Determination of quantum defect for the Rydberg P series of Ca II

Abstract

We present an experimental investigation of the Rydberg 23 P 1/2 state of single, laser-cooled 40 Ca + ions in a radiofrequency ion trap. Using micromotion sideband spectroscopy on a narrow quadrupole transition, the oscillating electric field at the ion position was precisely characterised, and the modulation of the Ryd-berg transition due to this field was minimised. From a correlated fit to this P line and previously measured P and F level energies of Ca II, we have determined the ionization energy of 95 751.916(32) cm −1 , in agreement with the accepted value, and the quantum defect for the n P 1/2 states.

Trapped Rydberg ions: A new platform for quantum information processing

“…2(a)). This setup was used to observe 3D 3/2 → 52F, 3D 3/2 → 53F and 3D 5/2 → 66F [4], 3D 5/2 → 22F [7] and 3D 3/2 → 23P 1/2 [8] transitions (Fig. 2(a)).…”

“…In this method, ions are transported from such a loading zone into the experimental zone at which the laser pulses for qubit control are applied. Such a "remote loading" has been applied in experiments with Rydberg Ca + ions in the Mainz blade trap with segmented electrodes [8], see Fig. 3.…”

“…Rydberg state spectroscopy in combination with Rydberg-series extrapolation provides the most precise method for determining the ionization threshold I ++ [154,155]. For trapped Rydberg ions, S and D Rydberg series of 88 Sr + ions [95] and S, P, D and F series of 40 Ca + ions [4,7,8,156] were used to determine the quantum defects and their ionization energies. The most precise measurement has been done for the S states of a single Ca + ion using the two-step Rydberg excitation scheme (Sec.…”

“…One decade after the first theoretical proposal for exploring Rydberg ions as a new platform for such applications [3], experimental work has succeeded in demonstrating major milestones. These include the first excitation of trapped Ca + ions to Rydberg states in a radiofrequency (RF) ion trap [4], the observation and characterisation of the trapping fields' effects on Rydberg ions and spectroscopy of Rydberg transitions for Sr + [5,6] and Ca + ions [7,8]. Further progress has been achieved by coherent manipulation of a Rydberg state of single trapped Sr + ion [6,9].…”

Long-Range Multibody Interactions and Three-Body Antiblockade in a Trapped Rydberg Ion Chain

“…The possibility to engineer phonon-mediated two-body interactions, which can be tuned via laser fields and trapping parameters, combined with single-ion control and high fidelity state preparation, makes them a powerful platform for quantum simulation and information processing [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. A further enhancement of this setup can be achieved in trapped Rydberg ions, where each ion can be individually excited to a highlying Rydberg level [15][16][17][18][19][20][21][22][23]. The strong dipole-dipole interactions and the interplay between electronic and vibrational degrees of freedom characterizing this system can be exploited to simulate equilibrium and non-equilibrium quantum manybody spin models [24][25][26], to devise non-classical motional states [27], and for quantum information processing beyond the scalability limitations of conventional ion settings [28][29][30].…”