06-29-484/pdf/}, }`

- Wooyeong Song, Marcin Wieśniak, Nana Liu, Marcin Pawłowski, Jinhyoung Lee, Jaewan Kim, and Jeongho Bang. Tangible reduction in learning sample complexity with large classical samples and small quantum system.
*Quantum Information Processing*, 20(8):Paper No. 275, 18, 2021. doi:10.1007/s11128-021-03217-7

[BibTeX] [Download PDF]`@Article{Song2021, author = {Song, Wooyeong and Wieśniak, Marcin and Liu, Nana and Pawłowski, Marcin and Lee, Jinhyoung and Kim, Jaewan and Bang, Jeongho}, journal= {Quantum {I}nformation {P}rocessing}, title= {Tangible reduction in learning sample complexity with large classical samples and small quantum system}, year = {2021}, issn = {1570-0755}, number = {8}, pages= {Paper No. 275, 18}, volume = {20}, doi= {10.1007/s11128-021-03217-7}, keywords = {81P68}, mrnumber = {4303621}, url= {https://link.springer.com/content/pdf/10.1007/s11128-021-03217-7.pdf}, }`

- Gniewomir Sarbicki, Giovanni Scala, and Dariusz Chru’sci’nski. Detection Power of Separability Criteria Based on a Correlation Tensor: A Case Study.
*Open Systems &Information Dynamics*, 28(02), jun 2021. doi:10.1142/S1230161221500104

[BibTeX]`@Article{Sarbicki2021, author= {Gniewomir Sarbicki and Giovanni Scala and Dariusz Chru{\'{s}}ci{\'{n}}ski}, journal = {Open Systems {\&}Information Dynamics}, title = {Detection Power of Separability Criteria Based on a Correlation Tensor: A Case Study}, year= {2021}, month = jun, number= {02}, volume= {28}, doi = {10.1142/S1230161221500104}, publisher = {World Scientific Pub Co Pte Ltd}, }`

- Giovanni Scala, Karolina Słowik, Paolo Facchi, Saverio Pascazio, and Francesco V. Pepe. Beyond the Rabi model: Light interactions with polar atomic systems in a cavity.
*Phys. Rev. A*, 104:013722, Jul 2021. doi:10.1103/PhysRevA.104.013722

[BibTeX] [Download PDF]`@article{PhysRevA.104.013722, title = {Beyond the Rabi model: Light interactions with polar atomic systems in a cavity}, author = {Scala, Giovanni and S\l{}owik, Karolina and Facchi, Paolo and Pascazio, Saverio and Pepe, Francesco V.}, journal = {Phys. Rev. A}, volume = {104}, issue = {1}, pages = {013722}, numpages = {11}, year = {2021}, month = Jul, publisher = {American Physical Society}, doi = {10.1103/PhysRevA.104.013722}, url = {https://link.aps.org/doi/10.1103/PhysRevA.104.013722} }`

### 2020

- Karol Horodecki and Maciej Stankiewicz. Semi-device-independent quantum money.
*New Journal of Physics*, 22(2):023007, feb 2020. doi:10.1088/1367-2630/ab6872

[BibTeX] [Download PDF]`@Article{horodecki_semi-device-independent_2020, author= {Horodecki, Karol and Stankiewicz, Maciej}, journal = {New {J}ournal of {P}hysics}, title = {Semi-device-independent quantum money}, year= {2020}, issn= {1367-2630}, month = feb, number= {2}, pages = {023007}, volume= {22}, doi = {10.1088/1367-2630/ab6872}, url = {https://iopscience.iop.org/article/10.1088/1367-2630/ab6872}, urldate = {2020-04-22}, }`

- Marcin Pawłowski. Entropy in Foundations of Quantum Physics.
*Entropy*, 22(3):371, mar 2020. doi:10.3390/e22030371

[BibTeX] [Abstract] [Download PDF]

Entropy can be used in studies on foundations of quantum physics in many different ways, each of them using different properties of this mathematical object […]

