Spectroscopic Features of Quantum Many-Body Scar States

We studied the dynamic correlations of non-integrable systems with quantum many-body scar (QMBS) states generated by a ladder operator. The ladder operator's spectral function has an exact δ-function peak induced by the QMBS states. As a concrete example, we show that in the one-dimensional (1D) spin-1 Affleck-Kennedy-Lieb- Tasaki model, the spectral function of two-magnon excitations exhibits a characteristic bowtie shape composed of a δ-function resonance peak at momentum k=π and a continuum spectrum elsewhere. The two-magnon excitations can be observed via resonant inelastic X-ray scattering spectroscopy on quasi-1D nickelates and other spin-1 antiferromagnetic materials. Therefore, the findings of this study pave the way for detecting (approximate) QMBS states in realistic materials.