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- Alioscia Hamma

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Tsinghua University - Centre for Quantum Information

Areas of Research:

Email: hamma.alioscia@gmail.com

Phone: x8552

My research is mainly concerned with Quantum Many-Body theory, Quantum Information, and Theoretical Condensed Matter. I am interested in showing how peculiar characteristics of quantum theory explain the observable behavior of many-body quantum systems. In particular, I am interested in the relaxation processes and degrade of information in quantum systems interacting with an environment and the theory of topological orders. They are both subjects in which the peculiarities of quantum theory are evident. Quantum information indeed degrades in a fundamentally different way than classical information, and topological orders in matter are not a classical order of the matter, but a quantum order. I am working on how to characterize topological orders using the most genuine characteristic of quantum theory, the entanglement.

Recently, I have been working on the topic of emergent gravity. The goal is to consider space-time dynamics as the effective theory of a quantum many-body system with simple degrees of freedom like a quantum spin network.

My most recent work is focused on the typicality of entanglement in physical states. Physical states are a tiny fraction of the Hilbert space of a quantum many body system. They are states that can be reached from a completely factored state by means of evolution with a local Hamiltonian for a polynomial time in the system size. I proved that these states are nearly maximal entangled. This has profound implications for the foundations of statistical mechanics.

- 03/2010-present Distinguished Research Fellow at the Perimeter Institute
- 09/2008-02/2010 Postdoctoral Fellow at the Perimeter Institute for Theoretical Physics, Waterloo ON, Canada
- 03/2008-09/2008: Visiting Scientist at RLE, Quantum Information Group, Massachusetts Institute of Technology, Cambridge MA
- 01/2008-09/2008: Associate Postdoctoral Fellow at Perimeter Institute for Theoretical Physics, Waterloo ON, Canada
- 12/2005-12/2007: Postdoctoral fellow at University of Southern California, Los Angeles CA
- 02/2003-12/2005: Research Associate at the Quantum Information Group at ISI, Torino, Italy
- 2004: Visiting Student at Massachusetts Institute of Technology, Cambridge MA

