Extended Approach for Efficient Coupling Strength Determination for Superconducting Qubit

Zhen Luo, Ivan Tsitsilin, Christian Schneider, Marco Dietz, Amelie Hagelauer

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

In the design of superconducting quantum chips, the control and readout of the quantum bit (qubit) are realized through interactions with other components in the circuit, such as drive lines, flux lines and readout resonator. Depending on the design, these interactions employ either an inductive or capacitive coupling scheme. Note that every interaction governs critical performance metrics for the chip, including gate fidelity, readout speed, and coherence times, a more effective and precise approach to extract the strength of the coupling is necessary. For most qubit designs, the structure of the qubit typically remains in the electrically small regime. Therefore, simulation software based on static fields and the Method of Moments (MoM), such as Q3D, is still applicable in most instances. However, as the number of qubits on a chip increases, Q3D faces challenges in effectively addressing the complex coupling and crosstalk issues present on the chip. In this work, we extend the lumped-element-based qubit model by using microwave network parameters and thus enable the simulation of the qubit for the Finite Element Method (FEM)-based 3D electromagnetic simulation software, such as HFSS. This approach is suitable for the determination of the capacitive coupling strength between the qubit and the drive line, as well as readout circuits. Furthermore, to address the inductive coupling between the qubit and the flux line, we propose a method in this work that directly computes the mutual inductance, which is implemented by determining the magnetic flux through the DC SQUID area, generated by the current port excitation in HFSS. The proposed methodologies not only effectively extracts the key qubit design parameters, but also offer broader applicability for analysing complex crosstalk in multi-qubit chip designs.

Original languageEnglish
Title of host publicationProceedings - 2023 IEEE International Conference on Quantum Computing and Engineering, QCE 2023
EditorsHausi Muller, Yuri Alexev, Andrea Delgado, Greg Byrd
PublisherInstitute of Electrical and Electronics Engineers Inc.
Pages288-289
Number of pages2
ISBN (Electronic)9798350343236
DOIs
StatePublished - 2023
Event4th IEEE International Conference on Quantum Computing and Engineering, QCE 2023 - Bellevue, United States
Duration: 17 Sep 202322 Sep 2023

Publication series

NameProceedings - 2023 IEEE International Conference on Quantum Computing and Engineering, QCE 2023
Volume2

Conference

Conference4th IEEE International Conference on Quantum Computing and Engineering, QCE 2023
Country/TerritoryUnited States
CityBellevue
Period17/09/2322/09/23

Keywords

  • FEM simulation
  • coupling strength
  • quantum engineering
  • qubit modelling
  • superconducting qubit

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