Abstract
We describe and benchmark a new quantum charge-coupled device (QCCD) trapped-ion quantum computer based on a linear trap with periodic boundary conditions, which resembles a race track. The new system successfully incorporates several technologies crucial to future scalability—including electrode broadcasting, multilayer rf routing, and magneto-optical trap (MOT) loading—while maintaining, and in some cases exceeding, the gate fidelities of previous QCCD systems. The system is initially operated with 32 qubits, but future upgrades will allow for more. We benchmark the performance of primitive operations, including an average state preparation and measurement error of , an average single-qubit gate infidelity of , and an average two-qubit gate infidelity of . The system-level performance of the quantum processor is assessed with mirror benchmarking, linear cross-entropy benchmarking, a quantum volume measurement of , and the creation of 32-qubit entanglement in a GHZ state. We also tested application benchmarks, including Hamiltonian simulation, QAOA, error correction on a repetition code, and dynamics simulations using qubit reuse. We also discuss future upgrades to the new system aimed at adding more qubits and capabilities.
17 More- Received 17 May 2023
- Revised 15 August 2023
- Accepted 28 September 2023
DOI:https://doi.org/10.1103/PhysRevX.13.041052
Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International license. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.
Published by the American Physical Society
Physics Subject Headings (PhySH)
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Scaling Up a Trapped-Ion Quantum Computer
Published 18 December 2023
Major technical improvements to a quantum computer based on trapped ions could bring a large-scale version closer to reality.
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Popular Summary
Quantum computing is a fast-moving field, with researchers making tremendous progress in the last few years in building hardware. There are many proposed architectures for large-scale quantum computing, each with their own plans for scaling to large systems. Here, we present our progress in scaling a trapped-ion quantum computer to a larger number of qubits in a more complex trap, while maintaining similar or better performance compared to our earlier devices. The new system features several upgrades that will enable us to realistically scale to larger numbers of qubits.
We benchmarked the performance of our system at three progressively higher levels. First, we measured the errors of individual gates and other primitive operations that are the building blocks of our quantum computer. Then, we looked at more complex circuits, where errors can accumulate in nontrivial ways. From these measurements, we can extract effective gate fidelities that are consistent with the individual gate benchmarking. Finally, we ran example algorithms that closely match potential near-term use cases. Our results suggest that increasing circuit depth or time to a nontrivial degree is viable given our gate fidelities.
Our new system is currently operating with 32 qubits, but we plan on continuing to upgrade to more qubits and better performance. Doing so will allow us to enter the quantum advantage regime, where quantum computers will begin to perform computations that cannot be done in a reasonable amount of time on classical computers.