BRANCIARD Cyril

BRANCIARD Cyril

E-mail : cyril.branciard@neel.cnrs.fr
Phone : +33(0)4 56 38 70 60

Postal address :
Institut Néel, CNRS/UJF
25, avenue des Martyrs - BP 166
Fr-38042 Grenoble Cedex 9


Research activities :

Theoretical research in Quantum Foundations and Quantum Information Science : quantum non-locality, Bell inequalities, quantum causality, generalized probabilistic theories, uncertainty principle, quantum cryptography, applications in quantum optics

I joined the Institut Néel in September 2014, with a postdoctoral position funded by both an International Incoming Marie Curie Fellowship (IFF) of the European Commission and by a ‘Retour Postdoctorants’ Fellowship of the French National Research Agency (ANR). In 2016 I obtained a permanent CNRS position as a “Chargé de Recherche 1ère classe” (CR1).




       » Publications        » Participation to conferences




Publications :

( » Links to my arXiv e-prints ; to my ORCID and Google Scholar profiles)


    E-prints :


  1. M. Proietti, A. Pickston, F. Graffitti, P. Barrow, D. Kundys, C. Branciard, M. Ringbauer, and A. Fedrizzi,
    Experimental rejection of observer-independence in the quantum world,
    arXiv:1902.05080 (quant-ph).

         » Media coverage : New Scientist, MIT Technology Review, Futurism, Science Alert, Live Science, Tech Times, Dailynous, Computing, The Times, Express, The Independent, Fox News (!), The Sun, Trust My Science (fr), Ulyces (fr), Kronen Zeitung (de), etc. (Just google Wigner + name of one of the authors.)

  2. A. A. Abbott, J. Wechs, D. Horsman, M. Mhalla, and C. Branciard,
    Communication through coherent control of quantum channels,
    arXiv:1810.09826 (quant-ph).


  3. A. A. Abbott, R. Silva, J. Wechs, N. Brunner, and C. Branciard,
    Anomalous Weak Values Without Post-Selection,
    arXiv:1805.09364 (quant-ph).


    Published in peer-reviewed scientific journals :


  4. B. Demirel, S. Sponar, A. A. Abbott, C. Branciard, and Y. Hasegawa,
    Experimental test of an entropic measurement uncertainty relation for arbitrary qubit observables,
    New Journal of Physics 21, 013038 (2018).


  5. J. Wechs, A. A. Abbott, and C. Branciard,
    On the definition and characterisation of multipartite causal (non)separability,
    New Journal of Physics 21, 013027 (2018).


  6. K. Goswami, C. Giarmatzi, M. Kewming, F. Costa, C. Branciard, J. Romero, and A. G. White,
    Indefinite Causal Order in a Quantum Switch,
    Physical Review Letters 121, 090503 (2018)  —  Editors’ Suggestion.

         » Press release      » Media coverage : Science, Physics World, ScienceNews, Live Science, Media Inaf (it)

       » Selected in the Top 10 Physics World 2018 Breakthroughs of the Year

  7. V. Pozsgay, F. Hirsch, C. Branciard, and N. Brunner,
    Covariance Bell inequalities,
    Physical Review A 96, 062128 (2017).


  8. A. A. Abbott, J. Wechs, F. Costa, and C. Branciard,
    Genuinely Multipartite Noncausality,
    Quantum 1, 39 (2017).


  9. N. Miklin, A. A. Abbott, C. Branciard, R. Chaves, and C. Budroni,
    The entropic approach to causal correlations,
    New Journal of Physics 19, 113041 (2017).


  10. D. J. Saunders, A. J. Bennet, C. Branciard, and G. J. Pryde,
    Experimental demonstration of non-bilocal quantum correlations,
    Science Advances 3, e1602743 (2017).


  11. A. A. Abbott and C. Branciard,
    Noise and disturbance of qubit measurements : An information-theoretic characterization,
    Physical Review A 94, 062110 (2016).


  12. A. A. Abbott, C. Giarmatzi, F. Costa, and C. Branciard,
    Multipartite causal correlations : Polytopes and inequalities,
    Physical Review A 94, 032131 (2016).


  13. C. Branciard,
    Witnesses of causal nonseparability : an introduction and a few case studies,
    Scientific Reports 6, 26018 (2016).


