From Majorana fermions to topological order

Journal article (2012)

Authors

B.M. Terhal Rheinisch-Westfälische Technische Hochschule
Fabian Hassler Rheinisch-Westfälische Technische Hochschule
David P. DiVincenzo Forschungszentrum Jülich, Rheinisch-Westfälische Technische Hochschule
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Published Date

2012

Language

English

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Abstract

We consider a system consisting of a 2D network of links between Majorana fermions on superconducting islands. We show that the fermionic Hamiltonian modeling this system is topologically ordered in a region of parameter space: we show that Kitaev's toric code emerges in fourth-order perturbation theory. By using a Jordan-Wigner transformation we can map the model onto a family of signed 2D Ising models in a transverse field where the signs, ferromagnetic or antiferromagnetic, are determined by additional gauge bits. Our mapping allows an understanding of the nonperturbative regime and the phase transition to a nontopological phase. We discuss the physics behind a possible implementation of this model and argue how it can be used for topological quantum computation by adiabatic changes in the Hamiltonian.