26th Australian Institute of Physics Congress and the Australian and New Zealand Conference on Optics and Photonics

Engineering package-mode-free environments for microwave-regime solid-state qubits

Not scheduled

20m

Belinda Hutchinson Building (The University of Sydney )

Contributed Oral AIP | Quantum Science and Technology (QST)

Speaker

Giorge Gemisis (University of Technology Sydney)

Description

Multiple leading quantum computing technology platforms are based on microwave-frequency qubits embedded in superconducting electronic circuits. Due to loss and decoherence constraints, these systems require cryogenic environments and electromagnetic shielding to suppress unwanted electromagnetic interactions, blackbody radiation, quasiparticle interactions and spurious modes that can degrade coherence or introduce experimental interference (Corcoles et.al, Nat.Commun 6:6979, 2015)

Device and on-chip circuit design has been studied extensively to improve device performance, with significant advances achieved, e.g. in circuit QED systems, through using novel device geometries and novel materials to reduce system losses and enhance qubit coherence (Place et.al, Nat.Commun 12:1779, 2021), or deep substrate etching to reduce dielectric loss (Bruno et.al Appl. Phys. Lett. 106:182601, 2015). As these technologies have begun reaching industry scales, attention has also turned to the optimisation of device packaging (Krayzman et.al, Appl.Phys.Lett 124:204001, 2024). As qubits have improved, it is now becoming more likely for device or processor performance to be limited by packaging constraints (Huang et.al, PRXQuantum.2.020306, 2021).

In this work, we investigate the influence of packaging design on a device's microwave environment in relation to spurious electromagnetic modes that can contribute to decoherence and control errors by coupling qubits to the environment and each other. We show that careful device-package co-design is essential, as the common practice of simulating devices and packaging in isolation fails to correctly describe the electromagnetic mode environment, which it turns out can depend sensitively on the combined device-package geometry, including on often-overlooked features of device circuitry. For example, we show how spurious mode frequencies and spatial distributions are strongly affected by manufacturing tolerances and how grounding of device circuits is implemented. We evaluate packaging design strategies for suppressing unwanted modes and study the minimum modifications required to eliminate modes from frequency ranges of interest.