Fast mixed-species quantum logic gates for trapped-ion quantum networks

TL;DR

This paper introduces a high-speed, robust method for entangling different ion species in trapped-ion quantum computers using ultrafast laser pulses, enabling faster quantum information transfer and improved network stability.

Contribution

It develops a theoretical framework and pulse sequence design for MHz-speed mixed-species gates with realistic laser controls, advancing scalable quantum network capabilities.

Findings

Demonstrates robustness against experimental errors

Identifies ultrafast single-qubit control errors as primary limitation

Enables fast quantum information transfer between qubits and memories

Abstract

Quantum logic operations between physically distinct qubits is an essential aspect of large-scale quantum information processing. We propose an approach to high-speed mixed-species entangling operations in trapped-ion quantum computers, based on mechanical excitation of spin-dependent ion motion by ultrafast pulsed lasers. We develop the theory and machine-design of pulse sequences that realise MHz-speed `fast gates' between a range of mixed-isotope and mixed-species ion pairings with experimentally-realistic laser controls. We demonstrate the robustness of the gate mechanism against expected experimental errors, and identify errors in ultrafast single-qubit control as the primary technical limitation. The proposed mixed-species gate mechanism can be used for fast transfer of quantum information between specialized qubits and quantum memories, which we show enables the protection of matter-photon interfaces against rapid spin dephasing in optical networks of trapped-ion processors.