Single-ion addressing via trap potential modulation in global optical fields

TL;DR

This paper demonstrates a method for individually addressing ion qubits in a two-ion crystal using trap potential modulation within a global optical field, enabling universal control with a single laser beam.

Contribution

It introduces a novel approach to ion qubit control by leveraging axial potential modulation for individual addressing in a global laser field.

Findings

Successful individual addressing of $^{40}$Ca$^+$ ions using trap potential modulation.

Characterization of gate performance via randomized benchmarking.

Identification of primary error sources and comparison with single-ion experiments.

Abstract

To date, individual addressing of ion qubits has relied primarily on local Rabi or transition frequency differences between ions created via electromagnetic field spatial gradients or via ion transport operations. Alternatively, it is possible to synthesize arbitrary local one-qubit gates by leveraging local phase differences in a global driving field. Here we report individual addressing of $^{40}$Ca$^+$ ions in a two-ion crystal using axial potential modulation in a global gate laser field. We characterize the resulting gate performance via one-qubit randomized benchmarking, applying different random sequences to each co-trapped ion. We identify the primary error sources and compare the results with single-ion experiments to better understand our experimental limitations. These experiments form a foundation for the universal control of two ions, confined in the same potential well, with a single gate laser beam.