# Giulio Chiribella

The University of Hong Kong (HKU)

Areas of research:

### Overview

I obtained my PhD at Pavia University under the supervision of Professor Giacomo Mauro D'Ariano. From 2006 to 2009 I have been a postdoctoral fellow of the Quantum Information Group at Pavia University.

### Research Interests

The core of my research activity lies at the intersection between Quantum Foundations and Quantum Information. The theory of Quantum Information Processing showed a wealth of protocols and algorithms stemming from the counterintuitive mathematics of quantum mechanics. Also, it emphasized that the rules of information processing are dictated by physics and that different physical theories, like classical and quantum mechanics, entail very different models of information processing. One of the main challenges now is to completely characterize the quantum model of information processing through a small set of physical axioms, thus reducing the variety of known quantum protocols to few basic unifying principles. One motivation to do so is, in my opinion, that the present understanding of the interplay between physics and information processing is too indirect, and the fundamental connections between physical principles and quantum protocols are not as transparent as they could be. The main reason for that is that the connections between different protocols and quantum mechanical features are not direct, but instead they are mediated by the abstract formalism of Hilbert spaces and operator algebras.
I believe that eventually the understanding of quantum theory achieved through the axiomatization of quantum information processing will be extremely useful for the advancement of fundamental physics. However, providing a conceptual foundation of quantum information processing will not be the conclusion of the foundational research about the interplay between physical principles and models of information processing. An ambitious goal would be to provide a classification of all possible physical models of information processing, in analogy to the classification of all possible models of geometry that was achieved in the nineteenth century with the advent of non-euclidean geometries.

### Positions Held

- 2006-2009, Dipartimento di Fisica &quot;A. Volta&quot;, University of Pavia (Italy), Postdoctoral Fellow
- August 2007, Visiting Scholar at University of Sydney (Australia)

