High-Harmonic Generation Approaching the Quantum Critical Point of Strongly Correlated Systems

Area of Science:

• Condensed Matter Physics
• Quantum Optics
• Materials Science

Background:

• Strong laser fields interacting with correlated quantum systems can lead to complex phenomena like high-harmonic generation (HHG).
• Understanding HHG is crucial for developing advanced light sources and probing exotic quantum phases.

Purpose of the Study:

• To investigate high-harmonic generation (HHG) in correlated systems under strong laser irradiation.
• To explore the role of quantum critical points (QCPs) and topological phases in HHG.
• To identify potential applications in ultrafast light generation and quantum phase transition studies.

Main Methods:

• Utilized the exact diagonalization method to simulate HHG in extended Hubbard and Haldane models.
• Analyzed HHG spectra near quantum critical points (QCPs) and in different topological phases.

Main Results:

• HHG is significantly enhanced near QCPs in the extended Hubbard model, especially at low frequencies.
• Systems near QCPs exhibit supersensitivity to external fields, with more optical transitions contributing to HHG.
• Even or odd harmonic components from the Haldane model can serve as spectral signatures to differentiate topological and locally ordered phases.

Conclusions:

• Materials approaching QCPs hold potential for high-efficiency harmonic generation.
• HHG can be used as a nonlinear optical probe to study quantum phase transitions and topological order.
• Findings pave the way for ultrafast light sources from correlated materials and advanced nonlinear optics studies.