Volume 95, Number 5, September 2011
|Number of page(s)||5|
|Published online||09 August 2011|
Quantum phase transition between cluster and antiferromagnetic states
Center for Quantum Technology, National University of Singapore - 117542 Singapore, Singapore
2 CNR-MATIS-IMM and Dipartimento di Fisica e Astronomia, Università di Catania C/O ed. 10, viale A. Doria 6, I-95125 Catania, Italy, EU
3 NEST, Scuola Normale Superiore and CNR-INFM - Piazza dei Cavalieri 7, I-56126 Pisa, Italy, EU
4 Perimeter Institute for Theoretical Physics - 31 Caroline St. N,Waterloo ON, N2L 2Y5, Canada
5 Dipartimento di Fisica and MECENAS, Università di Bari - I-70126 Bari, Italy, EU
6 INFN, Sezione di Bari - I-70126 Bari, Italy, EU
7 Department of Physics, National University of Singapore - 2 Science Drive 3, 117542 Singapore, Singapore
8 Department of Physics, University of Oxford, Clarendon Laboratory - Oxford, OX1 3PU, UK, EU
Accepted: 10 July 2011
We study a Hamiltonian system describing a three–spin-1/2 cluster-like interaction competing with an Ising-like exchange. We show that the ground state in the cluster phase possesses symmetry protected topological order. A continuous quantum phase transition occurs as result of the competition between the cluster and Ising terms. At the critical point the Hamiltonian is self-dual. The geometric entanglement is also studied and used to investigate the quantum phase transition. Our findings in one dimension corroborate the analysis of the two-dimensional generalization of the system, indicating, at a mean-field level, the presence of a direct transition between an antiferromagnetic and a valence bond solid ground state.
PACS: 03.65.Ud – Entanglement and quantum nonlocality (e.g. EPR paradox, Bell's inequalities, GHZ states, etc.) / 03.65.Ta – Foundations of quantum mechanics; measurement theory / 03.67.-a – Quantum information
© EPLA, 2011
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