Robert Raussendorf's Quantum Information group at UBC Physics

Group members


  • Quantum Information and Computation
  • QI and quantum foundations
  • Quantum fault-tolerance

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Our work is in quantum information, ranging from `Models of quantum computation' and quantum fault-tolerance to entanglement theory and many-body 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 eight-photon 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 fault-tolerant quantum information processing.

The present experiment uses an 8-qubit cluster state which shares topological features with its larger (potentially much larger) cousin, the three-dimensional cluster state. A 3D cluster state is for measurement-based quantum computation (MBQC) what the Kitaev surface code is for the circuit model: a fault-tolerant fabric in which protected quantum gates can be implemented in a topological fashion. The present experiment demonstrates the fault-tolerance 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 error-correction with cluster states requires 8 qubits, which was just in reach of the present photon-based experiment.

Journal Reference: Xing-Can 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).


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 anti-correlation), 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 8-qubit cluster state used in the experiment and a large 3D cluster state have in common? - Both can be described by an underlying three-dimensional chain complex. Their topological error protection derives from the homology properties of these complexes.

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Group members

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Robert Raussendorf
Associate Professor
Hennings 338, Tel.: (604) 822-3253
email: raussen[at]phas[dot]ubc[dot]ca

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Poya Haghnegahdar
Graduate Student (PhD)
email: phaghneg[at]phas[dot]ubc[dot]ca

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Philippe Allard Guerin
Graduate student (Masters)
email: pallard[at]phas[dot]ubc[dot]ca

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Navid Siami
Graduate student (Masters)
email: navidsiami[at]gmail[dot]com

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Arman Zaribafiyan
Graduate Student (PhD)
email: zaribafiyan[at]gmail[dot]com

Former group members


Tzu-Chieh 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)

Group publications


2012 - Journal publications

2011 - Journal publications

2010 - Journal publications

2009 - Journal publications

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