Quantum fluctuations and the emergence of in-gap Higgs mode in superconductors

Fuente: arXiv
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Main Authors: Tian, Sida, Tsuji, Naoto, Manske, Dirk
Format: Preprint
Published: 2026
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author Tian, Sida
Tsuji, Naoto
Manske, Dirk
author_facet Tian, Sida
Tsuji, Naoto
Manske, Dirk
contents We extend the well-established action of the Higgs mode in $s$-wave superconductors to include quantum fluctuations (QFs). We find that already one-loop quantum corrections to the Higgs propagator shift its eigenfrequency below the superconducting energy gap $2Δ$. Consequently, the Higgs mode appears as an undamped pole below the quasiparticle continuum, leading to drastically sharper experimental signatures. We demonstrate this by calculating two characteristic fingerprints of the Higgs mode, namely in Third Harmonic Generation (THG) and inelastic Raman scattering signals. More generally, gaps measured in $s$-wave superconductors with different experimental techniques (such as scanning tunneling microscope and Raman scattering) may be different due to fluctuation corrections. Since already arbitrarily weak QFs lead to the shift and to the new pole, our results shed some light on other amplitude modes even for systems with weak QFs, including charge density waves, (anti-) ferromagnets, or cold atom fermionic condensates.
format Preprint
id arxiv_https___arxiv_org_abs_2604_15120
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Quantum fluctuations and the emergence of in-gap Higgs mode in superconductors
Tian, Sida
Tsuji, Naoto
Manske, Dirk
Superconductivity
We extend the well-established action of the Higgs mode in $s$-wave superconductors to include quantum fluctuations (QFs). We find that already one-loop quantum corrections to the Higgs propagator shift its eigenfrequency below the superconducting energy gap $2Δ$. Consequently, the Higgs mode appears as an undamped pole below the quasiparticle continuum, leading to drastically sharper experimental signatures. We demonstrate this by calculating two characteristic fingerprints of the Higgs mode, namely in Third Harmonic Generation (THG) and inelastic Raman scattering signals. More generally, gaps measured in $s$-wave superconductors with different experimental techniques (such as scanning tunneling microscope and Raman scattering) may be different due to fluctuation corrections. Since already arbitrarily weak QFs lead to the shift and to the new pole, our results shed some light on other amplitude modes even for systems with weak QFs, including charge density waves, (anti-) ferromagnets, or cold atom fermionic condensates.
title Quantum fluctuations and the emergence of in-gap Higgs mode in superconductors
topic Superconductivity
url https://arxiv.org/abs/2604.15120