  Recent work has focused on exploring many-body localization (MBL) in systems
without quenched disorder: one such proposal is Stark MBL in which small
perturbations to a strong linear potential yield localization. However, as with
conventional MBL, it is challenging to experimentally distinguish between
non-interacting localization and true MBL. In this paper we show that several
existing experimental probes, designed specifically to differentiate between
these scenarios, work similarly in the Stark MBL setting. In particular we show
that a modified spin-echo response (DEER) shows clear signs of a power-law
decay for Stark MBL while quickly saturating for disorder-free Wannier-Stark
localization. Further, we observe the characteristic logarithmic-in-time
spreading of quantum mutual information in the Stark MBL regime, and an absence
of spreading in a non-interacting Stark-localized system. We also show that
there are no significant differences in several existing MBL measures for a
system consisting of softcore bosons with repulsive on-site interactions.
Lastly we discuss why curvature or small disorder are needed for an accurate
reproduction of MBL phenomenology, and how this may be illustrated in
experiment. This also connects with recent progress on Hilbert space
fragmentation in "fractonic" models with conserved dipole moment, and we
suggest this as an auspicious platform for experimental investigations of these
phenomena.