`@article{pawlowski_entropy_2020, title = {Entropy in {Foundations} of {Quantum} {Physics}}, volume = {22}, issn = {1099-4300}, url = {https://www.mdpi.com/1099-4300/22/3/371}, doi = {10.3390/e22030371}, abstract = {Entropy can be used in studies on foundations of quantum physics in many different ways, each of them using different properties of this mathematical object [...]}, language = {en}, number = {3}, urldate = {2020-04-22}, journal = {Entropy}, author = {Pawłowski, Marcin}, month = mar, year = {2020}, pages = {371}, }`

- 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}, }`

- 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):032621, 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):062420, 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}, }`

- Anubhav Chaturvedi and Debashis Saha. Quantum prescriptions are more ontologically distinct than they are operationally distinguishable.
*Quantum*, 4:345, oct 2020. doi:10.22331/q-2020-10-21-345

[BibTeX] [Abstract] [Download PDF]

Based on an intuitive generalization of the Leibniz principle of `the identity of indiscernibles’, we introduce a novel ontological notion of classicality, called bounded ontological distinctness. Formulated as a principle, bounded ontological distinctness equates the distinguishability of a set of operational physical entities to the distinctness of their ontological counterparts. Employing three instances of two-dimensional quantum preparations, we demonstrate the violation of bounded ontological distinctness or excess ontological distinctness of quantum preparations, without invoking any additional assumptions. Moreover, our methodology enables the inference of tight lower bounds on the extent of excess ontological distinctness of quantum preparations. Similarly, we demonstrate excess ontological distinctness of quantum transformations, using three two-dimensional unitary transformations. However, to demonstrate excess ontological distinctness of quantum measurements, an additional assumption such as outcome determinism or bounded ontological distinctness of preparations is required. Moreover, we show that quantum violations of other well-known ontological principles implicate quantum excess ontological distinctness. Finally, to showcase the operational vitality of excess ontological distinctness, we introduce two distinct classes of communication tasks powered by excess ontological distinctness.

`@article{chaturvedi_quantum_2020, title = {Quantum prescriptions are more ontologically distinct than they are operationally distinguishable}, volume = {4}, issn = {2521-327X}, url = {https://quantum-journal.org/papers/q-2020-10-21-345/}, doi = {10.22331/q-2020-10-21-345}, abstract = {Based on an intuitive generalization of the Leibniz principle of `the identity of indiscernibles', we introduce a novel ontological notion of classicality, called bounded ontological distinctness. Formulated as a principle, bounded ontological distinctness equates the distinguishability of a set of operational physical entities to the distinctness of their ontological counterparts. Employing three instances of two-dimensional quantum preparations, we demonstrate the violation of bounded ontological distinctness or excess ontological distinctness of quantum preparations, without invoking any additional assumptions. Moreover, our methodology enables the inference of tight lower bounds on the extent of excess ontological distinctness of quantum preparations. Similarly, we demonstrate excess ontological distinctness of quantum transformations, using three two-dimensional unitary transformations. However, to demonstrate excess ontological distinctness of quantum measurements, an additional assumption such as outcome determinism or bounded ontological distinctness of preparations is required. Moreover, we show that quantum violations of other well-known ontological principles implicate quantum excess ontological distinctness. Finally, to showcase the operational vitality of excess ontological distinctness, we introduce two distinct classes of communication tasks powered by excess ontological distinctness.}, language = {en}, urldate = {2021-05-10}, journal = {Quantum}, author = {Chaturvedi, Anubhav and Saha, Debashis}, month = oct, year = {2020}, pages = {345}, }`

### 2019

- Piotr Mironowicz and Marcin Pawłowski. Experimentally feasible semi-device-independent certification of four-outcome positive-operator-valued measurements.
*Physical Review A*, 100(3):030301, 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} }`

## arXiv preprints

### 2022

- Nikolai Miklin, Anubhav Chaturvedi, Mohamed Bourennane, Marcin Pawłowski, and Adán Cabello. Exponentially decreasing critical detection efficiency for any Bell inequality. 2022. doi:10.48550/ARXIV.2204.11726

