Simone Severini

Department of Computer Science
University College London
Gower Street
WC1E 6BT London
United Kingdom

Office: GS3.13
Tel: +44 (0)20 3108 7093 (Direct Dial)
Internal: 57093
Fax: +44 (0)20 7387 1397


I am a Royal Society University Research Fellow and a Reader in Physics of Information with the Department of Computer Science at UCL. At present, I am also a Visiting Chair Professor with the Institute of Natural Sciences at Shanghai Jiao Tong University (my page at SJTU is here), as a recipient of a 1000 Talents Program grant. I started at UCL the Computer Science Quantum Information Interest Group, which is now part of the Intelligent Systems Group within the Department of Computer Science. Our activities are linked with the UCL Institute for Quantum Science and Technology. I was a Newton International Fellow with the Department of Physics & Astronomy at UCL. I was 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. 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, where I got my laurea (pre-Bologna). My long term scientific visits include CRI, CWI, MIT, Nankai, NUS and RISC-Linz. I have been a Visiting Fellow of the Isaac Newton Institute for Mathematical Sciences, Cambridge, during three thematic programmes. I am a member of the steering committee of the Conference on the Theory of Quantum Computation, Communication and Cryptography (TQC) and a member of the Computer Science Evaluation Group at the Natural Sciences and Engineering Research Council of Canada (NSERC) (see below for a list of professional services). I serve in the editorial board of Philosophical Transactions of the Royal Society A. I am a recipient of the 2015 Talented Young Italians Awards: Research & Innovation given by the Italian Chamber of Commerce and Industry for the UK. My other links at UCL are CoMPLEX Research Group, UCL Institute of Origins, and London Center for Nanotechnology. My research papers can be found in arXiv, MathSciNet, MPRA, PubMed, and IRIS. Here is a web page for the Quantum Computing, Information, and Algebras of Operators (QCIAO) collaboration.



Professional service

Quantum information and graphs (Oct2011)

Useful references


Current: Octavio Zapata (PhD), Nadish de Silva (postdoc), Daniel Temko (PhD; Awarded a Bogue Fellowship at Franziska Michor's Laboratory, Harvard University.), Josh Lockhart (PhD), David Roberson (postdoc), James Townsend (PhD, joint with Mark Herbster), Marcello Benedetti (PhD, UCL/NASA).

Past: Fabiano Andrade (scientific visitor, The State University of Ponta Grossa, Brazil, 2014-15), Nadish de Silva, PhD, visiting student, University of Oxford at UCL, Josh Lockhart, MRes, UCL, Adrea 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), Chris Banerji, MRes and PhD, Awarded the UCL Faculty of Mathematical and Physical Sciences Postgraduate Prize for outstanding achievements during the MRes year at CoMPLEX; Recipient of the INBIOMEDvision Training Challenge Prize 2012. Hairu Xu: Visiting Student from Guangdong University of Technology, February 2014-April 2014, Banghai Wang: Academic Visitor from Guangdong University of Technology, April 2013-March 2014, Zhihao Ma: Academic Visitor from Shanghai Jiao Tong University, October 2011-October 2012. Abdul Bhutto, Nuffield Research Placement Scheme, Summer 2015, Zahra Najib, Nuffield Research Placement Scheme, Summer 2015, Tianyu Ye, postdoc. Arthur Guerard, MRes, Yu-Ching Yang, MRes (together with Marco Grimaldi, HarperCollins).

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: reviewing Strand 1, Quantum Information Theory, from “PHASGQ01 Physics and Foundations of Quantum Technologies” thought by Jonathan Oppenheim is useful.

PHASGQ03 2016: Syllabus

See general references of 2015. Mostly similar to the 2015 lectures. Ashley Montanaro as a guest lecturer.

Recap and warm-up: Historical background, Ket/bra notation, quantum registers, projective measurements in different bases, composite systems, unitary evolution, classical limit and doubly stochastic matrices vs. unitary matrices, qubits, superpositions, basic quantum gates (Hadamard, bit flip, phase flip, phase gate, CNOT), No-cloning theorem, diagrams and circuits, partial measurements, Hamiltonian dynamics. Exercises (C_swap). From classical to quantum computation: Entanglement (measuring entanglement), classical gates, Boolean functions, Boolean circuits. A bit about thermodynamics of computation: Landauer's principle, CCNOT, universal sets, Solovay-Kitaev's theorem, function evaluation in a quantum computer, parallelism, the notion of query complexity, Deutsch's algorithm, Deutsch-Jozsa's algorithm, Exercise: measuring interference. (Interference as an ingredient for quantum speed-up: the power of negative numbers in probability densities.) The Fourier transform and its applications: Simon's algorithm, Fourier transform (classical, quantum), FFT algorithm, efficiency, quantum phase estimation, Hidden Subgroup Problem (HSP). Exercise: Fourier transform. Shor's factoring algorithm: factoring, reduction to period finding, Shor's method for period finding, continued fractions and post-processing, Group-theoretic setting for the Fourier transform (representations, abelian vs. nonabelian case). Graph isomorphism as an HSP. Grover's search: Unstructured database search, Grover's algorithm, Grover's iterate, Geometric argument, Search via continuous walks. Optimality. Walks: Graphs 101: see Diestel's book. Matrices representing graphs, Spectrum. Random walks, Mixing time and the eigenvalue gap and limiting distributions, Quantum approaches and physical intuition, Coined quantum walks, Grover walks (meaning, with Grover coin), Average and instantaneous mixing (cycle and hypercube), Continuous walks, State transfer on spin systems (perfect state transfer, pretty good state transfer). Other models of quantum computation: Graph states (two definitions), the cluster state, measurement based quantum computation, entanglement as a resource, the adiabatic theorem, adiabatic quantum computation, eigenvalue gap (again, but in a different context), universality, examples of algorithms (Grover search), issues concerning adiabatic quantum computation. See this great talk by Andrew Childs. Quantum complexity theory [Guest lecturer: Ashley Montanaro]: P, NP, P-complete, PSPACE, NP-completeness, Notion of polynomial reductions, P vs NP question, BPP, BQP, QMA, inclusion diagrams (classical and quantum classes). Reference: J. Watrous, Quantum Computational Complexity, arXiv:0804.3401 [quant-ph]. Hamiltonian complexity [Guest lecturer: Toby Cubitt]: Quantum computation aims to engineer complex many-body systems to process information in ways that would not be possible classically. Many-body physics aims to understand the complex behaviour of naturally-occurring many-body systems. In a sense, they are two sides of the same coin. We will investigate the computational complexity of quantum many-body systems, culminating in Kitaev's seminal proof of QMA-hardness of the ground state problem for local Hamiltonians.