Phonon-mediated quantum gates in trapped ions coupled to an ultracold atomic gas

TL;DR

This paper investigates how an ultracold atomic gas influences phonon-mediated quantum gates in trapped ions, highlighting both decoherence effects and potential cooling benefits for quantum computing and measurements.

Contribution

It introduces a master equation approach to analyze atom-ion interactions, revealing how tuning scattering length can optimize ion cooling and gate performance.

Findings

Atomic gas causes motional decoherence reducing gate quality.

Gas can be used to cool ions and mitigate external heating.

Tuning scattering length controls ion cooling rate.

Abstract

We study the dynamics of phonon-mediated qubit-qubit interactions between trapped ions in the presence of an ultracold atomic gas. By deriving and solving a master equation to describe the combined system, we show that the presence of the atoms causes the quantum gate quality to reduce because of motional decoherence. On the other hand, we calculate that the gas may be used to keep the ion crystal cold in the presence of external heating due to electric field noise. We show that tuning the atom-ion scattering length allows one to tune the cooling rate of the ions and would make it possible to temporarily reduce the effects of the gas during a quantum gate while keeping the ions cold over long timescales. In this way, the trapped ion quantum computer may be buffer gas cooled. The system may also be used for quantum-enhanced measurements of the atom-ion interactions or properties of the atomic bath.