Trapped ion entanglement gates made robust to Rabi frequency fluctuations via motional squeezing

Trapped ion qubits are a leading quantum computing platform. As part of an effort to scale-up the quantum register while maintaining high-fidelity operations, there has been a recent focus on generation of robust quantum operations, specifically robust entanglement gates.

Recently our group developed and demonstrated schemes for robust entanglement gates using polychromatic global addressing of the ion chain [1]. Many aspects of these gates have been made robust using this method, as well as other methods, yielding gates which are robust to: unwanted couplings, timing errors, frequency drifts, heating, among other examples. However, these methods cannot mitigate drifts in the gate Rabi frequency, a prevalent error source in trapped ions due to noise at the drive source, or beam-pointing drifts.

By driving high-order motional sidebands of the ions chain, as described by Sameti et al. [2], we use motional squeezing effects in order to devise a gate which is indeed robust to drifts in its Rabi frequency. We combine this form of robustness with the established properties above generating a resilient entanglement gate scheme.

References:

[1] Shapira et al. PRL (2018). Shapira e al. PRA (2020). Manovitz et al. arXiv preprint (2021).

[2] M. Sameti et al. PRA (2021)