Periodic Reporting for period 1 - RydIons (Coherent manipulation of cold trapped ions in Rydberg states)
Reporting period: 2018-04-01 to 2020-03-31
(1) The project started by Rydberg excitation of trapped calcium ions in a linear segmented radiofrequency (RF) ion trap. Rydberg states of calcium ions were excited from metastable D states in a single-step excitation using a VUV laser system at 123 nm. This nontrivial radiation source was used for studying a certain Rydberg P state, see figure (1).
(2) Over the course of the project, we have developed another experimental setup in which Rydberg excitation was carried out using two high-power commercial UV laser systems. This setup became fully operational as an essential progress in line with the proposed research.
(3) The two-step Rydberg excitation scheme was used for an elaborate investigation of nS and nD Rydberg series. These results were used to precisely determine the value for the second ionisation energy of calcium ions with significantly improved uncertainties, see figure (2).
(4) We performed a theoretical study for implementing fast entangling operations using electric pulses act on trapped Rydberg ions. In this scheme, a fast electric pulse generates a state-dependent force and leads to accumulation of a phase which can be precisely controlled in our experiment. These calculations have established a powerful technique to realise fast quantum gates using trapped Rydberg ions with applications in quantum information processing.
(1) Further measurements and technical improvements will be performed using the newly built setup to enable coherent manipulation of Rydberg states. The setup has been also prepared for microwave spectroscopy, and microwave-dressed Rydberg states will be characterised.
(2) This project shows great potential for investigating many-body quantum systems. One interesting direction is to use Rydberg excitation for generating the state-dependent force that can lead to structural phase transitions.
(3) The experimental work is expected to reach the stage that can be used for realising a Rydberg quantum simulator in which dipolar interactions between ions can be used to mimic energy exchange in linear chains.
(4) The theoretical calculation performed has certainly open doors for implementing fast quantum gates. We are determined to take advantage of our advance setup to realise such gates and to improve the record by optimal control of our experimental parameters.