Related papers: Improved superconducting qubit coherence using tit…
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 qubits have been used in the most advanced demonstrations of quantum information processing, and they can be manufactured at-scale using proven semiconductor techniques. This makes them one of the leading technologies in the…
We present a gate-voltage tunable transmon qubit (gatemon) based on planar InAs nanowires that are selectively grown on a high resistivity silicon substrate using III-V buffer layers. We show that low loss superconducting resonators with an…
This study presents a comprehensive investigation into the exceptional superconducting attributes of titanium nitride (TiN) achieved through plasma-enhanced atomic layer deposition (PEALD) on both planar and intricate three-dimensional (3D)…
Analytical formulas are presented for simplified but useful qubit geometries that predict surface dielectric loss when its thickness is much less than the metal thickness, the limiting case needed for real devices. These formulas can thus…
In conventional transmon qubits, decoherence is dominated by a large number of parasitic two-level systems (TLS) residing at the edges of its large area coplanar shunt capacitor and junction leads. Avoiding these defects by improvements in…
Niobium offers the benefit of increased operating temperatures and frequencies for Josephson junctions, which are the core component of superconducting devices. However existing niobium processes are limited by more complicated fabrication…
We demonstrate aluminum-on-silicon planar transmon qubits with time-averaged ${T_1}$ energy relaxation times of up to ${270\,\mu s}$, corresponding to Q = 5 million, and a highest observed value of ${501\,\mu s}$. We use materials analysis…
State-of-the-art transmon qubits rely on large capacitors which systematically improves their coherence due to reduced surface loss participation. However, this approach increases both the footprint and the parasitic cross-coupling and is…
Improving the performance of superconducting qubits and resonators generally results from a combination of materials and fabrication process improvements and design modifications that reduce device sensitivity to residual losses. One…
We have measured the excited state lifetimes in Josephson junction phase and transmon qubits, all of which were fabricated with the same scalable multi-layer process. We have compared the lifetimes of phase qubits before and after removal…
We have demonstrated a novel type of superconducting transmon qubit in which a Josephson junction has been engineered to act as its own parallel shunt capacitor. This merged-element transmon (MET) potentially offers a smaller footprint and…
Superconducting quantum circuits provide a versatile platform for studying quantum materials by leveraging precise microwave control and utilizing the tools of circuit quantum electrodynamics (QED). Hybrid circuit devices incorporating…
We demonstrate a direct writing method for the fabrication of planar Josephson junctions from high quality superconducting niobium titanium nitride (NbTiN) thin films, by creating local disorder using focused He-ion beam irradiation in a…
We demonstrate a substantial reduction in two-level system loss in tantalum coplanar waveguide resonators fabricated on high-resistivity silicon substrates through the use of an ultrathin titanium sacrificial layer. A 0.2nm titanium film,…
In this paper, we investigate the quasi-particle (QP) relaxation of strongly disordered superconducting resonators under optical illumination at different bath temperatures with the Rothwarf and Taylor equations and the gap-broadening…
We report a novel method of growing strongly-disordered superconducting titanium nitride (TiN) thin films by reactive electron-beam deposition. The normal state sheet resistance and superconducting critical temperature (Tc) can be tuned by…
We present a superconducting qubit design that is fabricated in a 2D geometry over a superconducting ground plane to enhance the lifetime. The qubit is coupled to a microstrip resonator for readout. The circuit is fabricated on a silicon…
We demonstrate a planar, tunable superconducting qubit with energy relaxation times up to 44 microseconds. This is achieved by using a geometry designed to both minimize radiative loss and reduce coupling to materials-related defects. At…
We report development and microwave characterization of rf SQUID (Superconducting QUantum Interference Device) qubits, consisting of an aluminium-based Josephson junction embedded in a superconducting loop patterned from a thin film of TiN…