Step 11. Sensitivity & feasibility (bounds-first: what you can really claim)

Plain English: The paper is explicit: all numbers you quote are bounds, not promised detections. There are two kinds you should publish:

  1. Visibility bounds: if you report a Markovian (white-at-low-f) bound on \(S_{\Phi}(0)\), you must also report the filter-weighted bound using your actual \(|F(\Omega)|^{2}\) so that non-white noise is handled honestly:

\[ -\ln V=\frac{\omega^{2}}{2}\!\int_{0}^{\infty}\frac{d\Omega}{2\pi}\,S_{\Phi}(\Omega)\,|F(\Omega)|^{2}. \]

Include both in results.

  1. Flux→drift fits: when fitting \(\dot y(t)=-\lambda L(t)+\dots\) in the lab, publish both the statistical variance and the total variance including calibration and model systematics:

\[ \mathrm{Var}_{\text{tot}}(\hat\lambda)\approx \mathrm{Var}_{\text{stat}}(\hat\lambda)+\hat\lambda^{2}\!\left(\sigma_r^2+\sigma_L^2\right)+\Delta_S, \]

with the linearized sensitivity \(\delta\hat\lambda/\hat\lambda\simeq -\epsilon_r-\epsilon_L+O(\epsilon_S)\). In practice, the calibration on distance \(r\) and power \(L\) dominates.

Noise budget you must list (visibility channel): three gravitational pieces plus standard lab systematics: • Newtonian gravity-gradient (seismic/air density), typically dominant < 1 Hz; • Stress-tensor (shot/thermal) from radiative fluxes; • Vacuum TT modes mapped through the constraint kernel (tiny in lab band). Always provide a source-off baseline and subtract it. (The paper even gives typical magnitudes: around 1 Hz, \(S_{\Phi}\sim10^{-32}\,\text{s}\); around 1 kHz, \(S_{\Phi}^{\mathrm{vac}}\sim10^{-45}\,\text{s}\).)

Framing in the paper (why “bounds-first”): it explicitly states that the sensitivity numbers assume ideal filters with measured \(S_y(f)\); real measurements are limited by current tech, and no detection timelines are claimed.


Glossary (for this step)

Symbol Name Meaning (units) Typical value/example Metaphor
\(S_{\Phi}(\Omega)\) Lapse PSD One-sided spectrum of \(\delta\Phi\) (s) Report Markovian and filter-weighted bounds “Noise color of time”
( F() ^{2}) Filter kernel From your sequence \(f(t)\) (s²) sinc² for rectangular windows “Sieve for noise tones”
\(\hat\lambda\) Flux–drift gain Fit slope in \(\dot y=-\lambda L\) (s²·kg\(^{-1}\)·m\(^{-1}\)) Publish \(\mathrm{Var}_{\text{stat}}\) and \(\mathrm{Var}_{\text{tot}}\) “Gear ratio” from flux to drift
\(\sigma_r,\sigma_L\) Calibrations Fractional errors in \(r\), \(L\) (–) Often dominate lab totals “Ruler & wattmeter wiggle”
\(S_{\Phi}^{\text{Newt}}\) Gravity-gradient From density/seismic noise (s) \(\sim10^{-32}\,\text{s}\) @ 1 Hz “Breathing of the ground”

Ready for Step 12 — Registered workflow & publishing checklist (exact items to pre-register and what every result must include).