Continuous Guided Strontium Beam with High Phase-Space Density

A continuous guided atomic beam of ⁸⁸Sr with a phase-space density exceeding 10^-4 in the moving frame and a flux of 3×10⁷ at. s^-1 is demonstrated. This phase-space density is around 3 orders of magnitude higher than previously reported for steady-state atomic beams. We detail the architecture necessary to produce this ultracold-atom source and characterize its output after propagation for approximately 4cm. With radial temperatures of less than 1μK and a velocity of 8.4cm s^-1, this source is ideal for a range of applications. For example, it could be used to replenish the gain medium of an active optical superradiant clock or be used to overcome the Dick effect, which can limit the performance of pulsed-mode atom interferometers, atomic clocks, and ultracold-atom-based sensors in general. Finally, this result represents a significant step toward the development of a steady-state atom laser.