Non-equilibrium anti-Stokes Raman spectroscopy for investigating Higgs modes in superconductors

Area of Science:

• Condensed Matter Physics
• High-Energy Physics
• Quantum Mechanics

Background:

• The Anderson-Higgs mechanism, predating electroweak symmetry breaking, explains the Meissner effect in superconductors.
• Spontaneous symmetry-breaking in superconductors shifts phase modes to higher energies, resulting in a Higgs mode governing low-energy excitations.
• The Bardeen-Cooper-Schrieffer-like Meissner effect indicates a macroscopic quantum condensate where photons gain mass, mirroring high-energy physics.

Purpose of the Study:

• To introduce and utilize an innovative spectroscopic technique for studying Higgs mode symmetries and energies.
• To investigate Higgs modes in the high-temperature superconductor Bismuth Strontium Calcium Copper Oxide (Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8}$) following a soft quench.
• To establish a quantitative description of single-particle and two-particle channels within a Bardeen-Cooper-Schrieffer weak-coupling model.

Main Methods:

• Employed a novel spectroscopic technique involving a soft quench of the Mexican-Hat potential in Bi$_{2}$Sr$_{2}$CaCu$_{2}$O$_{8}$.
• Utilized an initial laser pulse to induce population inversion, leading to an anti-Stokes Raman-scattering signal.
• Applied Ginzburg-Landau theory and a Bardeen-Cooper-Schrieffer weak-coupling model for quantitative analysis.

Main Results:

• Observed polarization-dependent Higgs modes, consistent with the anti-Stokes Raman-scattering signal.
• Established a connection between Higgs mode energy and Cooper-pair coherence length within Ginzburg-Landau theory.
• Developed a quantitative and coherent description of single-particle and two-particle channels.

Conclusions:

• The study demonstrates a novel spectroscopic approach for Higgs Spectroscopy in quantum condensates.
• The findings provide a unique pathway to control and explore Higgs physics in superconductors.
• This research bridges the gap between condensed matter phenomena and high-energy physics concepts.