  14. A. A. Abbott, P.-L. Alzieu, M. J. W. Hall, and C. Branciard,
    Tight State-Independent Uncertainty Relations for Qubits,
    Mathematics 4(1), 8 (2016).


  15. D. Rosset, C. Branciard, T. J. Barnea, G. Pütz, N. Brunner, and N. Gisin,
    Nonlinear Bell inequalities tailored for quantum networks,
    Physical Review Letters 116, 010403 (2016).


  16. C. Branciard, M. Araújo, A. Feix, F. Costa, and Č. Brukner,
    The simplest causal inequalities and their violation,
    New Journal of Physics 18, 013008 (2016).


  17. M. Araújo, C. Branciard, F. Costa, A. Feix, C. Giarmatzi, and Č. Brukner,
    Witnessing causal nonseparability,
    New Journal of Physics 17, 102001 (2015) (Fast Track Communication).

         » NJP Perspective      » Media coverage : Phys.org, Motherboard, Futurism

  18. M. Ringbauer, B. Duffus, C. Branciard, E. G. Cavalcanti, A. G. White, and A. Fedrizzi,
    Measurements on the reality of the wave function,
    Nature Physics 11, 249 (2015).

         » Press release (UQ), (USyd)      » Media coverage : Nature News Feature, New Scientist, FQXi Podcast [mp3], Phys.org, The New York Times, The Register, Motherboard, The Conversation, Australasian Science, IFLScience, Mostly Quantum, Wiener Zeitung (de), science.orf.at (de), WirtschaftsBlatt (de), futurezone (de), il Bo (it), lenta.ru (1) (ru), lenta.ru (2) (ru), OFFNews (bu)

  19. C. Branciard,
    How ψ-Epistemic Models Fail at Explaining the Indistinguishability of Quantum States,
    Physical Review Letters 113, 020409 (2014).


  20. J. A. Slater, C. Branciard, N. Brunner, and W. Tittel,
    Device-dependent and device-independent quantum key distribution without a shared reference frame,
    New Journal of Physics 16, 043002 (2014).


  21. C. Branciard,
    Deriving tight error-trade-off relations for approximate joint measurements of incompatible quantum observables,
    Physical Review A 89, 022124 (2014).


  22. M. Ringbauer, D. N. Biggerstaff, M. A. Broome, A. Fedrizzi, C. Branciard, and A. G. White,
    Experimental Joint Quantum Measurements with Minimum Uncertainty,
    Physical Review Letters 112, 020401 (2014)  —  Editors’ Suggestion.

         » Press release      » Media coverage : La Recherche (fr), Phys.org, Australasian Science, Wiener Zeitung (de)

  23. C. Branciard,
    Bell’s local causality, Leggett’s crypto-nonlocality, and quantum separability are genuinely different concepts,
    Physical Review A 88, 042113 (2013).


  24. D. Rosset, C. Branciard, N. Gisin, and Y.-C. Liang,
    Entangled states cannot be classically simulated in generalized Bell experiments with quantum inputs,
    New Journal of Physics 15, 053025 (2013).


  25. C. Branciard,
    Error-tradeoff and error-disturbance relations for incompatible quantum measurements,
    Proceedings of the National Academy of Sciences 110, 6742 (2013).

         » Press release      » Media coverage : La Recherche (fr), Phys.org, Australasian Science

  26. C. Branciard, D. Rosset, Y.-C. Liang, and N. Gisin,
    Measurement-Device-Independent Entanglement Witnesses for All Entangled Quantum States,
    Physical Review Letters 110, 060405 (2013)  —  Editors’ Suggestion.


  27. C. Branciard, N. Brunner, H. Buhrman, R. Cleve, N. Gisin, S. Portmann, D. Rosset, and M. Szegedy,
    Classical simulation of entanglement swapping with bounded communication,
    Physical Review Letters 109, 100401 (2012).


  28. A. J. Bennet, D. A. Evans, D. J. Saunders, C. Branciard, E. G. Cavalcanti, H. M. Wiseman, and G. J. Pryde,
    Arbitrarily Loss-Tolerant Einstein-Podolsky-Rosen Steering Allowing a Demonstration over 1 km of Optical Fiber with No Detection Loophole,
    Physical Review X 2, 031003 (2012).


