Implementing segmented ion trap designs for quantum computing

Thesis

With all the key elements of quantum computing in ion traps demonstrated by the research community, the focus is now placed on building more sophisticated traps with larger numbers of ions to allow practical scale information processing. One promising avenue is to store ions in and shuttle them between many independent traps which serve as potential interaction sites.

The core of the work described in this thesis is the experimental evaluation of a microfabricated segmented ion trap, built by Sandia National Laboratories ("Sandia trap"). These experiments required construction of a wholly new optical setup including laser and detection systems, a vacuum system and control electronics. Among our experimental achievements were: successful loading of single and pairs of ions in the microscale trap, measurement of ion storage lifetime, measurement of the motional heating rate with a time-resolved Doppler-cooling method — which showed above than average heating, and implemented a single-ion shuttling method — which reliably transferred the ion through a distance of 360 μm (two DC electrode widths away) and back. These results have been used to improve the next version of the Sandia trap design.

We also used computer modelling to study several aspects of ion traps: a mesoscopic ion trap designed for fast ion separation, simulated ion loading to quantify requirements for successful trapping in small and shallow traps, and analyzed a precise shuttling method — where the time dependence of the trapping potential is engineered such that there is minimal motional heating.

The results show that ion trap arrays at the 100 μm distance scale are feasible and suggests that such multiple trap designs merit further study.

Authors: Imreh, G

• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Keywords: Simulation; Laser; Calcium; Matlab; Ion trap
• Subjects: Quantum computer; Atomic physics; Quantum computing