Modular QCCD system

Trapped ions (TIs) are a leading candidate for building Noisy Intermediate-Scale Quantum (NISQ) hardware. TI qubits have fundamental advantages over other technologies, featuring high qubit quality, coherence time, and qubit connec- tivity. However, current TI systems are small in size and typically use a single trap architecture, which has fundamen- tal scalability limitations. To progress toward the next major milestone of 50–100 qubit TI devices, a modular architecture termed the Quantum Charge Coupled Device (QCCD) has been proposed. In a QCCD-based TI device, small traps are connected through ion shuttling. While the basic hardware components for such devices have been demonstrated, building a 50–100 qubit system is challenging because of a wide range of design possibilities for trap sizing, communi- cation topology, and gate implementations and the need to match diverse application resource requirements. Toward realizing QCCD-based TI systems with 50–100 qubits, we perform an extensive application-driven architec- tural study evaluating the key design choices of trap sizing, communication topology, and operation implementation methods. To enable our study, we built a design toolflow, which takes a QCCD architecture’s parameters as input, along with a set of applications and realistic hardware per- formance models. Our toolflow maps the applications onto the target device and simulates their execution to compute metrics such as application run time, reliability, and device noise rates. Using six applications and several hardware design points, we show that trap sizing and communication topology choices can impact application reliability by up to three orders of magnitude. Microarchitectural gate imple- mentation choices influence reliability by another order of magnitude. From these studies, we provide concrete recom- mendations to tune these choices to achieve highly reliable and performant application executions. With industry and academic efforts underway to build TI devices with 50–100 qubits, our insights have the potential to influence QC hard- ware in the near future and accelerate the progress toward practical QC systems. DOI 10.1145/3511064

Prakash Murali, Dripto M. Debroy, Kenneth R. Brown, and Margaret Martonosi