  29. S. Portmann, C. Branciard, and N. Gisin,
    Local content of all pure two-qubit states,
    Physical Review A 86, 012104 (2012).


  30. P. Shadbolt, T. Vértesi, Y.-C. Liang, C. Branciard, N. Brunner, and J. L. O’Brien,
    Guaranteed violation of a Bell inequality without aligned reference frames or calibrated devices,
    Scientific Reports 2, 470 (2012).


  31. C. Branciard, D. Rosset, N. Gisin, and S. Pironio,
    Bilocal versus non-bilocal correlations in entanglement swapping experiments,
    Physical Review A 85, 032119 (2012).


  32. J.-D. Bancal, C. Branciard, N. Brunner, N. Gisin, and Y.-C. Liang,
    A framework for the study of symmetric full-correlation Bell-like inequalities,
    Journal of Physics A : Mathematical and Theoretical 45, 125301 (2012).


  33. D. H. Smith, G. Gillett, M. P. de Almeida, C. Branciard, A. Fedrizzi, T. J. Weinhold, A. Lita, B. Calkins, T. Gerrits, H. M. Wiseman, S. W. Nam, and A. G. White,
    Conclusive quantum steering with superconducting transition-edge sensors,
    Nature Communications 3, 625 (2012).

         » Press release

  34. C. Branciard, E. G. Cavalcanti, S. P. Walborn, V. Scarani, and H. M. Wiseman,
    One-sided Device-Independent Quantum Key Distribution : Security, feasibility, and the connection with steering,
    Physical Review A 85, 010301(R) (2012).


  35. C. Branciard and N. Gisin,
    Quantifying the Nonlocality of Greenberger-Horne-Zeilinger Quantum Correlations by a Bounded Communication Simulation Protocol,
    Physical Review Letters 107, 020401 (2011).


  36. C. Branciard,
    Detection loophole in Bell experiments : How postselection modifies the requirements to observe nonlocality,
    Physical Review A 83, 032123 (2011).


  37. M. Jakobi, C. Simon, N. Gisin, J.-D. Bancal, C. Branciard, N. Walenta, and H. Zbinden,
    Practical private database queries based on a quantum-key-distribution protocol,
    Physical Review A 83, 022301 (2011).


  38. C. Branciard, H. Zhu, L. Chen, and V. Scarani,
    Evaluation of two different entanglement measures on a bound entangled state,
    Physical Review A 82, 012327 (2010).


  39. C. Branciard, N. Gisin, and S. Pironio,
    Characterizing the Nonlocal Correlations Created via Entanglement Swapping,
    Physical Review Letters 104, 170401 (2010).


  40. C. Branciard, N. Gisin, and V. Scarani,
    Local content of bipartite qubit correlations,
    Physical Review A 81, 022103 (2010).


  41. J.-D. Bancal, C. Branciard, and N. Gisin,
    Simulation of Equatorial von Neumann Measurements on GHZ States Using Nonlocal Resources,
    Advances in Mathematical Physics 2010, 293245 (2010).


  42. P. Sekatski, N. Brunner, C. Branciard, N. Gisin, and C. Simon,
    Towards Quantum Experiments with Human Eyes as Detectors Based on Cloning via Stimulated Emission,
    Physical Review Letters 103, 113601 (2009)  —  Editors’ Suggestion.

         » Media coverage : Nature Photonics Research Highlights, Phys.org, physicsworld.com

  43. J.-D. Bancal, C. Branciard, N. Gisin, and S. Pironio,
    Quantifying Multipartite Nonlocality,
    Physical Review Letters 103, 090503 (2009).


  44. J.-D. Bancal, C. Branciard, N. Brunner, N. Gisin, S. Popescu, and C. Simon,
    Testing a Bell inequality in multipair scenarios,
    Physical Review A 78, 062110 (2008).


  45. N. Brunner, C. Branciard, and N. Gisin,
    Possible entanglement detection with the naked eye,
    Physical Review A 78, 052110 (2008).

         » Media coverage : Nature Research Highlights, New Scientist

  46. D. Salart, A. Baas, C. Branciard, N. Gisin, and H. Zbinden,
    Testing the speed of `spooky action at a distance’,
    Nature 454, 861 (2008).

