Exceptional piece on tidal gravitational phase shifts in quantum interferometry. The gap between COW effects at 100 radians and tidal contributions around 10^-21 radians really underscores how the semiclassical framework is pushign into territory where even future tech might struggle. I worked with some cold atom setups a while back, and maintaining coherence over meter scales was already brutal; the kilometer-scale space interferometer idea sounds wild but getting phase stability there seems almost impossible. What makes the frame-dragging signture especially intriguing is that odd-parity dependence on slit separation.