- Assistent Professor at Tsinghua University, Beijing

- Sebastian Montes, Alioscia Hamma, Phase diagram and quench dynamics of the Cluster-XY spin chain, Phys. Rev. E 86, 021101 (2012), arXiv: 1112.4414
- Dalimil Mazac, and Alioscia Hamma Topological order, entanglement, and quantum memory at finite temperature Annals of Physics 327 (2012), pp. 2096-2111; arXiv: 1112.0947
- Luigi Amico, Davide Rossini, Alioscia Hamma, Vladimir E. Korepin Optimal correlations in many-body quantum systems Phys. Rev. Lett. 108, 240503; arXiv: 1112.3280
- Bruno Tomasello, Davide Rossini, Alioscia Hamma, Luigi Amico Quantum discord in a spin system with symmetry breaking Contribution to the Festschrift volume in honour of Vladimir Korepin; arXiv: 1112.0361
- Juho Happola, Gabor B. Halasz, Alioscia Hamma, Universality and robustness of revivals in the transverse field XY model Phys. Rev. A 85, 032114; arXiv: 1011.0380
- Alioscia Hamma, S. Santra, and P. Zanardi Quantum entanglement in random physical states Phys. Rev. Lett. 109, 040502 (2012); arXiv: 1109.4391
- Francesco Caravelli, Alioscia Hamma, Fotini Markopoulou, Arnau Riera Trapped surfaces and emergent curved space in the Bose-Hubbard model Phys. Rev. D 85, 044046; arXiv: 1108.2013
- Quantum phase transition between cluster and antiferromagnetic states,Wonmin Son, Luigi Amico, Rosario Fazio, Alioscia Hamma, Saverio Pascazio, Vlatko Vedral, Europhys. Lett. vol. 95, 50001 (2011), arXiv: 1103.0251
- Symmetry breaking and correlations in a quantum many body system, Bruno Tomasello, Davide Rossini, Alioscia Hamma, Luigi Amico, Europhys. Lett. vol. 96, 27002 (2011), arXiv: 1012.4270
- Background independent condensed matter models for quantum gravity, Alioscia Hamma, Fotini Markopoulou, focus issue of the New Journal of Physics on "Classical and Quantum Analogues for Gravitational Phenomena and Related Effects", R. Schuetzhold, U. Leonhardt and C. Maia, Eds, arXiv: 1011.5754
- Lieb-Robinson bounds for commutator-bounded operators, Isabeau Premont-Schwarz, Alioscia Hamma, Israel Klich, Fotini Markopoulou-Kalamara, Phys. Rev. A 81, 040102(Rapid Communications) (2010) ; arXiv: 0912.4544
- A quantum Bose-Hubbard model with evolving graph as toy model for emergent spacetime, Alioscia Hamma, Fotini Markopoulou, Seth Lloyd, Francesco Caravelli, Simone Severini, Klas Markstrom, Phys. Rev. D 81, 104032 (2010) ; arXiv: 0911.5075
- Adiabatic approximation with exponential accuracy for many-body systems and quantum computation, D.A. Lidar, A.T. Rezakhani, A. Hamma, J. Math. Phys. 50, 102106 (2009), arxiv:quant-ph/0808.2697
- Decoherence and Entanglement Dynamics of Coupled Qubits, G. Campagnano, A. Hamma, U. Weiss, Physics Letters A 374 (2010) pp. 416-423, arxiv:quant-ph/0807.1987
- Topological Order Following a Quantum Quench, D.I. Tsomokos, A. Hamma, W. Zhang, S. Haas, R. Fazio, Phys. Rev. A 80, 060302(R) (2009), arXiv: 0909.0752
- Topological Entanglement Renyi Entropy and Reduced Density Matrix Structure, Steven T. Flammia, Alioscia Hamma, Taylor L. Hughes, Xiao-Gang Wen, Phys. Rev. Lett. 103, 261601 (2009), arXiv: 0909.3305
- Entanglement and area law with a fractal boundary, Alioscia Hamma, Daniel A. Lidar, Simone Severini, Phys. Rev. A 81, 010102 (Rapid Comunications) (2010), arxiv:quant-ph/0903.4444
- A.T. Rezakhani, W.-J. Kuo, A. Hamma, D.A. Lidar, P. Zanardi, Quantum Adiabatic Brachistochrone, Phys. Rev. Lett. 103, 080502 (2009), arXiv: 0905.2376
- Alioscia Hamma, Claudio Castelnovo, Claudio Chamon, Toric-boson model: Toward a topological quantum memory at finite temperature Phys. Rev. B 79, 245122 (2009) (Editors' Suggestions); arXiv: 0812.4622
- A.Hamma, F. Markopoulou, I. Premont-Schwarz, S. Severini Lieb-Robinson bounds and the speed of light from topological order Phys. Rev. Lett. 102, 017204 (2009); arXiv: 0808.2495v2
- Alioscia Hamma, Toufik Mansour, Simone Severini Diffusion on an Ising chain with kinks Physics Letters A, Volume 373, Issue 31, 20 July 2009, Pages 2622-2628 arXiv: 0806.4812v1
- Hidden entanglement at the Planck scale: loss of unitarity and the information paradox, Michele Arzano, Alioscia Hamma, Simone Severini, accepted in Modern Physics Letters A, arxiv:hep-th/0806.2145
- Damian F. Abasto, Alioscia Hamma, Paolo Zanardi, Fidelity analysis of topological quantum phase transitions, Phys. Rev. A 78, 010301(R), 2008., arXiv: 0803.2243
- A. Hamma, W. Zhang, S. Haas, D.A. Lidar (USC), Entanglement, fidelity and topological entropy in a quantum phase transition to topological order, Phys. Rev. B 77, 155111 (2008), arXiv: 0705.0026
- Alioscia Hamma, Daniel A. Lidar (Center for Quantum Information Science & Technology, USC), Adiabatic Preparation of Topological Order, Phys. Rev. Lett. 100, 030502 (2008), arXiv: quant-ph/0607145
- Alioscia Hamma, Radu Ionicioiu, Paolo Zanardi, Quantum entanglement in states generated by bilocal group algebras, Phys.Rev. A 72, 012324 (2005), arXiv: quant-ph/0504049
- Alioscia Hamma, Paolo Zanardi, Xiao Gang Wen, String and Membrane condensation on 3D lattices, Phys.Rev. B72 (2005) 035307, arxiv:cond-mat/411752
- Alioscia Hamma, Radu Ionicioiu, Paolo Zanardi, Bipartite entanglement and entropic boundary law in lattice spin systems, Phys. Rev. A 71, 022315 (2005), arXiv: quant-ph/0409073
- A.Hamma, R.Ionicioiu, P.Zanardi, Ground state entanglement and geometric entropy in the Kitaev's model, Phys.Lett. A 337, 22 (2005), arXiv: quant-ph/0406202
- Alioscia Hamma, Paolo Zanardi, Quantum entangling power of adiabatically connected hamiltonians, Phys. Rev. A 69, 062319 (2004), arXiv: quant-ph/0308131
- Gabor Halasz and Alioscia Hamma Probing topological order with Renyi entropy http://arxiv.org/abs/1206.4223
- Alioscia Hamma, S. Santra, and P. Zanardi Ensembles of physical states and random quantum circuits on graphs http://arxiv.org/abs/1204.0288
- Berry Phases and Quantum Phase Transitions, Alioscia Hamma, arXiv: quant-ph/0602091
- Advances in Quantum Computation, Edited by Kazem Mahdavi and Deborah Koslover, American Mathematical Society Contemporary Mathematics, Vol. 482 , p. 221-226 (2009)
- Proceedings of the NATO Advanced Study Institute, Quantum Computation and Quantum Information, 2-13 May 2005 Chania, Crete, Greece