         » Editor’s Summary, Nature News and Views by T. G. Rudolph, Nature News, Nature Podcast

         » Press release       » Media coverage : Science News, New Scientist (1), New Scientist (2), Phys.org, physicsworld.com, Tribune de Genève (fr) [pdf], swissinfo.ch (fr), Futura-Sciences (fr), Le Courrier (fr) [pdf], Le Journal du Jura (fr) [pdf], Nexus (fr) [pdf], Spiegel Online, Blick (de), Neue Zürcher Zeitung (1) (de), Neue Zürcher Zeitung (2) (de), O Estadão de S. Paulo (pt)

  47. C. Branciard, N. Brunner, N. Gisin, C. Kurtsiefer, A. Lamas-Linares, A. Ling, and V. Scarani,
    Testing quantum correlations versus single-particle properties within Leggett’s model and beyond,
    Nature Physics 4, 681 (2008).

         » Media coverage : Dossiers Pour la Science (fr), Campus magazine (fr)

  48. C. Branciard, N. Gisin, and V. Scarani,
    Upper bounds for the security of two distributed-phase reference protocols of quantum cryptography,
    New Journal of Physics 10, 013031 (2008).


  49. C. Branciard, A. Ling, N. Gisin, C. Kurtsiefer, A. Lamas-Linares, and V. Scarani,
    Experimental Falsification of Leggett’s Nonlocal Variable Model,
    Physical Review Letters 99, 210407 (2007)  —  Editors’ Suggestion.

         » Media coverage : Nature Physics Research Highlights, The Straits Times [pdf]

  50. R. Alléaume, C. Branciard, J. Bouda, T. Debuisschert, M. Dianati, N. Gisin, M. Godfrey, P. Grangier, T. Langer, N. Lutkenhaus, C. Monyk, P. Painchault, M. Peev, A. Poppe, T. Pornin, J. Rarity, R. Renner, G. Ribordy, M. Riguidel, L. Salvail, A. Shields, H. Weinfurter, and A. Zeilinger,
    Using quantum key distribution for cryptographic purposes : a survey,
    arXiv:quant-ph/0701168 (2007) ; Theoretical Computer Science 560, 62 (2014).


  51. B. Kraus, C. Branciard, and R. Renner,
    Security of quantum-key-distribution protocols using two-way classical communication or weak coherent pulses,
    Physical Review A 75, 012316 (2007).


  52. C. Branciard, N. Gisin, N. Lütkenhaus, and V. Scarani,
    Zero-error attacks and detection statistics in the Coherent One-Way protocol for quantum cryptography,
    Quantum Information & Computation 7, 639 (2007).


  53. C. Branciard, N. Gisin, B. Kraus, and V. Scarani,
    Security of two quantum cryptography protocols using the same four qubit states,
    Physical Review A 72, 032301 (2005).


  54. B. C. Daly, N. C. R. Holme, T. Buma, C. Branciard, T. B. Norris, D. M. Tennant, J. A. Taylor, J. E. Bower, S. Pau,
    Imaging nanostructures with coherent phonon pulses,
    Applied Physics Letters 84, 5180 (2004).


Participation to conferences, workshops, summer schools :


Invited presentations :

- [Upcoming :] Relativistic Quantum Information - North (RQI-N 2019) International Conference and School, Tainan (Taiwan), May 27 - June 1, 2019. Invited to give 3 hours of lectures on Quantum nonlocality, Bell’s inequalities, and quantum causality.

- Quantum Maiwar workshop, Brisbane (Australia), November 6-9, 2018. Invited talk : Communication through coherent control of quantum channels.

- Modern Topics in Quantum Information −− Quantum Foundations and Quantum Information Workshop, Natal (Brasil), July 30 - August 3, 2018. Invited talk : Quantum processes and correlations with no definite causal order.

- International Symposium on New Frontiers in Quantum Correlations (ISNFQC18), Kolkata (India), January 29 - February 2, 2018. Invited talk : Quantum processes and correlations with no definite causal order.

- Nanyang Quantum 2017 Workshop, Singapore, December 11-13, 2017. Invited talk : Quantum Superpositions of Causal Orders.

