Simone Severini

Department of Computer Science and
Department of Physics & Astronomy
University College London
Gower Street
WC1E 6BT London
United Kingdom


I am a Royal Society University Research Fellow and a Reader in Physics of Information.

I obtained my PhD from Bristol University, in the then newly created Quantum Computation and Information Group. My advisor was Richard Jozsa, whose advisor was Roger Penrose. I was a visiting student at UC Berkeley (and MSRI), and previously I studied Chemistry at the University of Siena and Philosophy (Logic) at the University of Florence. I was a Newton International Fellow at UCL, a Post-Doctoral Research Fellow of the Institute for Quantum Computing and the Department of Combinatorics & Optimization at the University of Waterloo, mentored by Michele Mosca, and a Post-Doctoral Research Assistant in the Department of Computer Science and the Department of Mathematics at the University of York. My long term scientific visits include CRI, CWI, MIT, Nankai, NUS and RISC-Linz.

My links at UCL are Intelligent Systems Group, UCL Quantum, CoMPLEX Research Group, UCL Institute of Origins, and London Center for Nanotechnology.

I am currently interested on:


My research papers can be found in arXiv, MathSciNet, MPRA, PubMed, and IRIS.


Professional service


Quantum information and graphs: In 2008, at the Perimeter Institute for Theoretical Physics, we organized a conference titled Quantum Information and Graph Theory: emerging connections. Below is an incomplete list of references on this topic (Oct 2011):

Graph states: R. Raussendorf, D.E. Browne, H.J. Briegel, Measurement-based quantum computation with cluster states, Phys. Rev. A 68, 022312 (2003). arXiv:quant-ph/0301052v2; M. Hein, W. Dür, J. Eisert, R. Raussendorf, M. Van den Nest, H.-J. Briegel, Entanglement in Graph States and its Applications, Proceedings of the International School of Physics "Enrico Fermi" on "Quantum Computers, Algorithms and Chaos", Varenna, Italy, July, 2005. arXiv:quant-ph/0602096v1
State transfer on spin systems: M. Christandl, N. Datta, T. C. Dorlas, A. Ekert, A. Kay, A. J. Landahl, Perfect Transfer of Arbitrary States in Quantum Spin Networks, Phys. Rev. A 71, 032312 (2005). arXiv:quant-ph/0411020v2; C. Godsil, State Transfer on Graphs, 2011. arXiv:1102.4898v2 [math.CO]
Quantum expanders: A. Ben-Aroya, A. Ta-Shma, Quantum expanders and the quantum entropy difference problem, 2007. arXiv:quant-ph/0702129v3; A. W. Harrow, R. A. Low, Efficient Quantum Tensor Product Expanders and k-designs, Proceedings of RANDOM 2009, LNCS, 5687:548-561, 2009. arXiv:0811.2597v3 [quant-ph]
Quantum walks: D. Aharonov, A. Ambainis, J. Kempe, U. Vazirani, Quantum walks on graphs, Proceedings of ACM Symposium on Theory of Computation (STOC'01), July 2001, p. 50-59; A. Ambainis, Quantum walks and their algorithmic applications, International Journal of Quantum Information, 1:507-518, 2003. arXiv:quant-ph/0403120v3; M. Mohseni, P. Rebentrost, S. Lloyd, A. Aspuru-Guzik. Environment-assisted quantum walks in photosynthetic energy transfer, Journal of Chemical Physics 129, 174106 (2008). arXiv:0805.2741v2 [quant-ph]; A. M. Childs, Universal computation by quantum walk, Phys. Rev. Lett. 102, 180501 (2009). arXiv:0806.1972v1 [quant-ph]
Quantum graphs: T. Kottos and U. Smilansky, Quantum Chaos on Graphs, Phys. Rev. Lett. 79, 4794-797, (1997); U. Smilansky, Quantum chaos on discrete graphs, 2007. arXiv:0704.3525v1 [math-ph]
Graphs of unitary matrices: L. Deaett, The minimum semidefinite rank of a triangle-free graph, Linear Algebra and its Applications 434 (2011), 1945-1955; T. J. Osborne, Approximate Locality for Quantum Systems on Graphs, Phys. Rev. Lett. 101, 140503 (2008). arXiv:quant-ph/0611231v2
Complexity metrics: R. Jozsa, On the simulation of quantum circuits, 2006. arXiv:quant-ph/0603163v1; I. L. Markov, Y. Shi, Simulating quantum computation by contracting tensor networks, SIAM Journal on Computing, 38(3):963-981, 2008. arXiv:quant-ph/0511069v7; D. Aharonov, Z. Landau, J. Makowsky, The quantum FFT can be classically simulated, 2006, arXiv:quant-ph/0611156v2
Isomorphism (via encoding): K. Audenaert, C. D. Godsil, G. F. Royle, T. Rudolph, Symmetric squares of graphs, J. Comb. Theory, Ser. B 97(1): 74-90 (2007). arXiv:math/0507251v1 [math.CO]; J. K. Gamble, M. Friesen, D. Zhou, R. Joynt, S. N. Coppersmith, Two-particle quantum walks applied to the graph isomorphism problem. Phys. Rev. A, 81(5):052313, 2010. arXiv:1002.3003v1 [quant-ph]
Network coding: M. Hayashi, K. Iwama, H. Nishimura, R. Raymond, and S. Yamashita. Quantum network coding. In STACS 2007, volume 4393 of Lecture Notes in Computer Science, pages 610–621, 2007. arXiv:quant-ph/0601088v2; D. Leung, J. Oppenheim, and A.Winter. Quantum network communication — the butterfly and beyond. IEEE Transactions on Information Theory, 56(7):3478–3490, 2010. arXiv:quant-ph/0608223v5
Complex networks: S. Perseguers, M. Lewenstein, A. Acín, J. I. Cirac, Quantum complex networks, Nature Physics 6, 539 - 543 (2010). arXiv:0907.3283v1 [quant-ph]
Graphs as channels; T. S. Cubitt, D. Leung, W. Matthews, A. Winter, Improving zero-error classical communication with entanglement, Phys. Rev. Lett., 104(23):230503, 2010. arXiv:0911.5300v2 [quant-ph]; D. Leung, L. Mancinska, W. Matthews, M. Ozols, A. Roy, Entanglement can increase asymptotic rates of zero-error classical communication over classical channels, 2010. arXiv:1009.1195v2 [quant-ph]
Quantum colouring: C. Godsil, M. W. Newman, Coloring an Orthogonality Graph, SIAM J. Discrete Math. 22(2): 683-692 (2008). arXiv:math/0509151v1 [math.CO]; J. Fukawa, Hi. Imai, F. Le Gall, Quantum Coloring Games via Symmetric SAT Games. Presented as a long talk at the 11th Asian Quantum Information Science Conference (AQIS 2011).
Background independent models of quantum gravity based on time-dependent graphs: A. Hamma, F. Markopoulou, Background independent condensed matter models for quantum gravity, New J. Phys. 13:095006, 2011. arXiv:1011.5754v1 [gr-qc]; F. Caravelli, F. Markopoulou, Properties of quantum graphity at low temperature, Phys. Rev. D 84 024002, 2011. arXiv:1008.1340v3 [gr-qc]

