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Superconducting quantum computing architectures comprise resonators and qubits that experience energy loss due to two-level systems (TLS) in bulk and interfacial dielectrics. Understanding these losses is critical to improving performance…
Long-term stability of superconducting microwave resonators is essential for scalable quantum technologies; however, surface and interface degradation continue to limit device stability. Here, we demonstrate exceptional stability in…
Utilizing tantalum (Ta) in superconducting circuits has led to significant improvements, such as high qubit lifetimes and quality factors in both qubits and resonators, underscoring the importance of material optimization in quantum device…
Superconducting coplanar waveguide (SCPW) resonators, key components for quantum computing and sensing applications, require a high internal quality factor (Qi) for effective qubit readout and quantum sensing applications. Minimizing…
This white paper presents a single-layer mask, found at https://github.com/Boulder-Cryogenic-Quantum-Testbed/simple-resonator-mask. It is designed for fabrication of superconducting microwave resonators towards 1:1 comparisons of dielectric…
For practical superconducting quantum processors, orders of magnitude improvement in coherence is required, motivating efforts to optimize hardware design and explore new materials. Among the latter, the coherence of superconducting…
High quality factor coplanar resonators are critical elements in superconducting quantum circuits. We describe the design, fabrication and measurement of stepped impedance resonators (SIRs), which are more compact in size than commonly used…
Despite mounting evidence that materials imperfections are a major obstacle to practical applications of superconducting qubits, connections between microscopic material properties and qubit coherence are poorly understood. Here, we perform…
Superconducting microwave circuits show great potential for practical quantum technological applications such as quantum information processing. However, fast and on-demand initialization of the quantum degrees of freedom in these devices…
We present systematic measurements of the quality factors of surface acoustic wave (SAW) resonators on ST-X quartz in the gigahertz range at a temperature of $10 \, \textrm{mK}$. We demonstrate a internal quality factor $Q_\mathrm{i}$…
Material research is a key frontier in advancing superconducting qubit and circuit performance. In this work, we develop a simple and broadly applicable framework for accurately characterizing two-level system (TLS) loss using internal…
We report development and measurement of a micro-fabricated compact high-temperature superconducting (HTS) metamaterial atom operating at a frequency as low as $\sim$ 53MHz. The device is a planar spiral resonator patterned out of a…
A hybrid device comprising a (Al)GaAs quantum dot heterostructure and a LiNbO$_3$ surface acoustic wave resonator is fabricated by heterointegration. High acoustic quality factors $Q>4000$ are demonstrated for an operation frequency…
We present a systematic analysis of the internal losses of superconducting coplanar waveguide microwave resonators based on niobium thin films on silicon substrates. In particular, we investigate losses introduced by Nb/Al interfaces in the…
Characterizing superconducting microwave resonators with highly dissipative elements is a technical challenge, but a requirement for implementing and understanding the operation of hybrid quantum devices involving dissipative elements, e.g.…
We present measurements of the temperature and power dependence of the resonance frequency and frequency noise of superconducting niobium thin-film coplanar waveguide resonators, carried out at temperatures well below the superconducting…
Superconducting high kinetic inductance elements constitute a valuable resource for quantum circuit design and millimeter-wave detection. Granular aluminum (GrAl) in the superconducting regime is a particularly interesting material since it…
Manipulating the propagation of electromagnetic waves through sub-wavelength sized artificial structures is the core function of metamaterials. Resonant structures, such as split ring resonators, play the role of artificial "atoms" and…
Superconducting enclosures will be key components of scalable quantum computing devices based on circuit quantum electrodynamics (cQED). Within a densely integrated device, they can protect qubits from noise and serve as quantum memory…
The use of $\alpha$-tantalum in superconducting circuits has enabled a considerable improvement of the coherence time of transmon qubits. The standard approach to grow $\alpha$-tantalum thin films on silicon involves heating the substrate,…