  Most matter-wave interferometry (MWI) schemes for quantum sensing are so far
evaluated in ideal situations without noises. In this work, we provide
assessments of generic multiqubit MWI schemes under Markovian dephasing noises.
We find that for certain classes of the MWI schemes with scale factors that are
nonlinearly dependent on the interrogation time, the optimal precision of
maximally entangled probes \emph{decreases} with increasing the particle number
$N$, for both independent and collective dephasing situations. This result
challenges the conventional wisdom found in dephasing Ramsey-type
interferometers. We initiate the analyses by investigating the optimal
precision of multiqubit Sagnac atom interferometry for rotation sensing. And we
show that due to the competition between the unconventional interrogation-time
quadratic phase accumulation and the exponential dephasing processes, the
Greenberger-Horne-Zeilinger (GHZ) state, which is the optimal input state in
noiseless scenarios, leads to vanishing quantum Fisher information in the
large-$N$ regime. Then our assessments are further extended to generic MWI
schemes for quantum sensing with entangled states and under decoherence.
Finally, a quantum error-correction logical GHZ state is tentatively analyzed,
which could have the potential to recover the Heisenberg scaling and improve
the sensitivity.
