Dynamics of phase coherence in superconducting cuprates upon mid-infrared photoexcitation*

Superconducting fluctuations in optimally-doped cuprates are known to survive well above the critical temperature, making these systems a perfect playground to investigate the possibility of transiently controlling superconductivity through ultrashort light pulses. While it has been widely shown that high photon energy electromagnetic fields melt the superconducting phase [1], there are evidences that mid-infrared photoexcitation can trigger the onset of superconductivity in regions of the phase diagram in which the system is not superconducting at the equilibrium [2,3]. We performed measurements on optimally-doped Y-Bi2212 by a 3-pulse technique which allows to disentangle these two effects. The approach is based on selectively destroying the superconducting state using a visible pump, and then further exciting the sample by means of a mid-infrared source. By probing the system through a broadband supercontinuum, we reveal the details of the transient dynamics of the condensate phase coherence solely driven by mid-infrared pulses with photon energy close to the superconducting gap.
[1] Giannetti C. et al., Advances in Physics 65, 58-238 (2016)
[2] Fausti D. et al., Science 331, 6014 189-191 (2011)
[3] Giusti F. et al., Phys. Rev. Lett. 122, 067002 (2019)