Exact and asymptotic dissipative spectral form factor for elliptic Ginibre unitary ensemble

Abstract: The dissipative spectral form factor (DSFF) has recently emerged as a diagnostic tool for assessing non-integrability or chaos in non-Hermitian systems. It extends the concept of the spectral form factor (SFF), a widely used measure for similar investigations in Hermitian systems. In this study, we concentrate on the elliptic Ginibre unitary ensemble (eGinUE), which interpolates between the non-Hermitian limit of Ginibre unitary ensemble (GinUE) and the Hermitian limit of Gaussian unitary ensemble (GUE) by varying a symmetry parameter. We derive exact finite-dimension expression and large-dimension approximation for the DSFF of eGinUE. A key finding of this work is a compelling ``scaling relationship" between the DSFF of eGinUE and that of the GUE or GinUE. This scaling relationship also reveals a previously unobserved connection between the DSFF of GinUE and the SFF of GUE. The DSFF for eGinUE displays a \emph{dip-ramp-plateau} structure in the GinUE and GUE limits, as well as in the crossover region, with differences in time scales that are well-explained by the aforementioned scaling relationship. Additionally, depending on the symmetry regime within the crossover, we provide various estimates for the Thouless time ($T_\mathrm{Th}$) and Heisenberg time ($T_\mathrm{H}$), which correspond to the dip-ramp and ramp-plateau transitions, respectively. Our analytical results are compared with Monte Carlo simulations of the eGinUE random matrix model, showing excellent agreement.