Paul V. Klimov; Andreas Bengtsson; Chris Quintana; Alexandre Bourassa; Sabrina Hong; A. Dunsworth; Kevin J. Satzinger; William P. Livingston; Volodymyr Sivak; Murphy Yuezhen Niu; Trond I. Andersen; Yaxing Zhang; Desmond Chik; Zijun Chen; Charles Neill; Catherine Erickson; Alejandro Grajales Dau; A. Megrant; P. Roushan; Alexander N. Korotkov; J. Kelly; Vadim Smelyanskiy; Yu Chen; Hartmut Neven · 2024 · Nature Communications
Paper
A foundational assumption of quantum error correction theory is that quantum gates can be scaled to large processors without exceeding the error-threshold for fault tolerance. Two major challenges that could become fundamental roadblocks are manufacturing high-performance quantum hardware and engineering a control system that can reach its performance limits. The control challenge of scaling quantum gates from small to large processors without degrading performance often maps to non-convex, high-constraint, and time-dynamic control optimization over an exponentially expanding configuration space. Here we report on a control optimization strategy that can scalably overcome the complexity of such problems. We demonstrate it by choreographing the frequency trajectories of 68 frequency-tunable superconducting qubits to execute single- and two-qubit gates while mitigating computational errors. When combined with a comprehensive model of physical errors across our processor, the strategy suppresses physical error rates by ~3.7× compared with the case of no optimization. Furthermore, it is projected to achieve a similar performance advantage on a distance-23 surface code logical qubit with 1057 physical qubits. Our control optimization strategy solves a generic scaling challenge in a way that can be adapted to a variety of quantum operations, algorithms, and computing architectures.
Analysis
This paper presents a scalable control optimization strategy to overcome the complexity of engineering control systems for large-scale quantum processors, demonstrating significant error suppression and projecting advantages for logical qubits.
Discovery
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