- International Conference on Quantum Foundations, Patna (India), December 4-9, 2017. Invited talk : Multipartite quantum processes and correlations with no definite causal order.

- “Quantum Causal Structures” Kick-Off Meeting Vienna (Austria), April 10-11, 2017. Invited talk : Causality in multipartite quantum processes.

- Quantum and Beyond (QB), Växjö (Sweden), June 13-16, 2016. Invited talk : Quantum processes with no definite causal order.

- Workshop on Quantum Networks, Barcelona (Spain), March 30 - April 1, 2016. Invited talk : Quantum processes with no definite causal order.

- International School and Conference on Quantum Information (ISCQI) 2016, Bhubaneswar (India), February 9-18, 2016. Invited talk : Quantum processes with no definite causal order.

- Workshop on Quantum Nonlocality, Causal Structures and Device-Independent Quantum Information, Tainan (Taiwan), December 10-14, 2015. Invited talk : (Quantum ?) Processes and Correlations with no definite causal order.

- International Conference on Quantum Foundations 2015, Patna (India), November 30 - December 4, 2015. Invited talk : (Quantum ?) Processes and Correlations with no definite causal order.

- Conference on Causality in a Quantum World, Twin Waters (Australia), August 16-21, 2015. Invited talk : (Quantum ?) Processes and Correlations with no definite causal order.

- Workshop on Physics and Information, Paris (France), June 29-30 and July 1st, 2015. Invited talk : Does a quantum state represent reality, or just our knowledge of it ?

- Discussion day on the "Foundations of Quantum Theory", Paris (France), December 8, 2014. Invited talk : Quantum indistinguishability is not due to some lack of knowledge of some underlying reality.

- Advances in Quantum Information and Quantum Simulation, Lyon (France), November 17-19, 2014. Invited talk : Causal relations in a quantum world.

- Gisin’14 Workshop, Riederalp (Switzerland), September 8-12, 2014. Invited talk : How ψ-epistemic models fail at explaining quantum indistinguishability.

- Quantum Science Symposium ASIA-2013, Tokyo (Japan), November 25-26, 2013. Invited talk : How well can one jointly measure two incompatible observables on a given quantum state ?

- Meeting on Quantum Correlation and its application in Communication and Cryptography, Kolkata (India), September 2-3, 2013. Invited talk : Quantum steering and 1-sided Device-Independent Quantum Key Distribution.

- Gisin’60 Workshop, Les Bains du Val d’Illiez (Switzerland), May 29-June 1, 2012. Invited talk : General Incertitude Statement for Incompatible measurements with Noise.

- Rank Prize Funds Symposium on Optical Implementation of Quantum Information, Grasmere (United Kingdom), October 3-6, 2011. Invited talk : Optical tests of quantum foundations.

- Perimeter Institute - Australia Foundations (PIAF) workshop, Brisbane (Australia), December 1-3, 2010. Invited talk : Quantum non-locality : how much does it cost to simulate quantum correlations ?

- Highlights in Microtechnology Summer Course, Neuchâtel (Switzerland), June 22-July 4, 2009. Invited lecture : Quantum optics based crypting technologies.


(In addition to the presentations above, I have been invited to present my work at several renowned institutions worldwide, active in the fields of quantum information and quantum foundations, for group meetings or physics colloquia.)


Workshop organisation :

- 2014 Sydney Meeting on Quantum Foundations, Sydney (Australia), April 2-5, 2014. Co-organiser.


Other participations :

- European Quantum Technology Conference (EQTC19) : the First international conference of the European Quantum Flagship, Grenoble (France), February 18-22, 2019. Talk : Quantum circuits with quantum control of causal orders.

- Quantum Correlations Week, Singapore, February 19-23, 2018. Invited participation.

- Quantum Networks 2017, Oxford (UK), August 1-4, 2017. Attendance.

- Conference on Agency and (quantum) physics (AQP2016), Konstanz (Germany), September 20-23, 2016. Attendance.

- GDR IQFA - 6th Colloquium, Palaiseau (France), November 18-20, 2015. Attendance.

- The Time Machine Factory conference, Turin (Italy), October 25-28, 2015. Talk : (Quantum ?) Processes and Correlations with no definite causal order.

- hbar-kb Workshop on Thermodynamics of out-of-equilibrium quantum systems, Grenoble (France), September 29-October 1, 2014. Attendance.

