Ultrafast dynamics of quantum ionic magnetization in quantum paraelectric SrTiO₃

At cryogenic temperatures, strontium titanate (SrTiO₃) enters a quantum paraelectric state stabilized by quantum fluctuations. Resonant terahertz (THz) excitation can dynamically modify these quantum states, leading to global inversion-symmetry breaking. Here, we demonstrate circularly polarized THz-field-induced time-reversal symmetry breaking in quantum paraelectric SrTiO₃. Using second harmonic generation, which is sensitive to both spatial inversion and time-reversal symmetry breaking, we observed THz helicity-dependent fast and slow oscillatory signals. In this presentation, we will discuss the origin of these helicity-dependent oscillations by considering the quantum beating effect, implying the possibility of ultrafast optical control of ionic magnetism.