Automated design of superconducting circuits and its application to 4-local couplers

Tim Menke,Florian Häse,Simon Gustavsson,William D Oliver,Andrew J Kerman,Alán Aspuru-Guzik

doi:10.1038/s41534-021-00382-6

Abstract

Superconducting circuits have emerged as a promising platform to build quantum processors. The challenge of designing a circuit is to compromise between realizing a set of performance metrics and reducing circuit complexity and noise sensitivity. At the same time, one needs to explore a large design space, and computational approaches often yield long simulation times. Here, we automate the circuit design task using SCILLA. The software SCILLA performs a parallelized, closed-loop optimization to design superconducting circuit diagrams that match predefined properties, such as spectral features and noise sensitivities. We employ it to design 4-local couplers for superconducting flux qubits and identify a circuit that outperforms an existing proposal with a similar circuit structure in terms of coupling strength and noise resilience for experimentally accessible parameters. This work demonstrates how automated design can facilitate the development of complex circuit architectures for quantum information processing.

Highlights

The promise of quantum computing to surpass the capabilities of classical computers relies on a robust and scalable underlying hardware architecture
It is possible to design a wide variety of qubits and qubit–qubit coupling schemes at the circuit diagram level and realize them in nanofabricated devices[4,6]
As a benchmark for the automated design software, we define the target to be a capacitively shunted (C-shunt) flux qubit. This is a design variant of the flux qubit that has been shown to yield improved reproducibility and coherence for quantum information processing applications[29,30,31]. It is well-suited for strong qubit–qubit coupling in the quantum simulation and annealing context[28]

Summary

Introduction

The promise of quantum computing to surpass the capabilities of classical computers relies on a robust and scalable underlying hardware architecture. Superconducting circuits have proven to be a well-suited platform due to their design versatility[4] Their quantum behavior arises from the interaction of modes that are set by effective inductances, capacitances, and nonlinear Josephson junction elements in the circuit[5]. In this way, it is possible to design a wide variety of qubits and qubit–qubit coupling schemes at the circuit diagram level and realize them in nanofabricated devices[4,6]. In other fields of science and engineering, automated discovery and inverse design have emerged as a solution to a variety of design problems All of these problems share the task to identify a set of parameters for which a system of interest yields desired target properties. In the physical sciences context, automated discovery has been applied to nanophotonic on-chip devices[7,8], complex quantum state generation in optical platforms[9,10], entanglement creation and removal in superconducting circuits[11], and further problems in many-body physics[12,13] and chemistry[14,15,16]

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Results

Conclusion