### Awards

### Recent Publications

- D. Genkina, G. Chiribella, and L. Hardy, Optimal Probabilistic Simulation of Quantum Channels from the Future to the Past, Phys. Rev. A 85, 022330 (2012)
- G. Chiribella, G. M. D'Ariano, and P. Perinotti, Informational derivation of Quantum Theory, Phys. Rev. A 84, 012311 (2011), arXiv: 1011.6451
- G. Chiribella, On quantum estimation, quantum cloning and finite quantum de Finetti theorems, Theory of Quantum Computation, Communication, and Cryptography, revised selected papers, Lecture Notes in Computer Science 6519/2011, 9 (2011), arXiv: 1010.1875
- G. Chiribella, M. Dall'Arno, G. M. D'Ariano, C. Macchiavello, and P. Perinotti, Quantum error correction with degenerate codes for correlated noise, Phys. Rev. A 83, 052305 (2011), arXiv: 1007.3655
- A. Bisio, G. Chiribella, G. M. D'Ariano, P. Perinotti, Minimal computational-space implementation of multi-round quantum protocols, Phys. Rev. A 83, 022325 (2011), arXiv: 1006.1780
- A. Bisio, G. Chiribella, G. M. D'Ariano, and P. Perinotti Information - Disturbance Tradeoff in the Estimation of a Unitary Transformation, Phys. Rev. A 82, 062305 (2010), arXiv: 1006.5665
- G. Chiribella, G. M. D'Ariano, and P. Perinotti, Probabilistic Theories with Purification, Phys. Rev. A. 81, 062348 (2010), arXiv: 0908.1583.
- G. Chiribella, G. M. D'Ariano, and P. Perinotti, Theoretical framework for quantum networks, Phys. Rev. A 80, 022339 (2009), arXiv: 0904.4483
- A. Bisio, G. Chiribella, G. M. D'Ariano, S. Facchini, and P. Perinotti, Optimal quantum learning of a unitary transformation, Phys. Rev. A 81, 032324 (2010), arXiv: 0903.0543
- G. Chiribella, G. M. D'Ariano, and P. Perinotti, Realization schemes for quantum instruments in finite dimensions, J. Math. Phys. 50, 042101 (2009), arXiv: 0810.3211
- G. Chiribella, G. M. D'Ariano, and D. M. Schlingemann, Barycentric decomposition of quantum measurements in finite dimensions, J. Math. Phys. 51, 022111 (2010), arXiv: 0807.4803
- A. Bisio, G. Chiribella, G. M. D'Ariano, S. Facchini, and P. Perinotti, Optimal quantum tomography for states, measurements, and transformations, Phys. Rev. Lett. 102 (2009) 010404, arXiv: 0806.1172
- G. Chiribella, G. M. D'Ariano, and P. Perinotti, Optimal cloning of unitary transformations, Phys. Rev. Lett. 101, 180504 (2008), arXiv: 0804.0129
- G. Chiribella, G. M. D'Ariano, and P. Perinotti, Transforming quantum operations: quantum supermaps, EPL 83, 30004 (2008), arXiv: 0804.0180
- G. Chiribella, G. M. D'Ariano, and Paolo Perinotti, Memory effects in quantum channel discrimination, Phys. Rev. Lett. 101, 180501 (2008), arXiv: 0803.3237
- G. Chiribella, G. M. D'Ariano, and P. Perinotti, Quantum Circuits Architecture, Phys. Rev. Lett. 101, 060401 (2008), arXiv: 0712.1325
- G. Adesso and G. Chiribella, Quantum Benchmark for Teleportation and Storage of Squeezed States, Phys. Rev. Lett. 100, 170503 (2008), arXiv: 0711.3608
- G. Chiribella, G.M. D'Ariano, and D. M. Schlingemann, How continuous quantum measurements in finite dimension are actually discrete, Phys. Rev. Lett. 98, 190403 (2007), arXiv: quant-ph/0702068
- F. Buscemi, G. Chiribella, G. M. D'Ariano, Quantum erasure of decoherence, Open Sys. & Information Dyn. 14, 53 (2007), arXiv: quant-ph/0611070
- G. Chiribella, G. M. D'Ariano, and M. F. Sacchi, Joint estimation of real squeezing and displacement, J. Phys. A 39, 2127 (2006), arXiv: quant-ph/0511203
- G. Chiribella, G. M. D'Ariano, P. Perinotti, Applications of the group SU(1,1) for quantum computation and tomography, Laser Physics 16,1572 (2006), arXiv: quant-ph/0610142
- G. Chiribella and G. M. D'Ariano, Quantum information becomes classical when distributed to many users, Phys. Rev. Lett. 97, 250503 (2006), arXiv: quant-ph/0608007
- G. Chiribella, G. M. D'Ariano, C. Macchiavello, P. Perinotti, and F. Buscemi, Superbroadcasting and classical information Phys. Rev. A 75, 012315 (2007), arXiv: quant-ph/0608153
- G. Chiribella, L. Maccone, and P. Perinotti, Secret quantum communication of a reference frame, Phys. Phys, Rev. Lett. 98, 120501 (2007), arXiv: quant-ph/0608042
- G. Chiribella, G. M. D'Ariano, P. Perinotti, and M. F. Sacchi, Maximum likelihood estimation for a group of physical transformations, Int. J. Quantum Inf. 4, 453 (2006), arXiv: quant-ph/0507007
- G. Chiribella, G. M. D'Ariano, Extremal covariant measurements, J. Math. Phys. 47, 092107 (2006), arXiv: quant-ph/0603168
- G. Chiribella, G. M. D'Ariano, AND M. F. Sacchi, Optimal estimation of squeezing, Phys. Rev. A 73, 062103 (2006), arXiv: quant-ph/0601103
- G. Chiribella, G. M. D'Ariano, P. Perinotti, and N. J. Cerf, Extremal quantum cloning machines, Phys. Rev. A 72 042336 (2005), arXiv: quant-ph/0507130
- G. Chiribella, G. M. D'Ariano, and M. F. Sacchi, Optimal estimation of group transformations using entanglement, Phys. Rev. A 72 042338 (2005), arXiv: quant-ph/0506267
- F. Buscemi, G. Chiribella, and G. M. D'Ariano, Inverting quantum decoherence by classical feedback from the environment, Phys. Rev. Lett. 95, 090501 (2005), arXiv: quant-ph/0504195
- G. Chiribella and G. M. D'Ariano, Extremal covariant POVM's, J. Math. Phys. 45, 4435 (2004), arXiv: quant-ph/0406237
- G. Chiribella, G. M. D'Ariano, P. Perinotti, and M. F. Sacchi, Efficient use of quantum resources for the transmission of a reference frame, Phys. Rev. Lett 93, 180503 (2004), arXiv: quant-ph/0405095
- G. Chiribella, G. M. D'Ariano, P. Perinotti, and M. F. Sacchi, Covariant quantum measurements which maximize the likelihood, Phys. Rev. A 70, 062105 (2004), arXiv: quant-ph/0403083
- G. Chiribella, Perfect discrimination of no-signalling channels via quantum superposition of causal structures, arXiv: 1109.5154
- G. Chiribella, A. Toigo, and V. Umanita'Ã
- G. Chiribella, G. M. D'Ariano, P. Perinotti, and B. Valiron, Beyond Quantum Computers, arXiv: 0912.0195
- G. Chiribella, V. Giovannetti, L. Maccone, P. Perinotti, Teleportation can only transfer speakable quantum information, arXiv: 1008.0967
- G. Chiribella, Group theoretic structures in the estimation of an unknown unitary transformation, J. Phys.: Conf. Ser. 284, 012001 (2011), arXiv: 1012.2130
- G. Chiribella, G. M. D'Ariano, and P. Perinotti, Optimal covariant quantum networks,Proc. QCMC-08, p.47, AIP (2009).

