Quantum Instruction Set Design for Performance

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A quantum instruction set is where quantum hardware and software meet. We develop new characterization and compilation techniques for non-Clifford gates to accurately evaluate different quantum instruction set designs. We specifically apply them to our fluxonium processor that supports mainstream instruction iSWAP by calibrating and characterizing its square root SQiSW. We measure a gate fidelity of up to 99.72% with an average of 99.31% and realize Haar random two-qubit gates using SQiSW with an average fidelity of 96.38%. This is an average error reduction of 41% for the former and a 50% reduction for the latter compared to using iSWAP on the same processor. This shows designing the quantum instruction set consisting of SQiSW and single-qubit gates on such platforms leads to a performance boost at almost no cost.

Physical Review Letters, 130, 070601