[BibTeX] [Download PDF]`@misc{https://doi.org/10.48550/arxiv.2204.11726, doi = {10.48550/ARXIV.2204.11726}, url = {https://arxiv.org/abs/2204.11726}, author = {Miklin, Nikolai and Chaturvedi, Anubhav and Bourennane, Mohamed and Pawłowski, Marcin and Cabello, Adán}, keywords = {Quantum Physics (quant-ph), FOS: Physical sciences, FOS: Physical sciences}, title = {Exponentially decreasing critical detection efficiency for any Bell inequality}, publisher = {arXiv}, year = {2022}, copyright = {arXiv.org perpetual, non-exclusive license} }`

- Gianlorenzo Massaro, Giovanni Scala, Milena D’Angelo, and Francesco V. Pepe. Comparative analysis of signal-to-noise ratio in correlation plenoptic imaging architectures. , jun 2022.

[BibTeX] [Abstract]

Correlation plenoptic imaging (CPI) is a scanning-free diffraction-limited 3D optical imaging technique exploiting the peculiar properties of correlated light sources. CPI has been further extended to samples of interest to microscopy, such as fluorescent or scattering objects, in a modified architecture named correlation light-field microscopy (CLM). Interestingly, experiments have shown that the noise performances of CLM are significantly improved over the original CPI scheme, leading to better images and faster acquisition. In this work, we provide a theoretical foundation to such advantage by investigating the properties of both the signal-to-noise and the signal-to-background ratios of CLM and the original CPI setup.

`@Article{Massaro2022, author = {Gianlorenzo Massaro and Giovanni Scala and Milena D'Angelo and Francesco V. Pepe}, title = {Comparative analysis of signal-to-noise ratio in correlation plenoptic imaging architectures}, year = {2022}, month = jun, abstract = {Correlation plenoptic imaging (CPI) is a scanning-free diffraction-limited 3D optical imaging technique exploiting the peculiar properties of correlated light sources. CPI has been further extended to samples of interest to microscopy, such as fluorescent or scattering objects, in a modified architecture named correlation light-field microscopy (CLM). Interestingly, experiments have shown that the noise performances of CLM are significantly improved over the original CPI scheme, leading to better images and faster acquisition. In this work, we provide a theoretical foundation to such advantage by investigating the properties of both the signal-to-noise and the signal-to-background ratios of CLM and the original CPI setup.}, archiveprefix = {arXiv}, eprint = {2206.13412}, file = {:http\://arxiv.org/pdf/2206.13412v1:PDF}, keywords = {physics.optics, quant-ph}, primaryclass = {physics.optics}, }`

- Lorenzo Catani, Matthew Leifer, Giovanni Scala, David Schmid, and Robert W. Spekkens. What is nonclassical about uncertainty relations?. , jul 2022.

[BibTeX] [Abstract]

Uncertainty relations express limits on the extent to which the outcomes of distinct measurements on a single state can be made jointly predictable. The existence of nontrivial uncertainty relations in quantum theory is generally considered to be a way in which it entails a departure from the classical worldview. However, this view is undermined by the fact that there exist operational theories which exhibit nontrivial uncertainty relations but which are consistent with the classical worldview insofar as they admit of a generalized-noncontextual ontological model. This prompts the question of what aspects of uncertainty relations, if any, cannot be realized in this way and so constitute evidence of genuine nonclassicality. We here consider uncertainty relations describing the tradeoff between the predictability of a pair of binary-outcome measurements (e.g., measurements of Pauli X and Pauli Z observables in quantum theory). We show that, for a class of theories satisfying a particular symmetry property, the functional form of this predictability tradeoff is constrained by noncontextuality to be below a linear curve. Because qubit quantum theory has the relevant symmetry property, the fact that it has a quadratic tradeoff between these predictabilities is a violation of this noncontextual bound, and therefore constitutes an example of how the functional form of an uncertainty relation can witness contextuality. We also deduce the implications for a selected group of operational foils to quantum theory and consider the generalization to three measurements.

