Vacuum-Gap Capacitors for Low-Loss Superconducting Resonant Circuits

Abstract

Low-loss microwave components are used in many superconducting resonant circuits from multiplexed readouts of low-temperature detector arrays to quantum bits. Two-level system defects in amorphous dielectric materials cause excess energy loss. In an effort to improve capacitor components, we have used optical lithography and micromachining techniques to develop superconducting parallel-plate capacitors in which lossy dielectrics are replaced by vacuum gaps. Resonance measurements at 50 mK on lumped LC circuits that incorporate these vacuum-gap capacitors (VGCs) reveal loss tangents at low powers as low as 4x10^{-5}, significantly lower than with capacitors using amorphous dielectrics. VGCs are structurally robust, small, and easily scaled to capacitance values above 100 pF.

5 pages, 6 figures, .docx format

References in corpus (4)

• Decoherence in Josephson Qubits from Dielectric Loss
• Experimental evidence for a surface distribution of two-level systems in superconducting lithographed microwave resonators
• State tomography of capacitively shunted phase qubits with high fidelity
• Frequency-Tunable Josephson Junction Resonator for Quantum Computing

Cited by in corpus (8)

• Towards understanding two-level-systems in amorphous solids -- Insights from quantum circuits
• Wirebond crosstalk and cavity modes in large chip mounts for superconducting qubits
• Low-loss superconducting resonant circuits using vacuum-gap-based microwave components
• Vacuum-gap transmon qubits realized using flip-chip technology
• Evidence for hydrogen two-level systems in atomic layer deposition oxides
• Quantum collective motion of macroscopic mechanical oscillators
• Compact vacuum gap transmon qubits: Selective and sensitive probes for superconductor surface losses
• Fabrication and characterization of vacuum-gap microstrip resonators