Higgs mode in (2 + 1)-dimensional O(2) model

In this paper, we investigate the spectral functions of the Higgs mode in [Formula: see text] model, which can be experimentally realized in a two-dimensional Bose gas. Zero temperature limit is considered. Our calculation fully includes the 2-loop contributions. Peaks show up in the spectral functions of both the longitudinal and the scalar susceptibilities. Thus, this model cannot explain the disappearance of the response at the weak interaction limit. Neither it can explain the similarity between the longitudinal and the scalar susceptibilities in the visibility of the Higgs mode. A possible lower peak at about [Formula: see text] is also noted.

Effective field theory of the Higgs mode in a two-dimensional dilute Bose gas

In this paper, we investigate the spectral function of the Higgs mode in a two-dimensional Bose gas by using the effective field theory in the zero-temperature limit. Our approach explains the experimental feature that the peak of the spectral function is a soft continuum rather than a sharp peak, broadens and vanishes in the superfluid phase, which cannot be explained in terms of the [Formula: see text] model. We also find that the scalar susceptibility is the same as the longitudinal susceptibility.

Harnessing ultraconfined graphene plasmons to probe the electrodynamics of superconductors

We show that the Higgs mode of a superconductor, which is usually challenging to observe by far-field optics, can be made clearly visible using near-field optics by harnessing ultraconfined graphene plasmons. As near-field sources we investigate two examples: graphene plasmons and quantum emitters. In both cases the coupling to the Higgs mode is clearly visible. In the case of the graphene plasmons, the coupling is signaled by a clear anticrossing stemming from the interaction of graphene plasmons with the Higgs mode of the superconductor. In the case of the quantum emitters, the Higgs mode is observable through the Purcell effect. When combining the superconductor, graphene, and the quantum emitters, a number of experimental knobs become available for unveiling and studying the electrodynamics of superconductors.