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arXiv · 1702.07785

Probing weak dipole-dipole interaction using phase-modulated non-linear spectroscopy

Zeng-Zhao Li·Lukas Bruder·Frank Stienkemeier·Alexander Eisfeld
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Abstract

Phase-modulated non-linear spectroscopy with higher harmonic demodulation has recently been suggested to provide information on many-body excitations. In the present work we theoretically investigate the application of this method to infer the interaction strength between two particles that interact via weak dipole-dipole interaction. To this end we use full numerical solution of the Schrödinger equation with time-dependent pulses. For interpretation purpose we also derive analytical expressions in perturbation theory. We find one can detect dipole-dipole interaction via peak intensities (in contrast to line-shifts which typically are used in conventional spectroscopy). We provide a detailed study on the dependence of these intensities on the parameters of the laser pulse and the dipole-dipole interaction strength. Interestingly, we find that there is a phase between the first and second harmonic demodulated signal, whose value depends on the sign of the dipole-dipole interaction.

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Zeng-Zhao Li, Lukas Bruder, Frank Stienkemeier, Alexander Eisfeld. 2017-05-26. Probing weak dipole-dipole interaction using phase-modulated non-linear spectroscopy. https://doi.org/10.1103/physreva.95.052509

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