A low-volume cold-atom microwave clock with an additively manufactured cavity

We present the performance of a compact microwave interrogated atomic clock based on laser cooled $^{87}$$\rm{Rb}$ atoms. The clock utilizes a micro-fabricated grating magneto-optical trap (gMOT) to cool and trap atoms, and an additively manufactured microwave cavity for microwave interrogation. We demonstrate a signal-to-noise ratio (SNR) of $370$ at a 1 Hz bandwidth and mid-term instability of $6.7\times10^{-14}$ at an averaging time of $τ=3 \times 10^{4}$ s. In addition, a low cost mu-metal foil has been implemented on the vacuum chamber to reduce the quadratic Zeeman shift which was previously limiting stability beyond $τ= 10$ s.