Thermoelectricity of cold ions in optical lattices

We study analytically and numerically the thermoelectric properties of cold ions placed in an optical lattice. Our results show that the transition from sliding to pinned phase takes place at a certain critical amplitude of lattice potential being similar to the Aubry transition for the Frenkel–Kontorova model. We show that this critical amplitude is proportional to the cube of ion density that allows to perform experimental realization of this system at moderate lattice amplitudes. We show that the Aubry phase is characterized by the dimensionless Seebeck coefficient about 50 and the figure of merit being around 8. We propose possible experimental investigations of such system with cold ions and argue that the experiments with electrons on liquid helium surface can also help to understand its unusual properties. The obtained results represent also a challenge for modern methods of quantum chemistry and material science. Graphical abstract:

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