- Topological order at finite temperature and the quest for quantum memory Invited speaker at workshop Topological Quantum Information, Scuola Normale Superiore, Pisa, Italy
- Lieb-Robinson bounds and the structure of correlations in quantum many body systems University of Illinois Urbana Champaign
- Topological order at finite temperature and the quest for quantum memory Invited speaker at International Conference on Frontier Topics in Nanostructures and Condensed Matter Theory, London Ontario, Canada
- Topological entanglement Renyi entropy and reduced density matrix structure, Simons Conference on New Trends in Quantum Computation\, Stony Brook, NY
- Revivals of a closed quantum system and Lieb-Robinson speed, Santa Fe Institute, Santa Fe NM
- Revivals of a closed quantum system and Lieb-Robinson speed, Boston University, MA
- Topological Renyi Entropy, Invited speaker at Quantum Engineering of States and Devices: Theory and Experiments, Universitatszentrum Obergurgl, Obergurgl, Austria
- Lieb-Robinson bounds and the structure of correlations in quantum many body systems, University of Toronto, Canada
- Short course about quantum phase transitions, entanglement, and topological order. Albert Einstein Institute -Potsdam, Germany
- How sound can protect quantum memory: The Toric-Boson model, University of Southern California
- The Toric-Boson model and quantum memory at finite temperature, University of Virginia
- Quantum Adiabatic Brachistochrone, University of New Brunswick, Fredericton NB, Canada
- Five lectures on topological order, Sherbrooke University, Quebec, Canada
- Topological Quantum Memory at Finite Temperature, Universita' di Perugia, Italy.
- Lieb-Robinson Bounds and The Speed of Light, Boston University
- Quantum evolution of space and matte, GRAVTUM II, Greece
- Lieb-Robinson bounds and the speed of light from topological order. Emergent Gravity conference, MIT
- A new error estimate for Adiabatic Quantum Computation, QEC07, USC Los Angeles CA
- Topological entropy and the entanglement description of Topological Order, California Institute of Technology, Pasadena, CA
- Entanglement description of topological order, University of Southern California, Los Angeles CA
- Entanglement in topologically order, UC Berkeley
- Topological Order and Entanglement, Conference on Representation Theory, Quantum Field Theory, Category Theory, Mathematical Physics and Quantum Information Theory, Tyler, TX
- Quantum phase transition from magnetic to topological order, APS March meeting, Denver USA
- Adiabatic Preparation of Topological Order, APS March meeting, Denver USA
- Adiabaticity in Open Quantum Systems, APS March meeting, Denver USA
- Three lectures on Quantum phase transitions, lattice gauge theories, and quantum order, Napoli, Italy
- The transition from magnetic to topological order, Perimeter Institute, Waterloo, Canada
- Topological adiabatic quantum computation, StationQ at university of Santa Barbara, USA
- Membrane condensed states and Topological Order, Max Planck Institute for Quantum Optics, Munich, Germany
- Group theoretic methods, entanglement, area law, Contributed talk at EQIS 2005, ERATO conference on Quantum Information Science, Tokyo, Japan
- Topological order with membrane condensation, Contributed talk at Quantum computing 2005, Algorithms, Physical Realizations and Beyond, Kinki University, Osaka, Japan
- Group Theoretic Methods, Entanglement and Area Law, University of Naples, Italy
- Group Theoretic Methods, Entanglement and Area Law, University of Innsbruck, Institute for Theoretical Physics
- Bipartite entanglement and area law with group-theoretic methods, Workshop on: Quantum Measurements and operations for cryptography and information processing, University of Pavia, Italy
- Bipartite entanglement and area law, TU Delft, Holland
- Bipartite entanglement and entropic boundary law in lattice spin systems, University of Barcelona, Spain
- Ground state entanglement in Kitaev's model, TOPQIP workshop, Institute for Scientific Interchange, Torino, Italy
- String and membrane condensation on 2D and 3D lattices, Poster session XXIII Meeting of theoretical physics and structure of matter, Fai della Paganella, Italy
- Entangling Power in adiabatically connected Hamiltonians, Massachussetts Institute of Technology
- PIRSA:09030047, Decoherence and Entanglement Dynamics of Coupled Qubits, 2009-03-23, Perimeter Institute Quantum Discussions
- Lieb-Robinson bounds and the speed of light

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