Operational and data analysis improvements for a quantum-enhanced search for dark matter axions

HAYSTAC is the first axion dark matter haloscope to circumvent the quantum limit using vacuum squeezing technology. The experiment utilizes the resonant conversion of axions to microwave photons in a high Q cavity in the presence of a strong magnetic field, and implements a squeezed-state receiver system to enhance the search rate. The Phase 2 operation observes no signature of dark matter axions over the combined 16.96-17.12 and 17.14-17.28 $\mu eV/c^2$ mass range, and achieves $90\%$ exclusion for axion-photon couplings above $g_{\gamma}$ = 1.38 $ \times g_{\gamma}^{KSVZ}$. In this talk, I will describe upgrades made to operational procedures and data analysis programs for the Phase 2 experiment, including characterizations of microwave cavity response and squeezed state receiver circuit properties, as well as updates and run-time improvements to the data analysis program.