Eur. Phys. J. Special Topics 222, 1223-1239 (2013)
https://doi.org/10.1140/epjst/e2013-01917-9

Regular Article

Investigating pairing interactions with coherent charge fluctuation spectroscopy

¹ Institute for Complex Systems-CNR and Physics Department, Sapienza, University of Rome, Piazzale Aldo Moro 5, 00185 Rome, Italy
² Laboratory for Ultrafast Microscopy and Electron Scattering, ICMP, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
³ Laboratory of Ultrafast Spectroscopy, ISIC, Ecole Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland

^a e-mail: jose.lorenzana@roma1.infn.it

Received: 18 March 2013
Revised: 12 May 2013
Published online: 15 July 2013

Abstract

It has been recently demonstrated that a pump pulse can generate coherent charge fluctuations in a superconductor through a stimulated Raman process [Mansart, et al., Proc. Natl. Acad. Sci. USA 110, 4539 (2013)]. Here, we present a tutorial review of the basic phenomena involved and show how the technique bears a strong analogy with nuclear magnetic resonance and electron paramagnetic resonance. The reflectivity of the system gets modulated by the coherent charge fluctuation of the condensate. A resonance at the Mott scale allows to identify a high-energy excitation which is coupled to the superconducting quasiparticles.