Abstract-Superconducting pair-breaking under intense sub-gap terahertz radiation

Applied Physics Letters

Jie Tian, Jack Zuber, Sunchao Huang, Chao Zhang

The relation between the ratio of superconducting carriers and energy gap (a), temperature (b), and parameters 
(E/ω)2${(E/\omega )}^2$(c).

https://aip.scitation.org/doi/abs/10.1063/1.5098045

We study the effect of a strong and low frequency (ω < Δ, the superconducting gap) electrical field on a superconducting state. It is found that the superconducting gap decreases with the field intensity and wavelength. The physical mechanism for this dependence is the multiphoton absorption by a superconducting electron. By constructing the state of a superconducting electron dressed by photons, we determined the dependence of the superconducting gap on E/ω$E/\omega$ and temperature. We show that the critical temperature is determined by the parameter E/ω$E/\omega$ which is distinct from that induced by the heating effect. The result is consistent with experimental findings. This result can be applied to study terahertz nonlinear superconducting metamaterials.