A5060321875- Quantum and electron transport phenomena
- Physics of Superconductivity and Magnetism
- Surface and Thin Film Phenomena
- Quantum Information and Cryptography
- Magnetic properties of thin films
- Semiconductor materials and devices
- Semiconductor Quantum Structures and Devices
- Particle accelerators and beam dynamics
- Superconducting and THz Device Technology
- Mechanical and Optical Resonators
- Silicon and Solar Cell Technologies
- Quantum Computing Algorithms and Architecture
- Microwave Dielectric Ceramics Synthesis
- Ion-surface interactions and analysis
- Integrated Circuits and Semiconductor Failure Analysis
- Superconductivity in MgB2 and Alloys
- 2D Materials and Applications
- Acoustic Wave Resonator Technologies
- Photonic and Optical Devices
- Advanced Frequency and Time Standards
- Diamond and Carbon-based Materials Research
- Chalcogenide Semiconductor Thin Films
- Advanced MEMS and NEMS Technologies
- Electronic and Structural Properties of Oxides
- Radiation Detection and Scintillator Technologies
Rigetti Computing (United States)
2022-2025
Ames National Laboratory
2024
Iowa State University
2024
Arizona State University
2011-2021
Northrop Grumman (United States)
2021
Tempe Union High School District
2020
Improving the qubit's lifetime (T1) is crucial for fault-tolerant quantum computing. Recent advancements have shown that replacing niobium (Nb) with tantalum (Ta) as base metal significantly increases T1, likely due to a less lossy native surface oxide. However, understanding formation mechanism and nature of both oxides still limited. Using aberration-corrected transmission electron microscopy energy loss spectroscopy, we found Ta oxide has fewer suboxides than Nb We observed an abrupt...
Superconducting quantum bits (qubits) rely on ultra-thin, amorphous oxide tunneling barriers that can have significant inhomogeneities and defects as grown. This result in relatively large uncertainties deleterious effects the circuits, limiting scalability. Finding a robust solution to junction reproducibility problem has been long-standing goal field. Here, we demonstrate transformational technique for controllably tuning electrical properties of aluminum-oxide tunnel junctions. is...
We conducted a comprehensive study of the non-equilibrium dynamics Cooper pair breaking, quasiparticle (QP) generation, and relaxation in niobium (Nb) cut from superconducting radio-frequency (SRF) cavities, as well various Nb resonator films transmon qubits. Using ultrafast pump–probe spectroscopy, we were able to isolate coherence pair-breaking responses. Our results reveal both similarities notable differences temperature- magnetic-field-dependent SRF cavity thin-film samples. Moreover,...
Superconducting qubits have emerged as a potentially foundational platform technology for addressing complex computational problems deemed intractable with classical computing. Despite recent advances enabling multiqubit designs that exhibit coherence lifetimes on the order of hundreds μs, material quality and interfacial structures continue to curb device performance. Two-level system defects in thin superconducting film adjacent dielectric regions introduce stochastic noise dissipate...
Superconducting thin films of niobium have been extensively employed in transmon qubit architectures. Although these architectures demonstrated improvements recent years, further performance through materials engineering will aid large-scale deployment. Here, we use information retrieved from secondary ion mass spectrometry and electron microscopy to conduct a detailed assessment the surface oxide that forms ambient conditions for test devices patterned film. We observe this exhibits varying...
Superconducting Nb thin films have recently attracted significant attention due to their utility for quantum information technologies. In the processing of films, fluoride-based chemical etchants are commonly used remove surface oxides that known affect superconducting devices adversely. However, these same can also introduce hydrogen form hydrides, potentially negatively impacting microwave loss performance. Here, we present comprehensive materials characterization hydrides formed in as a...
Abstract Radioactivity was recently discovered as a source of decoherence and correlated errors for the real-world implementation superconducting quantum processors. In this work, we measure levels radioactivity present in typical laboratory environment (from muons, neutrons, $$\gamma $$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>γ</mml:mi> </mml:math> -rays emitted by naturally occurring radioactive isotopes) most commonly used materials assembly operation...
Superconducting quantum circuits (SQC) are one of the most promising hardware platforms for computing, yet their performance is currently limited by presence various structural defects inside circuit's structure. Despite impressive progress in past decade, a precise understanding origin these from fabrication processes and impact on coherence still lacking. In this study, we performed comprehensive investigation microstructure, superconductivity, resonator quality factor Nb films deposited...
