Robust and resource-efficient microwave near-field entangling $^9$Be$^+$ gate

TL;DR

This paper presents a method for making microwave entangling gates in trapped-ion quantum computers more robust against motional frequency noise by using amplitude-shaped gate drives, improving their practical reliability.

Contribution

The authors introduce and experimentally demonstrate amplitude-shaped gate drives that enhance the resilience of microwave two-qubit gates to motional frequency fluctuations without increasing energy consumption.

Findings

Amplitude modulation reduces gate infidelity to the 10^{-3} range.

Resilience to noise is demonstrated through controlled noise injection.

Method maintains low energy per gate while improving robustness.

Abstract

Microwave trapped-ion quantum logic gates avoid spontaneous emission as a fundamental source of decoherence. However, microwave two-qubit gates are still slower than laser-induced gates and hence more sensitive to fluctuations and noise of the motional mode frequency. We propose and implement amplitude-shaped gate drives to obtain resilience to such frequency changes without increasing the pulse energy per gate operation. We demonstrate the resilience by noise injection during a two-qubit entangling gate with $^9$Be$^+$ ion qubits. In absence of injected noise, amplitude modulation gives an operation infidelity in the $10^{-3}$ range.