Bypassing the energy-time uncertainty in time-resolved photoemission

Francesco Randi, Daniele Fausti, and Martin Eckstein
Phys. Rev. B 95, 115132 – Published 16 March 2017

Abstract

The energy-time uncertainty is an intrinsic limit for time-resolved experiments imposing a tradeoff between the duration of the light pulses used in experiments and their frequency content. In standard time-resolved photoemission, this limitation maps directly onto a tradeoff between the time resolution of the experiment and the energy resolution that can be achieved on the electronic spectral function. Here we propose a protocol to disentangle the energy and time resolutions in photoemission. We demonstrate that dynamical information on all time scales can be retrieved from time-resolved photoemission experiments using suitably shaped light pulses of quantum or classical nature. As a paradigmatic example, we study the dynamical buildup of the Kondo peak, a narrow feature in the electronic response function arising from the screening of a magnetic impurity by the conduction electrons. After a quench, the electronic screening builds up on timescales shorter than the inverse width of the Kondo peak and we demonstrate that the proposed experimental scheme could be used to measure the intrinsic time scales of such electronic screening. The proposed approach provides an experimental framework to access the nonequilibrium response of collective electronic properties beyond the spectral uncertainty limit and will enable the direct measurement of phenomena such as excited Higgs modes and, possibly, the retarded interactions in superconducting systems.

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  • Received 28 April 2016
  • Revised 17 February 2017

DOI:https://doi.org/10.1103/PhysRevB.95.115132

©2017 American Physical Society

Physics Subject Headings (PhySH)

Condensed Matter, Materials & Applied Physics

Authors & Affiliations

Francesco Randi1,2, Daniele Fausti1,3, and Martin Eckstein2,4,*

  • 1Department of Physics, Università degli Studi di Trieste, 34127 Trieste, Italy
  • 2Max Planck Institute for the Structure and Dynamics of Matter, 22761 Hamburg, Germany
  • 3Sincrotrone Trieste SCpA, 34127 Basovizza, Italy
  • 4University of Hamburg-CFEL, 22761 Hamburg, Germany

  • *martin.eckstein@mpsd.cfel.de

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Vol. 95, Iss. 11 — 15 March 2017

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