Manipulation of Ultra-Cold Atoms Using Radio-Frequency and Microwave Radiation

马红玉 Ma Hongyu, 韩一平 Han Yiping

Simon Bernon, H. Hattermann, Daniel Bothner +8 more

Justin M. Winkler

This thesis describes the design, construction, and testing of a radio frequency signal source for generating rapidly changing frequencies in a repeatable and phase continuous manner. The radio frequency (RF) signal is generated by a Direct Digital Synthesizer (DDS) which is controlled by a triggerable microprocessor unit which is itself remotely programmed through an Ethernet connection. Waveforms generated by the RF source can be used for direct RF evaporation or RF manipulation of magnetic trapping potentials for ultra-cold atoms on an atom chip. The ultimate objective of the project is to mix the RF signal with higher frequency carrier waves to generate microwaves for the manipulation of hyperfine states of ultra-cold atoms of potassium and rubidium.

D. Ciampini, E. Courtade, Carlo Sias +5 more

Bernd Meyer-Hoppe, Maximilian Baron, Christophe Cassens +4 more

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 ± 25 MHz for hyperfine transitions in 87Rb. The presented microwave source combines two commercially available frequency synthesizers: an ultra-low-noise oscillator at 7 GHz and a direct digital synthesizer for radio frequencies. We demonstrate a low integrated phase noise of 480 µrad in the range of 10 Hz to 100 kHz and fast updates of frequency, amplitude, and phase in sub-µs 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.