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System scalability is fundamental for large-scale quantum computers (QCs) and is being pursued over a variety of hardware platforms. For QCs based on trapped ions, architectures such as the quantum charge-coupled device (QCCD) are used to scale the number of qubits on a single device. However, the number of ions that can be hosted on a single quantum computing module is limited by the size of the chip being used. Therefore, a modular approach is of critical importance and requires quantum connections between individual modules. Here, we present the demonstration of a quantum matter-link in which ion qubits are transferred between adjacent QC modules. Ion transport between adjacent modules is realised at a rate of 2424 s−1 and with an infidelity associated with ion loss during transport below 7 × 10−8. Furthermore, we show that the link does not measurably impact the phase coherence of the qubit. The quantum matter-link constitutes a practical mechanism for the interconnection of QCCD devices. Our work will facilitate the implementation of modular QCs capable of fault-tolerant utility-scale quantum computation.

Microfabricated ion-trap devices offer a promising pathway towards scalable quantum computing. Research efforts have begun to focus on the engineering challenges associated with developing large-scale ion-trap arrays and networks. However, increasing the size of the array and integrating on-chip electronics can drastically increase the power dissipation within the ion-trap chips. This leads to an increase in the operating temperature of the ion-trap and limits the device performance. Therefore, effective thermal management is an essential consideration for any large-scale architecture. Presented here is the development of a modular cooling system designed for use with multiple ion-trapping experiments simultaneously. The system includes an extensible cryostat that permits scaling of the cooling power to meet the demands of a large network. Following experimental testing on two independent ion-trap experiments, the cooling system is expected to deliver a net cooling power of 111 W at ∼70 K to up to four experiments. The cooling system is a step towards meeting the practical challenges of operating large-scale quantum computers with many qubits.

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We have demonstrated a capacitively-coupled, RF microplasma inside the 3D electrode structure of an ion microtrap device. For this work, devices with an inter-electrode distance of 340 µm were used. The microplasmas were operated at Ω RF /2π = 23 MHz, in both He and He:N 2 gas mixtures, over a range of RF amplitudes (140 V to 220 V) and pressures (250 mbar to 910 mbar). Spectroscopic analysis of the He I 667 nm and Hα 656 nm emission lines yielded the gas temperature and electron density, which enabled calculation of the mean ion bombardment energy. For the range of operating parameters studied, we calculated mean He + energies to be between 0.3 eV and 4.1 eV. While these energies are less than the threshold for He sputtering of hydrocarbon adsorbates on Au, we calculate that the high energy tail of the distribution should remove adsorbate monolayers in as little as 1 minute of processing. We also calculate that the distribution is insufficiently energetic to have any significant effect on the Au electrode surface within that duration. Our results suggest that the microplasma technique is suited to in situ selective removal of surface adsorbates from ion microtrap electrodes.