A toolbox for lattice-spin models with polar molecules


There is growing interest in states of matter with topological order. These are characterized by highly stable ground states robust to perturbations that preserve the topology, and which support excitations with so-called anyonic statistics. Topologically ordered states can arise in two-dimensional lattice-spin models, which were proposed as the basis for a new class of quantum computation. Here, we show that the relevant hamiltonians for such spin lattice models can be systematically engineered with polar molecules stored in optical lattices, where the spin is represented by a single-valence electron of a heteronuclear molecule. The combination of microwave excitation with dipole–dipole interactions and spin–rotation couplings enables building a complete toolbox for effective two-spin interactions with designable range, spatial anisotropy and coupling strengths significantly larger than relevant decoherence rates. Finally, we illustrate two models: one with an energy gap providing for error-resilient qubit encoding, and another leading to topologically protected quantum memory.

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Figure 1: Example anisotropic spin models that can be simulated with polar molecules trapped in optical lattices.
Figure 2: Movre–Pichler potentials for a pair of molecules as a function of their separation r.
Figure 3: Design and verification of noise-protected ground states arising from a simulation of Hspin(I).
Figure 4: Implementation of spin model Hspin(II).


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A.M. thanks W. Ernst, and P.Z. thanks T. Calarco, L. Faoro, M. Lukin, and D. Petrov for helpful discussions. This work was supported by the Austrian Science Foundation, the European Union, OLAQUI, SCALA and the Institute for Quantum Information.

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Correspondence to A. Micheli.

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Micheli, A., Brennen, G. & Zoller, P. A toolbox for lattice-spin models with polar molecules. Nature Phys 2, 341–347 (2006). https://doi.org/10.1038/nphys287

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