Speaker
Description
Matter-wave interferometers (MWIs) provide a uniquely quantum route to dark matter (DM) detection: DM can be detected through phases and decoherence between spatially separated wavepackets, even when energy deposition is negligible and no recoil is resolvable. I will describe an open effective field theory for MWIs, formulated using the Schwinger-Keldysh formalism, that systematically computes these observables and clarifies the relation between them. A key outcome is a structural asymmetry between phase and decoherence: for elastic spin-independent DM scattering, decoherence can receive Bose enhancement or Pauli blocking factors, whereas the phase remains at most linear in the DM occupation number. Using these results, I will then turn to novel ideas for probing light DM with matter-wave interferometry, including trapped-ion platforms and correlated pairs of mesoscopic interferometers, which may open sensitivity to unexplored regions near the wave--particle boundary.