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Our work is in quantum information, ranging from `Models of quantum computation' and quantum faulttolerance to entanglement theory and manybody physics. For more information click here.
Featured publication: Experimental demonstration of topological error correction. [Posted June 7, 2012] Here we report the experimental demonstration of topological error correction with an eightphoton cluster state. We show that a correlation can be protected against a single error on any quantum bit. Also, when all quantum bits are simultaneously subjected to errors with equal probability, the effective error rate can be significantly reduced. Our work demonstrates the viability of topological error correction for faulttolerant quantum information processing.
The present experiment uses an 8qubit cluster state which shares topological features with its larger (potentially much larger) cousin, the threedimensional cluster state. A 3D cluster state is for measurementbased quantum computation (MBQC) what the Kitaev surface code is for the circuit model: a faulttolerant fabric in which protected quantum gates can be implemented in a topological fashion. The present experiment demonstrates the faulttolerance properties, not yet the encoded quantum gates. For the latter, larger cluster states will be required in future experiments. The smallest possible setting to demonstrate topological errorcorrection with cluster states requires 8 qubits, which was just in reach of the present photonbased experiment.
Journal Reference: XingCan Yao et al, Experimental demonstration of topological error correction, Nature 482, 489 (2012).
Also see James D. Franson, Quantum computing: A topological route to error correction, Nature 482, News and Views, (2012).
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Topological error correction with cluster states. (left) Measurement of the error in the topologically protected correlation of the cluster state (0: perfect correlation, 0.5: no correlation, 1: perfect anticorrelation), vs. the one qubit error rate. The local errors are subjected to the cluster state on purpose, with varying strength. The black curve is the theory prediction for the strength of the correlation vs local error rate, if no error correction is performed, and the red dashed curve is for the same correlation with error correction performed. The dots represent the measured data. For small error probabilities, topological error correction significantly reduces logical error. (right) What do the 8qubit cluster state used in the experiment and a large 3D cluster state have in common?  Both can be described by an underlying threedimensional chain complex. Their topological error protection derives from the homology properties of these complexes. 
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Robert Raussendorf 

