Sub-microsecond entangling gate between trapped ions via Rydberg interaction

TL;DR

This paper demonstrates a sub-microsecond entangling gate between trapped Rydberg ions using strong dipolar interactions, achieving high fidelity and paving the way for faster, scalable quantum computing and simulation.

Contribution

It introduces a 700 ns two-ion entangling gate leveraging Rydberg interactions in trapped ions, combining strengths of ion and Rydberg systems for scalable quantum operations.

Findings

Achieved a 700 ns entangling gate with 78% fidelity.

Predicted total error below 0.2% with realistic parameters.

Residual motional coupling causes negligible error (~10^-4) in large ion crystals.

Abstract

Generating quantum entanglement in large systems on time scales much shorter than the coherence time is key to powerful quantum simulation and computation. Trapped ions are among the most accurately controlled and best isolated quantum systems with low-error entanglement gates operated via the vibrational motion of a few-ion crystal within tens of microseconds. To exceed the level of complexity tractable by classical computers the main challenge is to realise fast entanglement operations in large ion crystals. The strong dipole-dipole interactions in polar molecule and Rydberg atom systems allow much faster entangling gates, yet stable state-independent confinement comparable with trapped ions needs to be demonstrated in these systems. Here, we combine the benefits of these approaches: we report a $700\,\mathrm{ns}$ two-ion entangling gate which utilises the strong dipolar interaction between trapped Rydberg ions and produce a Bell state with $78\%$ fidelity. The sources of gate error are identified and a total error below $0.2\%$ is predicted for experimentally-achievable parameters. Furthermore, we predict that residual coupling to motional modes contributes $\sim 10^{-4}$ gate error in a large ion crystal of 100 ions. This provides a new avenue to significantly speed up and scale up trapped ion quantum computers and simulators.