Incoherent Excitation of Coherent Higgs Oscillations in Superconductors

TL;DR

This paper theoretically explores how incoherent light pulses can excite Higgs oscillations in superconductors, revealing that the excitation amplitude depends on the total quasiparticles excited, linked to a universal cascade process.

Contribution

It introduces a theoretical framework for incoherent excitation of Higgs modes in superconductors and identifies the key parameter controlling the excitation amplitude.

Findings

Higgs oscillations can be excited incoherently in superconductors.

The excitation amplitude depends on the total number of quasiparticles excited.

A universal quasiparticle cascade shape underpins the excitation process.

Abstract

We investigate theoretically the excitation of Higgs oscillations of the order parameter in superconductors by incoherent short pulses of light with frequency much larger than the superconducting gap. The excitation amplitude of the Higgs mode is controlled by a single parameter which is determined by the total number of quasiparticles excited by the pulse. This fact can be traced back to the universality of the shape of the light-induced quasiparticle cascade at energy below the Debye frequency and above the gap.