Higgs mode stabilization by photoinduced long-range interactions in a superconductor

We show that low-lying excitations of a 2D Bardeen-Cooper-Schrieffer superconductor are significantly altered when coupled to an externally driven cavity, which induces controllable long-range attractive interactions between the electrons. We find that they combine nonlinearly with intrinsic local interactions to increase the Bogoliubov quasiparticle excitation energies, thus enlarging the superconducting gap. The long-range nature of the driven-cavity-induced attraction qualitatively changes the collective excitations of the superconductor. Specifically, they lead to the appearance of additional collective excitations of the excitonic modes. Furthermore, the Higgs mode is pushed into the gap and now lies below the Bogoliubov quasiparticle continuum such that it cannot decay into quasiparticles. This way, the Higgs mode's lifetime is greatly enhanced.

Automated summary

The coupling between a 2D Bardeen-Cooper-Schrieffer superconductor and an externally driven cavity alters the low-lying excitations and increases the superconducting gap. The driven-cavity-induced long-range attraction changes the collective excitations of the superconductor, leading to the appearance of additional excitonic modes and enhancing the lifetime of the Higgs mode.