Two-qubit gates in a trapped-ion quantum computer by engineering motional modes

TL;DR

This paper proposes a method to simplify two-qubit gate implementation in trapped-ion quantum computers by engineering motional modes, reducing control complexity and enabling more scalable quantum operations.

Contribution

It introduces a novel approach to remove pulse-modulation complexity through motional mode engineering in ion chains, adaptable to existing and future quantum systems.

Findings

Mode engineering feasible for three-ion chains

Gate implementation without complex pulse modulation

Potential for scalable quantum computing hardware

Abstract

A global race towards developing a gate-based, universal quantum computer that one day promises to unlock the never before seen computational power has begun and the biggest challenge in achieving this goal arguably is the quality implementation of a two-qubit gate. In a trapped-ion quantum computer, one of the leading quantum computational platforms, a two-qubit gate is typically implemented by modulating the individual addressing beams that illuminate the two target ions, which, together with others, form a linear chain. The required modulation, expectedly so, becomes increasingly more complex, especially as the quantum computer becomes larger and runs faster, complicating the control hardware design. Here, we develop a simple method to essentially remove the pulse-modulation complexity at the cost of engineering the normal modes of the ion chain. We demonstrate that the required mode engineering is possible for a three ion chain, even with a trapped-ion quantum computational system built and optimized for a completely different mode of operations. This indicates that a system, if manufactured to target specifically for the mode-engineering based two-qubit gates, would readily be able to implement the gates without significant additional effort.