And here a list of references that I find useful:



Chris Banerji, MRes and PhD, UCL. Octavio Zapata, PhD, UCL. Nadish de Silva, visiting student, University of Oxford. Daniel Temko, PhD, UCL. Arthur Guerard, MRes, UCL. Sherman Ip, MRes, UCL. Yu-Ching Yang, Mres, UCL. Andrea Casaccino, PhD, University of Siena / MIT (then at General Electrics). Alessandro Cosentino, Laurea Magistrale, University of Pisa (then PhD at University of Waterloo with John Watrous). James West, PhD, UCL (then at a hedge fund). Janos Hodsagi, MRes, UCL. Lourdes Sriraja, MRes, UCL. Tommaso Gagliardoni, Laura Magistrale, University of Perugia (then at the Center for Advanced Security Research Darmstadt). Soomin Kim and Emma Rahman (Nuffield Research Placement Scheme). [CPs CoMPLEX: Thomas Wyatt, Sophie Atkinson , Janos Hodsagi, Andrew Maher, Tim Lucas, Robert Bentham, Teresa Attenborough], Si Bing MSci, University of Bristol. Walter Vinci, postdoc, UCL (then postdoc at University of Southern California).

Research students applications: Computer Science: here (PRISM); Centre for Doctoral Training in Delivering Quantum Technologies: here; Centre for Mathematics, Physics and Engineering in the Life Sciences and Experimental Biology (CoMPLEX): here.

Module PHASGQ03 Quantum Communication and Computation for Quantum Technologies (Strand 2: Quantum Computation and Algorithms), 2015

Strand 1: Quantum Cryptography (Fernando Brandao and Lluis Masanes); Strand 3: Quantum Error Correction and Fault Tolerance (Dan Browne); Strand 4: Lab: Quantum Key Distribution (Jeroen Elzerman). Notes: Strand 1, Quantum Information Theory, from “PHASGQ01 Physics and Foundations of Quantum Technologies” thought by Jonathan Oppenheim is useful.