`@Article{Catani2022, author = {Lorenzo Catani and Matthew Leifer and Giovanni Scala and David Schmid and Robert W. Spekkens}, title = {What is nonclassical about uncertainty relations?}, year = {2022}, month = jul, abstract = {Uncertainty relations express limits on the extent to which the outcomes of distinct measurements on a single state can be made jointly predictable. The existence of nontrivial uncertainty relations in quantum theory is generally considered to be a way in which it entails a departure from the classical worldview. However, this view is undermined by the fact that there exist operational theories which exhibit nontrivial uncertainty relations but which are consistent with the classical worldview insofar as they admit of a generalized-noncontextual ontological model. This prompts the question of what aspects of uncertainty relations, if any, cannot be realized in this way and so constitute evidence of genuine nonclassicality. We here consider uncertainty relations describing the tradeoff between the predictability of a pair of binary-outcome measurements (e.g., measurements of Pauli X and Pauli Z observables in quantum theory). We show that, for a class of theories satisfying a particular symmetry property, the functional form of this predictability tradeoff is constrained by noncontextuality to be below a linear curve. Because qubit quantum theory has the relevant symmetry property, the fact that it has a quadratic tradeoff between these predictabilities is a violation of this noncontextual bound, and therefore constitutes an example of how the functional form of an uncertainty relation can witness contextuality. We also deduce the implications for a selected group of operational foils to quantum theory and consider the generalization to three measurements.}, archiveprefix = {arXiv}, eprint = {2207.11779}, file = {:http\://arxiv.org/pdf/2207.11779v1:PDF}, keywords = {quant-ph}, primaryclass = {quant-ph}, }`

- Lorenzo Catani, Matthew Leifer, Giovanni Scala, David Schmid, and Robert W. Spekkens. What aspects of the phenomenology of interference witness nonclassicality?. , nov 2022.

[BibTeX] [Abstract]

Interference phenomena are often claimed to resist classical explanation. However, such claims are undermined by the fact that the specific aspects of the phenomenology upon which they are based can in fact be reproduced in a noncontextual ontological model [Catani et al. arXiv:2111.13727]. This raises the question of what other aspects of the phenomenology of interference do in fact resist classical explanation. We answer this question by demonstrating that the most basic quantum wave-particle duality relation, which expresses the precise trade-off between path distinguishability and fringe visibility, cannot be reproduced in any noncontextual model. We do this by showing that it is a specific type of uncertainty relation, and then leveraging a recent result establishing that noncontextuality restricts the functional form of this uncertainty relation [Catani et al. arXiv:2207.11779]. Finally, we discuss what sorts of interferometric experiment can demonstrate contextuality via the wave-particle duality relation.

`@Article{Catani2022a, author = {Lorenzo Catani and Matthew Leifer and Giovanni Scala and David Schmid and Robert W. Spekkens}, title = {What aspects of the phenomenology of interference witness nonclassicality?}, year = {2022}, month = nov, abstract = {Interference phenomena are often claimed to resist classical explanation. However, such claims are undermined by the fact that the specific aspects of the phenomenology upon which they are based can in fact be reproduced in a noncontextual ontological model [Catani et al. arXiv:2111.13727]. This raises the question of what other aspects of the phenomenology of interference do in fact resist classical explanation. We answer this question by demonstrating that the most basic quantum wave-particle duality relation, which expresses the precise trade-off between path distinguishability and fringe visibility, cannot be reproduced in any noncontextual model. We do this by showing that it is a specific type of uncertainty relation, and then leveraging a recent result establishing that noncontextuality restricts the functional form of this uncertainty relation [Catani et al. arXiv:2207.11779]. Finally, we discuss what sorts of interferometric experiment can demonstrate contextuality via the wave-particle duality relation.}, archiveprefix = {arXiv}, eprint = {2211.09850}, file = {:http\://arxiv.org/pdf/2211.09850v1:PDF}, keywords = {quant-ph}, primaryclass = {quant-ph}, }`

