The generation and manipulation of ultracold atomic ensembles in the quantum regime require the application of dynamically controllable microwave fields with ultra-low noise performance. Here, we present a low-phase-noise microwave source with two independently controllable output paths. Both paths generate frequencies in the range of $6.835,$GHz $pm$ $25,$MHz for hyperfine transitions in $^{87}$Rb. The presented microwave source combines two commercially available frequency synthesizers: an ultra-low-noise oscillator at $7,$GHz and a direct digital synthesizer for radiofrequencies. We demonstrate a low integrated phase noise of $580,mu$rad in the range of $10,$Hz to $100,$kHz and fast updates of frequency, amplitude and phase in sub-$mu$s time scales. The highly dynamic control enables the generation of shaped pulse forms and the deployment of composite pulses to suppress the influence of various noise sources.
Download