High-fidelity trapped-ion qubit operations with scalable photonic modulators

TL;DR

This paper presents the design, fabrication, and testing of a monolithically integrated optical modulator for trapped-ion qubits, achieving high-fidelity single-qubit operations exceeding 99.7% fidelity, addressing scalability challenges in quantum computing.

Contribution

It introduces a scalable, monolithically integrated photonic modulator for trapped-ion systems, improving integration and performance for quantum computing applications.

Findings

Achieved single-qubit gate fidelities over 99.7%.

Demonstrated monolithic integration of optical modulators with ion traps.

Enhanced characterization of gate errors using quantum tomography.

Abstract

Experiments with trapped ions and neutral atoms typically employ optical modulators in order to control the phase, frequency, and amplitude of light directed to individual atoms. These elements are expensive, bulky, consume substantial power, and often rely on free-space I/O channels, all of which pose scaling challenges. To support many-ion systems like trapped-ion quantum computers or miniaturized deployable devices like clocks and sensors, these elements must ultimately be microfabricated, ideally monolithically with the trap to avoid losses associated with optical coupling between physically separate components. In this work we design, fabricate, and test an optical modulator capable of monolithic integration with a surface-electrode ion trap. These devices consist of piezo-optomechanical photonic integrated circuits configured as multi-stage Mach-Zehnder modulators that are used to control the intensity of light delivered to a single trapped ion on a separate chip. We use quantum tomography employing hundreds of multi-gate sequences to enhance the sensitivity of the fidelity to the types and magnitudes of gate errors relevant to quantum computing and better characterize the performance of the modulators, ultimately measuring single qubit gate fidelities that exceed 99.7%.