Doping dependence versus finite-size effects in two-hole optical response

Determine whether the larger characteristic frequency scale and distinct temperature dependence of the two-hole optical conductivity arise from increased hole doping or from finite-size effects.

Background

The exact-diagonalization optical spectra for one-hole clusters show a broad low-frequency feature whose characteristic width decreases approximately linearly upon cooling. The corresponding two-hole results differ qualitatively, displaying a larger characteristic frequency scale and a different temperature dependence.

Because only small clusters are computationally accessible, the paper cannot distinguish a genuine doping dependence from artifacts associated with the finite system sizes. Resolving this ambiguity requires larger systems or complementary methods.

References

With the system sizes presently accessible, we cannot determine whether these differences reflect the higher doping or finite-size effects.

— Bad metallicity in the semi-quantum regime of the Hubbard model  (2609.19264 - Tulipman et al., 16 Sep 2026) in Section “Optical and thermodynamic signatures”