4 research outputs found
Tunable inductive coupler for high fidelity gates between fluxonium qubits
The fluxonium qubit is a promising candidate for quantum computation due to
its long coherence times and large anharmonicity. We present a tunable coupler
that realizes strong inductive coupling between two heavy-fluxonium qubits,
each with MHz frequencies and GHz anharmonicities. The coupler
enables the qubits to have a large tuning range of coupling
strengths ( to MHz). The coupling strength is kHz
across the entire coupler bias range, and Hz at the coupler off-position.
These qualities lead to fast, high-fidelity single- and two-qubit gates. By
driving at the difference frequency of the two qubits, we realize a
gate in ns with fidelity , and by driving
at the sum frequency of the two qubits, we achieve a
gate in ns with fidelity . This latter gate is only 5 qubit
Larmor periods in length. We run cross-entropy benchmarking for over
consecutive hours and measure stable gate fidelities, with
drift () and
drift .Comment: 16 pages, 14 figure
The United States COVID-19 Forecast Hub dataset
Academic researchers, government agencies, industry groups, and individuals have produced forecasts at an unprecedented scale during the COVID-19 pandemic. To leverage these forecasts, the United States Centers for Disease Control and Prevention (CDC) partnered with an academic research lab at the University of Massachusetts Amherst to create the US COVID-19 Forecast Hub. Launched in April 2020, the Forecast Hub is a dataset with point and probabilistic forecasts of incident cases, incident hospitalizations, incident deaths, and cumulative deaths due to COVID-19 at county, state, and national, levels in the United States. Included forecasts represent a variety of modeling approaches, data sources, and assumptions regarding the spread of COVID-19. The goal of this dataset is to establish a standardized and comparable set of short-term forecasts from modeling teams. These data can be used to develop ensemble models, communicate forecasts to the public, create visualizations, compare models, and inform policies regarding COVID-19 mitigation. These open-source data are available via download from GitHub, through an online API, and through R packages
Computer-aided quantization and numerical analysis of superconducting circuits
The development of new superconducting circuits and the improvement of
existing ones rely on the accurate modeling of spectral properties which are
key to achieving the needed advances in qubit performance. Systematic circuit
analysis at the lumped-element level, starting from a circuit network and
culminating in a Hamiltonian appropriately describing the quantum properties of
the circuit, is a well-established procedure, yet cumbersome to carry out
manually for larger circuits. We present work utilizing symbolic computer
algebra and numerical diagonalization routines versatile enough to tackle a
variety of circuits. Results from this work are accessible through a newly
released module of the scqubits package.Comment: 12 pages, 7 figures, 1 table, associated Python package:
https://github.com/scqubits/scqubits, added references, corrected typos and
updated numerical value
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Tunable Inductive Coupler for High-Fidelity Gates Between Fluxonium Qubits
The fluxonium qubit is a promising candidate for quantum computation due to its long coherence times and large anharmonicity. We present a tunable coupler that realizes strong inductive coupling between two heavy-fluxonium qubits, each with approximately -MHz frequencies and approximately -GHz anharmonicities. The coupler enables the qubits to have a large tuning range of coupling strengths (− to 75 MHz). The coupling strength is < 3 kHz across the entire coupler bias range and < 100 Hz at the coupler off position. These qualities lead to fast high-fidelity single- and two-qubit gates. By driving at the difference frequency of the two qubits, we realize a gate in 258 ns with fidelity 99.72%, and by driving at the sum frequency of the two qubits, we achieve a gate in 102 ns with fidelity 99.91%. This latter gate is only five qubit Larmor periods in length. We run cross-entropy benchmarking for over 20 consecutive hours and measure stable gate fidelities, with drift () < and drift <