Microwave Near-Field Quantum Control of Trapped Ions

TL;DR

This paper details the setup, calibration, and characterization of microwave near-field control for trapped 25Mg+ ions, enabling two-ion entanglement, and discusses current limitations of microwave-driven entangling gates.

Contribution

It provides detailed experimental procedures, trap design insights, and a novel method for detecting micromotion, advancing microwave quantum control of trapped ions.

Findings

Comparison of experimental near-fields with simulations

Method for detecting micromotion using magnetic-field gradients

Discussion of limitations in microwave entangling gates

Abstract

Microwave near-field quantum control of spin and motional degrees of freedom of 25Mg+ ions can be used to generate two-ion entanglement, as recently demonstrated in Ospelkaus et al. [Nature 476, 181 (2011)]. Here, we describe additional details of the setup and calibration procedures for these experiments. We discuss the design and characteristics of the surface-electrode trap and the microwave system, and compare experimental measurements of the microwave near-fields with numerical simulations. Additionally, we present a method that utilizes oscillating magnetic-field gradients to detect micromotion induced by the ponderomotive radio-frequency potential in linear traps. Finally, we discuss the present limitations of microwave-driven two-ion entangling gates in our system.