Signature of PT -symmetric non-Hermitian superconductivity in angle-resolved photoelectron fluctuation spectroscopy

Abstract

We show theoretically that the measurement of a $\mathcal{PT}$-symmetric non-Hermitian superconductor by angle-resolved photoelectron fluctuation spectroscopy (ARPFS) provides a decisive signature. In fact, the signal is negative in a single-band case in contrast to the ARPFS signal of Hermitian superconductors. We suggest that the negative fluctuations can be explained by a remarkable pairing phenomenon: If the interaction between electrons in this $\mathcal{PT}$-symmetric non-Hermitian superconductor is attractive then the interaction between holes (i.e. missing electrons) is repulsive and vice versa. This difference in the sign of the interactions gives rise to negative cross correlations. Here, we propose how such electron-electron interaction can occur due to spatiotemporal modulation of the material. We also discuss the observability of this signature in multi-band systems.