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Phys. Rev. A 71, 032312 (2005) [11 pages]

Perfect transfer of arbitrary states in quantum spin networks

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Matthias Christandl1 *, Nilanjana Datta2 †, Tony C. Dorlas3 ‡, Artur Ekert1,4 §, Alastair Kay1 **, and Andrew J. Landahl5,6 ††
1Centre for Quantum Computation, DAMTP, Centre for Mathematical Sciences, 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
3School of Theoretical Physics, Dublin Institute for Advanced Studies, 10 Burlington Road, Dublin 4, Ireland
4Department of Physics, National University of Singapore, Singapore 117542, Singapore
5Center for Bits and Atoms, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
6HP Labs, Palo Alto, California 94304-1126, USA

Received 2 November 2004; published 14 March 2005

We propose a class of qubit networks that admit perfect state transfer of any two-dimensional quantum state in a fixed period of time. We further show that such networks can distribute arbitrary entangled states between two distant parties, and can, by using such systems in parallel, transmit the higher-dimensional systems states across the network. 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 2  log3N 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. This paper expands and extends the work done by Christandl et al., Phys. Rev. Lett. 92, 187902 (2004).


©2005 The American Physical Society

URL: http://link.aps.org/doi/10.1103/PhysRevA.71.032312
DOI: 10.1103/PhysRevA.71.032312
PACS: 03.67.Hk

* Electronic address: matthias.christandl@qubit.org
† Electronic mail: n.datta@statslab.cam.ac.uk
‡ Electronic mail: dorlas@stp.dias.ie
§ Electronic mail: artur.ekert@qubit.org
** Electronic mail: alastair.kay@qubit.org
†† Electronic mail: alandahl@mit.edu

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