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Phys. Rev. Lett. 92, 187902 (2004) [4 pages]

Perfect State Transfer in Quantum Spin Networks

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Matthias Christandl1 *, Nilanjana Datta2, Artur Ekert1,3, and Andrew J. Landahl4,5
1Centre for Quantum Computation, Centre for Mathematical Sciences, DAMTP, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom
2Statistical Laboratory, Centre for Mathematical Science, University of Cambridge, Wilberforce Road, Cambridge CB3 0WB, United Kingdom
3Department of Physics, National University of Singapore, Singapore 117 542, Singapore
4Center for Bits and Atoms, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
5HP Labs, Palo Alto, California 94304-1126, USA

Received 22 September 2003; published 4 May 2004

We propose a class of qubit networks that admit the perfect state transfer of any quantum state in a fixed period of time. Unlike many other schemes for quantum computation and communication, these networks do not require qubit couplings to be switched on and off. When restricted to N-qubit spin networks of identical qubit couplings, we show that 2log⁡3N is the maximal perfect communication distance for hypercube geometries. Moreover, if one allows fixed but different couplings between the qubits, then perfect state transfer can be achieved over arbitrarily long distances in a linear chain.


©2004 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevLett.92.187902
DOI: 10.1103/PhysRevLett.92.187902
PACS: 03.67.Hk, 03.67.Pp, 05.50.+q

* Electronic address: matthias.christandl@qubit.org

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