- Karol Horodecki, Jingfang Zhou, Maciej Stankiewicz, Roberto Salazar, Paweł Horodecki, Robert Raussendorf, Ryszard Horodecki, Ravishankar Ramanathan, and Emily Tyhurst. The rank of contextuality. , 2022. doi:10.48550/ARXIV.2205.10307

[BibTeX] [Download PDF]`@article{https://doi.org/10.48550/arxiv.2205.10307, doi = {10.48550/ARXIV.2205.10307}, url = {https://arxiv.org/abs/2205.10307}, author = {Horodecki, Karol and Zhou, Jingfang and Stankiewicz, Maciej and Salazar, Roberto and Horodecki, Paweł and Raussendorf, Robert and Horodecki, Ryszard and Ramanathan, Ravishankar and Tyhurst, Emily}, keywords = {Quantum Physics (quant-ph), FOS: Physical sciences, FOS: Physical sciences}, title = {The rank of contextuality}, publisher = {arXiv}, year = {2022}, copyright = {arXiv.org perpetual, non-exclusive license} }`

- Karol Horodecki, Jingfang Zhou, Maciej Stankiewicz, Roberto Salazar, Paweł Horodecki, Robert Raussendorf, Ryszard Horodecki, Ravishankar Ramanathan, and Emily Tyhurst. The rank of contextuality. , may 2022. acknowledgement for ICTQT IRAP included doi:10.48550/ARXIV.2205.10307

[BibTeX] [Download PDF]`@article{arxiv_Horodecki_The_2022, doi = {10.48550/ARXIV.2205.10307}, url = {https://arxiv.org/abs/2205.10307}, author = {Horodecki, Karol and Zhou, Jingfang and Stankiewicz, Maciej and Salazar, Roberto and Horodecki, Paweł and Raussendorf, Robert and Horodecki, Ryszard and Ramanathan, Ravishankar and Tyhurst, Emily}, keywords = {Quantum Physics (quant-ph), FOS: Physical sciences, FOS: Physical sciences}, title = {The rank of contextuality}, note= {acknowledgement for ICTQT IRAP included}, publisher = {arXiv}, year = {2022}, copyright = {arXiv.org perpetual, non-exclusive license}, month = may, note = {arXiv: 2205.10307}, groups = {Pawel_H}, }`

- Piotr Mironowicz. Quantum security and theory of decoherence.
*arXiv preprint arXiv:2205.12927*, 2022.

[BibTeX]`@article{mironowicz2022quantum, title={Quantum security and theory of decoherence}, author={Mironowicz, Piotr}, journal={arXiv preprint arXiv:2205.12927}, year={2022} }`

- Piotr Mironowicz. Entangled Rendezvous: A Possible Application of Bell Non-Locality For Mobile Agents on Networks.
*arXiv preprint arXiv:2207.14404*, 2022.

[BibTeX]`@article{mironowicz2022entangled, title={Entangled Rendezvous: A Possible Application of Bell Non-Locality For Mobile Agents on Networks}, author={Mironowicz, Piotr}, journal={arXiv preprint arXiv:2207.14404}, year={2022} }`

### 2021

- Mariami Gachechiladze, Bartłomiej Bąk, Marcin Pawłowski, and Nikolai Miklin. Quantum Bell inequalities from Information Causality — tight for Macroscopic Locality.
*arXiv:2103.05029 [quant-ph]*, mar 2021. arXiv: 2103.05029

[BibTeX] [Abstract] [Download PDF]

Quantum generalizations of Bell inequalities are analytical expressions of correlations observed in the Bell experiment that are used to explain or estimate the set of correlations that quantum theory allows. Unlike standard Bell inequalities, their quantum analogs are rare in the literature, as no known algorithm can be used to find them systematically. In this work, we present a family of quantum Bell inequalities in scenarios where the number of settings or outcomes can be arbitrarily high. We derive these inequalities from the principle of Information Causality, and thus, we do not assume the formalism of quantum mechanics. Considering the symmetries of the derived inequalities, we show that the latter give the necessary and sufficient condition for the correlations to comply with Macroscopic Locality. As a result, we conclude that the principle of Information Causality is strictly stronger than the principle of Macroscopic Locality in the subspace defined by these symmetries.