- 7th Relativistic Quantum Information Workshop, Brisbane (Australia), December 9-10, 2013. Attendance.

- 13th Asian Conference on Quantum Information Science (AQIS’13), Chennai (India), August 25-30, 2013. Talk : How well can one jointly measure two incompatible observables on a given quantum state ?

- 20th Australian Institute of Physics Congress, Sydney (Australia), December 9-13, 2012. Talk : How well can one jointly measure two incompatible observables on a given quantum state ?

- 6th Relativistic Quantum Information Workshop, Brisbane (Australia), November 28-30, 2012. Attendance.

- Inaugural Workshop on Quantum-Photonic Hardware, Rottnest Island (Australia), October 22-25, 2012. Talk : Does one need to align and calibrate quantum devices ?

- 5th Relativistic Quantum Information Workshop, Brisbane (Australia), November 28-29, 2011. Attendance.

- NII Shonan Meeting on Hybrid Quantum Devices, Shonan Village (Japan), November 5-9, 2011. Attendance.

- 1st Annual Conference on Quantum Cryptography (QCRYPT 2011), Zurich (Switzerland), September 12-16, 2011. Poster : One-sided Device Independent Quantum Key Distribution : Security and feasibility.

- Benasque meeting on Quantum Information, Benasque (Spain), June 12-July 1, 2011. Attendance.

- Conceptual Foundations and Foils for Quantum Information Processing, Waterloo (Canada), May 9-13, 2011. Poster : Simulation of multipartite quantum correlations with classical communication.

- 19th Australian Institute of Physics Congress, Melbourne (Australia), December 5-9, 2010. Poster : Characterizing the Nonlocal Correlations Created in Entanglement Swapping Experiments.

- 4th Relativistic Quantum Information Workshop, Brisbane (Australia), November 22-24, 2010. Attendance.

- International Conference on Quantum Information Science, Stockholm (Sweden), October 4-8, 2010. Talk : Characterizing the nonlocal correlations created in entanglement swapping experiments.

- 10th Asian Conference on Quantum Information Science (AQIS’10), Tokyo (Japan), August 27-31, 2010. Talk : Characterizing the nonlocal correlations created in entanglement swapping experiments.

- 22nd International Conference on Atomic Physics (ICAP 2010), Cairns (Australia), July 25-30, 2010. Attendance.

- 10th International Conference on Quantum Communication, Measurement and Computation (QCMC 2010), Brisbane (Australia), July 19-23, 2010. Attendance.

- Quantum Measurement and Control Workshop, Sydney (Australia), February 11-13, 2010. Attendance.

- Workshop on Quantum Cryptography with Finite Resources, Singapore, December 4-6, 2008. Attendance.

- Secoqc QKD Network Demonstration and Scientific Conference, Vienna (Austria), October 8-10, 2008. Attendance.

- 8th Asian Conference on Quantum Information Science (AQIS’08), Seoul (South-Korea), August 25-31, 2008. Talk : Leggett’s model and beyond : testing quantum correlations versus single-particle properties.

- Workshop on Information Primitives and Laws of Nature, Zurich (Switzerland), May 13-17, 2008. Attendance.

- International Conference on Quantum Information Processing and Communication (QIPC 2007), Barcelona (Spain), October 15-19, 2007. Poster : Distributed phase reference QKD protocols : new upper bounds for security.

- Asia Pacific Workshop and Conference in Quantum Information Science (APWCQIS 07), Singapore, July 30-August 2, 2007. Talk : Distributed phase reference schemes for QKD : security considerations and new upper bounds.

- Theory and Realisation of Practical Quantum Key Distribution (Tropical QKD) , Waterloo (Canada), June 11-14, 2007. Attendance.

- 4th Canadian Quantum Information Students’ Conference, Waterloo (Canada), June 1-5, 2007. Talk : Distributed phase reference schemes for QKD : explicit attacks and security considerations.

- 7th Canadian Summer School on Quantum Information, Waterloo (Canada), May 27-31, 2007. Attendance.

- The 9th Workshop on Quantum Information Processing (QIP 2006), Paris (France), January 16-20, 2006. Poster : Security of two QKD protocols using the same four qubit states.


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