Southwest Quantum Information and Technology

Laser-free trapped-ion entangling gates

Presenting Author: Raghavendra Srinivas, National Institute of Standards and Technology, Boulder
Contributing Author(s): Shaun Burd, Robert Sutherland, Hannah Knaack, Dietrich Leibfried, David Wineland, Andrew Wilson, David Allcock, Daniel Slichter

Trapped-ion entangling gates are usually performed using laser-induced coupling of the ions’ internal spin states to their motion. Laser-free methods, which eliminate photon scattering errors and offer benefits for scalability have been proposed and demonstrated using static magnetic field gradients or magnetic field gradients oscillating at GHz frequencies [1-4]. We demonstrate a recently proposed method for trapped-ion entangling gates [5] implemented using an oscillating magnetic field gradient at radio frequency in addition to two microwave magnetic fields symmetrically detuned about the qubit frequency. This implementation offers important technical advantages over other laser-free techniques, while also enabling laser-free entangling gates with reduced sensitivity to qubit frequency errors. These experiments are performed in a surface-electrode trap that incorporates current-carrying electrodes to generate the microwave fields and the oscillating magnetic field gradient. Currently, we achieve a Bell-state fidelity of 0.996(2) with ground-state-cooled ions and 0.991(3) for ions cooled to the Doppler limit (nbar=2). [1] Mintert and Wunderlich PRL 87, 257904 (2001) [2] Weidt et al. PRL 117, 220501 (2016) [3] Ospelkaus et al. Nature 476, 181 (2011) [4] Harty et al. PRL 117, 140501 (2016) [5] Sutherland et al. NJP 21, 033033 (2019)

(Session 13 : Monday from 3:30pm - 4:00pm)