`@article{gachechiladze_quantum_2021, title = {Quantum {Bell} inequalities from {Information} {Causality} -- tight for {Macroscopic} {Locality}}, url = {http://arxiv.org/abs/2103.05029}, abstract = {Quantum generalizations of Bell inequalities are analytical expressions of correlations observed in the Bell experiment that are used to explain or estimate the set of correlations that quantum theory allows. Unlike standard Bell inequalities, their quantum analogs are rare in the literature, as no known algorithm can be used to find them systematically. In this work, we present a family of quantum Bell inequalities in scenarios where the number of settings or outcomes can be arbitrarily high. We derive these inequalities from the principle of Information Causality, and thus, we do not assume the formalism of quantum mechanics. Considering the symmetries of the derived inequalities, we show that the latter give the necessary and sufficient condition for the correlations to comply with Macroscopic Locality. As a result, we conclude that the principle of Information Causality is strictly stronger than the principle of Macroscopic Locality in the subspace defined by these symmetries.}, urldate = {2021-07-28}, journal = {arXiv:2103.05029 [quant-ph]}, author = {Gachechiladze, Mariami and Bąk, Bartłomiej and Pawłowski, Marcin and Miklin, Nikolai}, month = mar, year = {2021}, note = {arXiv: 2103.05029}, keywords = {Quantum Physics}, }`

- Anubhav Chaturvedi, Marcin Pawłowski, and Debashis Saha. Quantum description of reality is empirically incomplete.
*arXiv e-prints*, pages arXiv:2110.13124, oct 2021.

[BibTeX] [Abstract] [Download PDF]

Empirical falsifiability of the predictions of physical theories is the cornerstone of the scientific method. Physical theories attribute empirically falsifiable operational properties to sets of physical preparations. A theory is said to be empirically complete if such properties allow for a not fine-tuned realist explanation, as properties of underlying probability distributions over states of reality. Such theories satisfy a family of equalities among fundamental operational properties, characterized exclusively by the number of preparations. Quantum preparations deviate from these equalities, and the maximal quantum deviation increases with the number of preparations. These deviations not only signify the incompleteness of the operational quantum formalism, but they simultaneously imply quantum over classical advantage in suitably constrained one-way communication tasks, highlighting the delicate interplay between the two.

`@Article{Chaturvedi2021_arXiv, author = {Chaturvedi, Anubhav and Paw{\l}owski, Marcin and Saha, Debashis}, journal = {arXiv e-prints}, title = {Quantum description of reality is empirically incomplete}, year = {2021}, month = oct, pages = {arXiv:2110.13124}, abstract = {Empirical falsifiability of the predictions of physical theories is the cornerstone of the scientific method. Physical theories attribute empirically falsifiable operational properties to sets of physical preparations. A theory is said to be empirically complete if such properties allow for a not fine-tuned realist explanation, as properties of underlying probability distributions over states of reality. Such theories satisfy a family of equalities among fundamental operational properties, characterized exclusively by the number of preparations. Quantum preparations deviate from these equalities, and the maximal quantum deviation increases with the number of preparations. These deviations not only signify the incompleteness of the operational quantum formalism, but they simultaneously imply quantum over classical advantage in suitably constrained one-way communication tasks, highlighting the delicate interplay between the two.}, archiveprefix = {arXiv}, eid = {arXiv:2110.13124}, eprint = {2110.13124}, keywords = {Quantum Physics}, primaryclass = {quant-ph}, url = {https://ui.adsabs.harvard.edu/abs/2021arXiv211013124C}, }`

### 2020

- Anubhav Chaturvedi, Máté. Farkas, and Victoria J. Wright. Characterising and bounding the set of quantum behaviours in contextuality scenarios.
*arXiv:2010.05853 [quant-ph]*, 2020. arXiv:2010.05853 [quant-ph]

