A5024345309- Quantum and electron transport phenomena
- Physics of Superconductivity and Magnetism
- Surface and Thin Film Phenomena
- Particle accelerators and beam dynamics
- Quantum Computing Algorithms and Architecture
- Magnetic properties of thin films
- Quantum Information and Cryptography
- Superconductivity in MgB2 and Alloys
- Semiconductor materials and devices
- Advancements in Semiconductor Devices and Circuit Design
- Superconducting and THz Device Technology
- Nanowire Synthesis and Applications
- Semiconductor Quantum Structures and Devices
- Advanced Thermodynamics and Statistical Mechanics
- Ion-surface interactions and analysis
- Quantum-Dot Cellular Automata
- Electron and X-Ray Spectroscopy Techniques
- Quantum Mechanics and Applications
- Diamond and Carbon-based Materials Research
- Advanced Materials Characterization Techniques
- Gyrotron and Vacuum Electronics Research
- Microwave Engineering and Waveguides
- Metal and Thin Film Mechanics
Rigetti Computing (United States)
2018-2025
Harnessing techniques from analog signal processing, we establish a new path for large-scale quantum computation.
A central challenge in building a scalable quantum computer with superconducting qubits is the execution of high-fidelity two-qubit gates presence many resonant elements. As more elements are added to architecture, and as multiplicity their couplings grows, design's frequency space becomes crowded, performance suffers. The authors present way address this difficulty: selective activation interactions between transmon fixed those tunable frequency. This depends on both amplitude modulation,...
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...
We describe a microfabrication process for superconducting through-silicon vias appropriate use in qubit quantum processors. With sloped-wall via geometry, we can non-conformal metal deposition methods such as electron-beam evaporation and sputtering, which reliably deposit high quality films. Via superconductivity is validated by demonstrating zero via-to-via resistance below the critical temperature of aluminum.
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 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...
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 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 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...
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>...
We report on the fabrication and metrology of superconducting caps for qubit circuits. As part a 3D quantum integrated circuit architecture, cap chip forms upper half an enclosure that provides isolation, increases vacuum participation ratio, improves performance individual resonant elements. Here, we demonstrate such can be reliably fabricated, placed chip, form connections to circuit.
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...
Continued advances in superconducting qubit performance require more detailed understandings of the many sources decoherence. Within these devices, two-level systems arise due to defects, interfaces, and grain boundaries are thought be a major source decoherence at millikelvin temperatures. In addition Al, Nb is commonly used metallization layer qubits. Consequently, significant effort required develop qualify processes that mitigate defects films. As fabrication complete qubits their...
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...
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 cavities, as well various Nb resonator films transomon qubits. Using ultrafast pump-probe spectroscopy regime minimal condensate depletion, we were able to isolate coherence pair-breaking responses. Our results reveal both similarities notable differences temperature- magnetic field-dependent samples....
Niobium is commonly used for superconducting quantum systems as readout resonators, capacitors, and interconnects. The coherence time of the qubits mainly limited by microwave dissipation attributed to two-level system defects at interfaces, such Nb/Si Nb/air interface. One way improve interface quality thermal annealing, shown extensive studies in 3D radio frequency (SRF) cavities. However, it unclear how microstructure chemistry structures change during heat treatment. To address this...
Niobium is commonly used for superconducting quantum systems as readout resonators, capacitors, and interconnects. But structural defects at the Nb/Si air/Nb interface may be a major source of two-level system (TLS), which are detrimental to device's coherence time. Thus, identifying understanding microscopic origin possible TLS in Nb-based devices their relationship processing key qubit performance improvement. This work studied structure thermal stability Nb films deposited on Si wafers by...
London penetration depth was measured in niobium foils, thin films, single crystals, and superconducting radio-frequency (SRF) cavity pieces cut out from different places. The low-temperature (T<Tc/3) variation, sensitive to the low-energy quasiparticles with states inside gap, differs dramatically between types of samples. With help phenomenological modeling, we correlate these behaviors known pair-breaking mechanisms show that such measurements may distinguish mechanisms, as hydrides...
chemical properties after irradiation for feedback process. A novel approach is presented to determine the local burnup in irradiated fuels using isotopic quantification obtained by Atom Probe Tomography (APT). Considering volume of sample used (<100?µm3) APT experiments lift-out process a scanning electron microscope equipped with Focused Ion Beam (FIB), method determines from nuclear fuel, where minimal amount waste produced. In this work, three samples were analyzed different conditions...