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arXiv · 1812.09222

Noise Correlations in time- and angular-resolved photoemission spectroscopy

Christopher Stahl·Martin Eckstein
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Abstract

In time-resolved photoemission experiments, more than one electron can be emitted from the solid by a single ultra-short pulse. We theoretically demonstrate how correlations between the momenta of outgoing electrons relate to time-dependent two-particle correlations in the solid. This can extend the scope of time- and angular-resolved photoemission spectroscopy to probe superconducting and charge density fluctuations in systems without long-range order, and to reveal their dynamics independent of the electronic gap and thus unrestricted by the energy-time uncertainty. The proposal is illustrated for superconductivity in a BCS model. An impulsive perturbation can quench the gap on ultrafast timescales, while non-equilibrium pairing correlations persist much longer, even when electron-electron scattering beyond mean-field theory is taken into account. There is thus a clear distinction between a dephasing of the Cooper pairs and the thermalization into the normal state. While a measurement of the gap would be blind to such pairing correlations, they can be revealed by the angular correlations in photoemission.

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Christopher Stahl, Martin Eckstein. 2018-12-21. Noise Correlations in time- and angular-resolved photoemission spectroscopy. https://doi.org/10.1103/physrevb.99.241111

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