[BibTeX]`@article{chaturvedi2020characterising, title={Characterising and bounding the set of quantum behaviours in contextuality scenarios}, author={Chaturvedi, Anubhav and Farkas, M{\'a}t{\'e} and Wright, Victoria J}, journal={arXiv:2010.05853 [quant-ph]}, year={2020}, note={arXiv:2010.05853 [quant-ph]} }`

- Wooyeong Song, Marcin Wieśniak, Nana Liu, Marcin Pawłowski, Jinhyoung Lee, Jaewan Kim, and Jeongho Bang. Tangible Reduction of Sample Complexity with Large Classical Samples and Small Quantum System.
*arXiv:1905.05751 [quant-ph]*, jun 2020. arXiv: 1905.05751

[BibTeX] [Abstract] [Download PDF]

Quantum computation requires large classical datasets to be embedded into quantum states in order to exploit quantum parallelism. However, this embedding requires considerable resources. It would therefore be desirable to avoid it, if possible, for noisy intermediate-scale quantum (NISQ) implementation. Accordingly, we consider a classical-quantum hybrid architecture, which allows large classical input data, with a relatively small-scale quantum system. This hybrid architecture is used to implement an oracle. It is shown that in the presence of noise in the hybrid oracle, the effects of internal noise can cancel each other out and thereby improve the query success rate. It is also shown that such an immunity of the hybrid oracle to noise directly and tangibly reduces the sample complexity in the probably-approximately-correct learning framework. This NISQ-compatible learning advantage is attributed to the oracle’s ability to handle large input features.

`@article{song_tangible_2020, title = {Tangible {Reduction} of {Sample} {Complexity} with {Large} {Classical} {Samples} and {Small} {Quantum} {System}}, url = {http://arxiv.org/abs/1905.05751}, abstract = {Quantum computation requires large classical datasets to be embedded into quantum states in order to exploit quantum parallelism. However, this embedding requires considerable resources. It would therefore be desirable to avoid it, if possible, for noisy intermediate-scale quantum (NISQ) implementation. Accordingly, we consider a classical-quantum hybrid architecture, which allows large classical input data, with a relatively small-scale quantum system. This hybrid architecture is used to implement an oracle. It is shown that in the presence of noise in the hybrid oracle, the effects of internal noise can cancel each other out and thereby improve the query success rate. It is also shown that such an immunity of the hybrid oracle to noise directly and tangibly reduces the sample complexity in the probably-approximately-correct learning framework. This NISQ-compatible learning advantage is attributed to the oracle's ability to handle large input features.}, urldate = {2021-07-28}, journal = {arXiv:1905.05751 [quant-ph]}, author = {Song, Wooyeong and Wieśniak, Marcin and Liu, Nana and Pawłowski, Marcin and Lee, Jinhyoung and Kim, Jaewan and Bang, Jeongho}, month = jun, year = {2020}, note = {arXiv: 1905.05751}, keywords = {Quantum Physics}, }`

- Edgar A. Aguilar, Hanna Wojewódka-Ściążko, Maciej Stankiewicz, Christopher Perry, Piotr Ćwikliński, Andrzej Grudka, Karol Horodecki, and Michał Horodecki. Thermal Operations in general are not memoryless. , 2020. doi:10.48550/ARXIV.2009.03110

[BibTeX] [Download PDF]`@article{https://doi.org/10.48550/arxiv.2009.03110, doi = {10.48550/ARXIV.2009.03110}, url = {https://arxiv.org/abs/2009.03110}, author = {Aguilar, Edgar A. and Wojewódka-Ściążko, Hanna and Stankiewicz, Maciej and Perry, Christopher and Ćwikliński, Piotr and Grudka, Andrzej and Horodecki, Karol and Horodecki, Michał}, keywords = {Quantum Physics (quant-ph), FOS: Physical sciences, FOS: Physical sciences}, title = {Thermal Operations in general are not memoryless}, publisher = {arXiv}, year = {2020}, copyright = {arXiv.org perpetual, non-exclusive license} }`

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__Keywords:__ quantum cryptography, random number generation, cryptoanalysis, quantum communication, quantum key distribution, device-independent protocols.