Modulating carrier and sideband coupling strengths in a standing wave gate beam

TL;DR

This paper demonstrates a method to control the coupling strengths of carrier and motional sideband interactions in a trapped ion using a standing wave, enabling improved quantum control and precise ion displacement measurements.

Contribution

It introduces a standing wave technique on a microfabricated chip trap to modulate coupling strengths, avoiding complex cavity setups and enhancing quantum manipulation capabilities.

Findings

Periodic suppression of carrier and sideband transitions observed.

Precise measurement of ion displacement achieved.

Validation of trap models through ion height measurements.

Abstract

We control the relative coupling strength of carrier and first order motional sideband interactions of a trapped ion by placing it in a resonant optical standing wave. Our configuration uses the surface of a microfabricated chip trap as a mirror, avoiding technical challenges of in-vacuum optical cavities. Displacing the ion along the standing wave, we show a periodic suppression of the carrier and sideband transitions with the cycles for the two cases $180^\circ$ out of phase with each other. This technique allows for suppression of off-resonant carrier excitations when addressing the motional sidebands, with applications in quantum simulation and quantum control. Using the standing wave fringes, we measure the relative ion height as a function of applied electric field, allowing for a precise measurement of ion displacement and, combined with measured micromotion amplitudes, a validation of trap numerical models.