### Seminars

- Quantum Theory from Quantum Information, Theory Canada 7, Meeting of the Division of Theoretical Physics of the Canadian Association of Physicists, 7-9 June 2012, Lethbridge (Canada)
- Parallelization and Factorization Theorems in Quantum Metrology, Pecs Workshop on Quantum Information and Quantum Optics, 28-30 May 2012, Pecs (Hungary)
- Parallelization and Factorization Theorems in Quantum Metrology, the sixth Conference on the Theory of Quantum Computation, Communication and Cryptography, May 17-19 2012, Tokyo (Japan)
- Quantum Theory: the Pure and Reversible Theory of Information, Tsinghua-Aarhus Workshop on Quantum Information Science, 21-25 May, Tsinghua University, Beijing (China)
- Introduction to the framework of operational-probabilistic theories, Bellairs Workshop on Quantum Foundations, Barbados, March 31-April 7 2012
- Quantum controlled paths for perfect discrimination of no-signalling channels, The March Meeting of the American Physical Society, February 27-March 2 2012, Boston (US)
- Quantum superposition of causal structures and probabilistic simulation of quantum channels backward in time, the third Nagoya Winter Workshop on Quantum Information, Meausurement, and Foundations, 14-18 February 2012, Nagoya University (Japan)
- Quantum Theory, with less causality, Quantum Foundations in the Light of Quantum Information III, December 6-9 2011, Montreal, Canada
- Quantum Theory, namely where information and physics meet, Universite' de Montreal (CA), May 4 2011
- A complete set of informational principles for quantum theory, Colloquium at Institute for Quantum Computation (Waterloo, CA), March 7 2011
- Toward a Conceptual Foundation of Quantum Information Processing, The 2011 March Meeting of the American Physical Society, Dallas (US), March 21-25
- General theories of information-processing: basic framework and introduction to the key principles, The Second Nagoya Winter Workshop on Quantum Information, Measurement, and Foundations, Nagoya (Japan), February 14-18 2011
- A portrait of quantum mechanics as a new theory of information processing, Universitat Autonoma Barcelona, January 13 2011
- Quantum theory from informational axioms, University College London (UK), January 24 2011
- An informational derivation of Quantum Theory, Center for Mathematical Sciences, University of Cambridge (UK), January 20 2011
- A portrait of quantum mechanics as a new theory of information processing, departmental seminar at Computing Laboratory, University of Oxford (UK), January 18 2011
- An informational derivation of Quantum Theory, Center for Mathematical Sciences, University of Cambridge (UK), January 20 2011
- A portrait of quantum mechanics as a new theory of information processing, departmental seminar at Computing Laboratory, University of Oxford (UK), January 18 2011
- A portrait of quantum mechanics as a new theory of information processing, Universitat Autonoma Barcelona, January 13 2011
- Quantum theory from informational axioms, University College London (UK), January 24 2011
- Quantum measurement theory: from quantum states to quantum networks, University of Saskatchewan (Saskatoon, CA), Department of Mathematics, November 3 2010
- Optimal Estimation of Quantum Signals in the Presence of Symmetry', University of Saskatchewan (Saskatoon), PIMS Applied Mathematics Seminar Series, November 2 2010
- Quantum measurement theory: from quantum states to quantum networks, University of Saskatchewan (Saskatoon, CA), Department of Mathematics, November 3 2010
- Optimal Estimation of Quantum Signals in the Presence of Symmetry', University of Saskatchewan (Saskatoon), PIMS Applied Mathematics Seminar Series, November 2 2010
- Optimal quantum learning of an unknown unitary transformation and multiround reference frame alignment, Institute for Quantum Information Science, University of Calgary, October 26 2010
- Optimal quantum learning of an unknown unitary transformation and multiround reference frame alignment, Institute for Quantum Information Science, University of Calgary, October 26 2010
- Group theoretic quantum estimation (plenary lecture), The XXVIII International Colloquium on Group-Theoretical Methods in Physics, Newcastle upon Tyne (UK), July 26-30 2010
- Purity and reversibility at the foundation Quantum Information Processing, 16th U.K. and European Meeting on the Foundations of Physics, Aberdeen (UK), July 5-7 2010
- Towards a conceptual foundation of Quantum Information Processing, Imperial College London (UK), June 15 2010
