Piotr T.
Grochowski
Center for Theoretical Physics PAS and ICFO - Institute of Photonic Sciences, The Barcelona Institute of Science and Technology
Superconductivity induces dynamics with minimized electron-electron scattering rates, which allows the generation of extremely high currents inside the solids.
Low-temperature superconductors are well described by the BCS theory, but high-tech cryogenic devices are needed to reach the required temperatures below 10 K.
On the other hand, superconducting states can already be accessed at liquid Nitrogen temperatures of 77 K by using high-temperature superconductors.
In this work we demonstrate that the nonlinear electron dynamics in the high-temperature superconductor YBCO lead to an exponential growth of the surface harmonic yield through the superconducting phase.
As a proof of principle, harmonic intensity was measured from 80 K to 300 K, showing significant enhancement throughout the phase transition.
The reduced spectral blue-shift measured in the superconducting phase highlights the scalability of the process to higher pump intensities.
A novel strong-field quantum model is proposed for the prediction of the harmonics in the superconducting states, corroborating the measured harmonic enhancement.
The compactness and the demonstrated scalability of the high harmonic intensities in the superconducting phase, makes it a key enabling tool for efficient applications of harmonic generation in the UV regime for intense ultraviolet pulse generation.
