A Uniform Type Ia Supernova Distance Ladder with the Zwicky Transient
  Facility: Absolute Calibration Based on the Tip of the Red Giant Branch
  (TRGB) Method
  The current Cepheid-calibrated distance ladder measurement of $H_0$ is
reported to be in tension with the values inferred from the cosmic microwave
background (CMB), assuming standard model cosmology. However, the tip of the
red giant branch (TRGB) reports an estimate of $H_0$ in better agreement with
the CMB. Hence, it is critical to reduce systematic uncertainties in local
measurements to understand the origin of the Hubble tension. In this paper, we
propose a uniform distance ladder, combining SNe~Ia observed by the Zwicky
Transient Facility (ZTF) with a TRGB calibration of their absolute luminosity.
A large, volume-limited, sample of both calibrator and Hubble flow SNe Ia from
the \emph{same} survey minimizes two of the largest sources of systematics:
host-galaxy bias and non-uniform photometric calibration. We present results
from a pilot study using existing TRGB distance to the host galaxy of ZTF SN Ia
SN 2021rhu (aka ZTF21abiuvdk). Combining the ZTF calibrator with a
volume-limited sample from the first data release of ZTF Hubble flow SNe Ia, we
infer $H_0 = 76.94 \pm 6.4\, {\rm km}\,{\rm s^{-1}}\,{\rm Mpc^{-1}}$, an $8.3
\%$ measurement. The error budget is dominated by the single object calibrating
the SN Ia luminosity in this pilot study. However, the ZTF sample includes
already five other SNe Ia within $\sim$ 20 Mpc for which TRGB distances can be
obtained with HST. Finally, we present the prospects of building this distance
ladder out to 80 Mpc with JWST observations of more than one hundred SNe Ia.