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Poya Haghnegahdar 

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Philippe Allard Guerin 

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Navid Siami 

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Arman Zaribafiyan 
TzuChieh Wei, faculty at Stony Brook, NY, USA
Pradeep Sarvepalli, faculty at IIT Madras, Chennai, India
Leon Loveridge, University of Oxford, UK
Raouf Dridi
Vijay Singh
Angela Ruthven (UBC Enginerring Physics)
Len Goff (UBC Economics)
Matthew Scholte
Cedric Lin (MIT),
Matthew Low (University of Chicago),
Philip Ketterer (Ludwig Maximilians University Munich, Germany),
Philip Allen Mar (University of Toronto),
Cihan Okay (University of Western Ontario)
C. Monroe, R. Raussendorf, A. Ruthven, K. Brown, P. Maunz, L.M. Duan and J. Kim, Large Scale Modular Quantum Computer Architecture with Atomic Memory and Photonic Interconnects, arXiv:1208.0391
P. Sarvepalli and P. Wocjan, Quantum Algorithms for OneDimensional Infrastructures, arXiv:1106.6347 (2011).
P. Sarvepalli, Quantum Codes and Symplectic Matroids, arXiv:1104.1171 (2011).
Robert Raussendorf, Quantum computation, discreteness, and contextuality, arXiv:0907.5449 (2009).
Leonard Goff and Robert Raussendorf, Classical simulation of measurementbased quantum computation with highergenus surface code states, Phys. Rev. A 86, 042301 (2012).
R. Raussendorf, P. Sarvepalli, T.C. Wei, P. Haghnegahdar, Symmetry constraints on tem poral order in measurementbased quantum computation, Electronic Proceedings in Theoretical Computer Science (EPTCS) 95, pp. 219250 (2012).
TzuChieh Wei, Ian Affleck, Robert Raussendorf, The 2D AKLT state on the honeycomb lattice is a universal resource for quantum computation, Phys. Rev. A 86, 032328 (2012).
R. Raussendorf, Key concepts in faulttolerant quantum computation, Philosophical transactions. Series A, Mathematical, physical, and engineering sciences 370, 454 (2012).
Robert Raussendorf and TzuChieh Wei, Quantum Computation by Local Measurement, Annu. Rev. Condens. Matter Phys 3, 239 (2012).
XingCan Yao, TianXiong Wang, HaoZe Chen, WeiBo Gao, Austin G. Fowler, Robert Raussendorf, ZengBing Chen, NaiLe Liu, ChaoYang Lu, YouJin Deng, YuAo Chen, and JianWei Pan, Experimental demonstration of topological error correction, Nature 482, 489 (2012).
P. Sarvepalli and R. Raussendorf, Efficient decoding of topological color codes, Phys. Rev. A 85, 022317 (2012).
Roman Orus and TzuChieh Wei, Geometric entanglement of onedimensional systems: bounds and scalings in the thermodynamic limit, Quantum Information and Computation Vol. 11, No. 7, 563 (2011).
Jingfu Zhang, TzuChieh Wei, and Raymond Laflamme, Experimental Quantum Simulation of Entanglement in Manybody Systems, Phys. Rev. Lett. 107, 010501 (2011).
Ying Li, Daniel E. Browne, Leong Chuan Kwek, Robert Raussendorf, and TzuChieh Wei, Thermal States as Universal Resources for Quantum Computation with Alwayson Interactions, Phys. Rev. Lett. 107, 060501 (2011).
P. Sarvepalli, Topological Color Codes over Higher Alphabet. In Proc. of IEEE Information Theory Workshop, Dublin, Ireland Aug 30Sep 3, 2010.
P. Sarvepalli, R. Raussendorf. Local equivalence of surface code states. TQC'10 Proceedings of the 5th conference on Theory of quantum computation, communication, and cryptography. Lecture Notes in Computer Science, 2011, Volume 6519/2011, 4762.
Pradeep Sarvepalli, Entropic Inequalities for a Class of Quantum Secret Sharing States, Phys. Rev. A 83, 042303 (2011).
Pradeep Sarvepalli, Bounds on the Information Rate of Quantum Secret Sharing Schemes, Phys. Rev. A 83, 042324 (2011).
TzuChieh Wei, Johnathan Lavoie, and Rainer Kaltenbaek, Creating multiphoton polarization boundentangled states, Phys. Rev. A 83, 033839 (2011).
Lin Chen, Huangjun Zhu, and TzuChieh Wei, Connections of geometric measure of entanglement of pure symmetric states to quantum state estimation Phys. Rev. A 83, 012305 (2011).
TzuChieh Wei, Smitha Vishveshwara and Paul M. Goldbart, Global geometric entanglement in transversefield XY spin chains: finite and infinite systems, Quantum Inf. Comput. 11, 03260354 (2011)
TzuChieh Wei, Ian Affleck, Robert Raussendorf, The 2D AKLT state is a universal quantum computational resource, Physical Review Letters 106, 070501 (2011).
P. Sarvepalli, Topological Color Codes over Higher Alphabet. In Proc. of IEEE Information Theory Workshop, Dublin, Ireland Aug 30Sep 3, 2010.
R. Raussendorf, Shaking up ground states Nature Physics 6, 840 (2010); News and Views on J. Lavoie et al., Optical oneway quantum computing with a simulated valencebond solid , Nature Physics 6, 850 (2010).
Roman Orus and TzuChieh Wei, Visualizing elusive phase transitions with geometric entanglement, Phys. Rev. B 82, 155120 (2010).
Wade DeGottardi, TzuChieh Wei, Victoria Fernandez, and Smitha Vishveshwara, Accessing nanotube bands via crossed electric and magnetic fields, Phys. Rev. B 82, 155411 (2010).
Pradeep Sarvepalli and Robert Raussendorf, On Local Equivalence, Surface Code States and Matroids, Phys. Rev. A 82, 022304 (2010).
Matthew Killi, TzuChieh Wei, Ian Affleck, Arun Paramekanti, TomonagaLuttinger liquid physics in gated bilayer graphene , Phys. Rev. Lett. 104, 216406 (2010).
TzuChieh Wei, Entanglement under the renormalizationgroup transformations on quantum states and in quantum phase transitions , Phys. Rev. A 81, 062313 (2010).
TzuChieh Wei, Exchange symmetry and global entanglement and full separability , Phys. Rev. A 81, 054102 (2010).
Pradeep Sarvepalli and Robert Raussendorf, Matroids and Quantum Secret Sharing Schemes, Phys. Rev. A 81, 052333 (2010).
Pradeep Sarvepalli and Andreas Klappenecker, Degenerate quantum codes and the quantum Hamming bound, Phys. Rev. A 81, 032318 (2010).
TzuChieh Wei, Michele Mosca, and Ashwin Nayak, Interacting boson problems can be QMAhard, Phys. Rev. Lett. 104, 040501 (2010).
M. Van den Nest, W. Duer, R. Raussendorf, H. J. Briegel, Quantum algorithms for spin models and simulable gate sets for quantum computation, Phys. Rev. A 80, 052334 (2009).
Robert Raussendorf, Measurementbased quantum computation with cluster states ( PhD thesis, LudwigMaximiliansUniversitaet Munich, 2003), Int. J. of Quantum Information 7, 1053  1203 (2009).
Sayatnova Tamaryan, TzuChieh Wei, and DaeKil Park, Maximally entangled threequbit states via geometric measure of entanglement, Phys. Rev. A 80, 052315 (2009).
Pradeep Kiran Sarvepalli and Andreas Klappenecker, Sharing classical secrets with CalderbankShorSteane codes, Phys. Rev. A 80, 022321 (2009).
H. J. Briegel, D. E. Browne, W. Duer, R. Raussendorf and M. Van den Nest, Measurementbased quantum computation, Nature Physics 5, 19 (2009).