The trapped-ion QCCD (quantum charge-coupled device) architecture proposal lays out a blueprint for a universal quantum computer. The design begins with electrodes patterned on a two-dimensional surface configured to trap multiple arrays of ions (or ion crystals). Communication within the ion crystal network allows for the machine to be scaled while keeping the number of ions in each crystal to a small number, thereby preserving the low error rates demonstrated in trapped-ion experiments. By proposing to communicate quantum information by moving the ions through space to interact with other distant ions, the architecture creates a quantum computer endowed with full-connectivity. However, engineering this fully-connected computer introduces a host of difficulties that have precluded the architecture from being fully realized in the twenty years since its proposal. Using a Honeywell cryogenic surface trap, we report on the integration of all necessary ingredients of the QCCD architecture into a programmable trapped-ion quantum computer. Using four and six qubit circuits, the system level performance of the processor is quantified by the fidelity of a teleported CNOT gate utilizing mid-circuit measurement and a quantum volume measurement of $2^6=64$ . By demonstrating that the low error rates achievable in small ion crystals can be successfully integrated with a scalable trap design, parallel optical delivery, and fast ion transport, the QCCD architecture is shown to be a viable path toward large quantum computers. Atomic ions provide perfectly identical, high-fidelity qubits. Our work shows that the QCCD architecture built around these qubits will provide high performance quantum computers, likely enabling important near-term demonstrations such as quantum error correction and quantum advantage.The trapped-ion QCCD (quantum charge-coupled device) architecture proposal lays out a blueprint for a universal quantum computer. The design begins with electrodes patterned on a two-dimensional surface configured to trap multiple arrays of ions (or ion crystals). Communication within the ion crystal network allows for the machine to be scaled while keeping the number of ions in each crystal to a small number, thereby preserving the low error rates demonstrated in trapped-ion experiments. By proposing to communicate quantum information by moving the ions through space to interact with other distant ions, the architecture creates a quantum computer endowed with full-connectivity. However, engineering this fully-connected computer introduces a host of difficulties that have precluded the architecture from being fully realized in the twenty years since its proposal. Using a Honeywell cryogenic surface trap, we report on the integration of all necessary ingredients of the QCCD architecture into a programmable trapped-ion quantum computer. Using four and six qubit circuits, the system level performance of the processor is quantified by the fidelity of a teleported CNOT gate utilizing mid-circuit measurement and a quantum volume measurement of $2^6=64$. By demonstrating that the low error rates achievable in small ion crystals can be successfully integrated with a scalable trap design, parallel optical delivery, and fast ion transport, the QCCD architecture is shown to be a viable path toward large quantum computers. Atomic ions provide perfectly identical, high-fidelity qubits. Our work shows that the QCCD architecture built around these qubits will provide high performance quantum computers, likely enabling important near-term demonstrations such as quantum error correction and quantum advantage.

Mar 3, 202043 citations

A Race-Track Trapped-Ion Quantum Processor

Steven A. Moses, Charles H. Baldwin, M. S. Allman +93 more

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 1.6ð1Þ × 10 -3 , an average single-qubit gate infidelity of 2.5ð3Þ × 10 -5 , and an average two-qubit gate infidelity of 1.84ð5Þ × 10 -3 .The systemlevel performance of the quantum processor is assessed with mirror benchmarking, linear cross-entropy benchmarking, a quantum volume measurement of QV ¼ 2 16 , 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.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 1.6ð1Þ × 10 -3 , an average single-qubit gate infidelity of 2.5ð3Þ × 10 -5 , and an average two-qubit gate infidelity of 1.84ð5Þ × 10 -3 .The systemlevel performance of the quantum processor is assessed with mirror benchmarking, linear cross-entropy benchmarking, a quantum volume measurement of QV ¼ 2 16 , 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.

arXiv:2305.03828Physical Review XDec 18, 2023391 citations

2^6=64

. By demonstrating that the low error rates achievable in small ion crystals can be successfully integrated with a scalable trap design, parallel optical delivery, and fast ion transport, the QCCD architecture is shown to be a viable path toward large quantum computers. Atomic ions provide perfectly identical, high-fidelity qubits. Our work shows that the QCCD architecture built around these qubits will provide high performance quantum computers, likely enabling important near-term demonstrations such as quantum error correction and quantum advantage.