An ultra-thin aluminum oxide layer is a key component for Josephson junctions (JJ) in superconducting quantum bits (qubits). This serves as barrier Cooper pairs tunneling between the electrodes and significantly influences overall performance of junction. In this study, we investigate impact deposition rates on microstructure chemical variation layer, well device's yields qubits' lifetimes. Surprisingly, although roughness thickness improve noticeably with an increasing Al rate from 0.5 Å/s...
This work reports on a comprehensive examination of the electrical and thermal properties vertical Schottky diodes fabricated (2¯01)- (001)-oriented samples β-Ga2O3. The temperature-dependent current–voltage (I–V) capacitance–voltage (C–V) data were gathered analyzed down to 60 K. Deep level transient spectroscopy (DLTS) was used study bulk interface defects in two materials from approx. 325 K In (2¯01) material, an electron trap observed at EC−0.46 eV, with capture cross section 1.6 × 10−14...
Niobium is one of the most studied superconductors, both theoretically and experimentally. It tremendously important for applications, it has highest superconducting transition temperature, ${T}_{c}=9.32$ K, all pure metals. In addition to power applications in alloys, niobium used sensitive magnetosensing, radio-frequency cavities, and, more recently, as circuit metallization layers qubits. A detailed understanding its electronic structure, especially normal state anisotropies, crucial...
Niobium thin films are key components of superconducting microwave resonators. Interest in these devices has increased dramatically because their application quantum systems. Despite tremendous effort to improve performance, loss mechanisms still not well understood. Nb/substrate and Nb/air interfaces likely culprits contributing decoherence ultimately limiting the performance devices. Here, we investigate interface by studying effect hydrogen-passivated H:Si(111) substrates on local...
Niobium thin films on silicon substrate used in the fabrication of superconducting qubits have been characterized using scanning and transmission electron microscopy, electrical transport, magnetization, London penetration depth - based quasiparticle spectroscopy, real-space real-time magneto-optical imaging. We study niobium to provide an example a comprehensive analytical set that may benefit circuits such as those quantum computers. The transition temperature ${T}_{c}=9.35$ K fairly clean...
The fundamental challenge underlying superconducting quantum computing is to characterize heterogeneity and disorder in the circuits. These nonuniform distributions often lead local electric field concentration, charge scattering, dissipation ultimately decoherence. It particularly challenging probe deep sub-wavelength distribution under electromagnetic wave coupling at individual nano-junctions correlate them with structural imperfections from interface boundary, ubiquitous Josephson...
We demonstrate a transformational technique for controllably tuning the electrical properties of fabricated thermally oxidized amorphous aluminum-oxide tunnel junctions. Using conventional test equipment to apply an alternating bias heated barrier, giant increases in room temperature resistance, greater than 70%, can be achieved. The rate resistance change is shown strongly temperature-dependent, and independent junction size sub-micron regime. In order measure their tunneling at mK...
The performance of superconducting qubits is often limited by dissipation and two-level systems (TLS) losses. dominant sources these losses are believed to originate from amorphous materials defects at interfaces surfaces, likely as a result fabrication processes or ambient exposure. Here, we explore novel wet chemical surface treatment the Josephson junction-substrate substrate-air replacing buffered oxide etch (BOE) cleaning process with one that uses hydrofluoric acid followed aqueous...
Abstract The London penetration depth, <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mi>λ</mml:mi> <mml:mo stretchy="false">(</mml:mo> <mml:mi>T</mml:mi> stretchy="false">)</mml:mo> </mml:mrow> </mml:math> , was measured in various forms of niobium, including foils, thin films, single crystals, and samples from superconducting radio-frequency (SRF) cavities. We observed a significant difference at low temperatures, <mml:mo><</mml:mo>...
This paper investigates the properties of thin films chromium-doped Ni80Fe20 (Permalloy) that could potentially be useful in future low-power magnetic memory technologies. The addition chromium reduces saturation magnetization, Ms, which is for low-energy switching, but does not significantly degrade excellent switching host material even down to 10 K, lowest temperature measured, as 2.5 nm. As an example, alloy film composed 15% and 85% has Ms just over half pure Ni80Fe20, with a coercivity...
High-pressure soft sputtering: large area 1T′ phase MoTe<sub>2</sub> thin films were grown at temperatures as low 300 °C.
We present a novel transmon qubit fabrication technique that yields systematic improvements in T$_1$ relaxation times. fabricate devices using an encapsulation strategy involves passivating the surface of niobium and thereby preventing formation its lossy oxide. By maintaining same superconducting metal only varying structure, this comparative investigation examining different capping materials, such as tantalum, aluminum, titanium nitride, gold, film substrates across foundries definitively...