- Purity and reversibility as a paradigm for Quantum Information Processing, Workshop on Fundamentals of Physics and Information, ETH Zuerich (Switzerland), June 8-11 2010
- Probabilistic theories with purification, Computing Laboratory, University of Oxford (UK), April 20 2010
- Optimal pure state estimation as a randomized universal cloning, The fifth Conference on the Theory of Quantum Computation, Communication and Cryptography, Leeds (UK), April13-15 2010
- Probabilistic theories with purification, Center for Mathematical Sciences, University of Cambridge (UK), March 4 2010
- Probabilistic theories with purification, The Nagoya Winter Workshop on Quantum Information, Measurement, and Foundations, Nagoya, Japan, February 18-24 2010
- Optimal storing and retrieving of unitary transformations, International Conference on Quantum Information Processing and Communication, Roma (Italy), September 21-25
- Dilation of physical processes in general probabilistic theories, Cambridge Summer Workshop on Quantum information theory with correlated and finite resources, Cambridge (UK), July 6-8 2009
- Learning an unknown unitary transformation, University of Nagoya (Japan), March 9 2009
- Optimal quantum learning and multiround reference frame alignment, DEX-SMI Workshop on Quantum Statistical Inference 2009, National Institute for Informatics (Tokyo, Japan), March 2- 4 2009
- Optimal quantum networks with symmetry, GIQ Mini-Workshop 2009, February 4-6 2009, Universitat Autonoma de Barcelona (Spain)
- On quantum clocks and gyroscopes, Italian Quantum Information Conference 2008, October 24-29 2008, Camerino (Italy)
- Asymptotic cloning, state estimation, and the finite versions of quantum de Finetti Theorem, XL Jubilee Symposium on Mathematical Physics: Geometry and Quanta, Torun (Poland), June 25-28 2008
- Optimal cloning of a secret quantum algorithm, ERATO Project (Tokyo Office), February 18 2008
- Optimal cloning of quantum channels, GSIS & DEX-SMI Workshop on Quantum statistical inference and entanglement, Sendai (Japan), February 11-12 2008
- The quantum versions of de Finetti theorem as the bridge between quantum cloning and state estimation, Workshop on Mathematical Methods in Quantum Mechanics, Bressanone (Italy), February 26-March 3 2007
- Quantum information becomes classical when ditributed to many users, QAP Focus Meeting: Quantum state and process estimation, Budmerice (Slovakia), 2 September 7- October 1 2006
- How fast quantum cloning converges to quantum state estimation?, Quantum Probability, Information and Control Symposium, Nottingham (UK), July 15-22 2006
- Optimal use of entanglement in the estimation of an unknown group transformation, XXXVIII Symposium on Mathematical Physics: Entanglement and Geometry, Torun (PL), June 4-7 2006
- Covariant strategies for the optimal estimation of unitary transformations, Institut fuer angewandte Mathematik der Universitaet Bonn (Germany), May 4 2006
- Optimal Estimation of Group Transformations using Entanglement, International Summer School on Quantum Information, Max Planck Institut fuer Physik Komplexer Systemen, Dresden (Germany), August 29 - September 23 2005
- Optimal Estimation of Group Transformations using Entanglement, ERATO Project (Tokyo), 26 July 2005
- Extremal Covariant Maps and Optimal Cloning of two Mutually Unbiased Bases, Universite Libre de Bruxelles (Belgium), November 22 2004
- Absolute Alignment of Reference Frames using Quantum Systems, YEP Meeting 2004, Budmerice (Slovakia), November 30 - December 4 2004
- Extremal Covariant POVMs, Workshop: Quantum Statistics--Quantum Measurements, Estimation, and Related Topics, Newton Institute, Cambridge (UK), November 15-19 2004
- PIRSA:12030111, Quantum Switches and Impossible Time Travels, 2012-03-06, Quantum Foundations
- PIRSA:11100104, The Pure and Reversible Pictures of Quantum Mechanics, 2011-10-14, Conceptual Gems of Theoretical Physics
- PIRSA:11050030, Opening Welcome, 2011-05-09, Conceptual Foundations and Foils for Quantum Information Processing
- PIRSA:10020070, Purity and reversibility as a paradigm for Quantum Information Processing, 2010-02-02, Quantum Foundations
- PIRSA:08120039, Admissible transformations of quantum networks and their applications in quantum information processing, 2008-12-12, Young Researchers Conference 2008
- PIRSA:04070006, Maximum likelihood and efficient use of quantum resources in the alignment of reference frames, 13/07/2004, Workshop on Reference Frames and Superselection Rules in Quantum Information Theory