4 research outputs found
Broadband SNAIL parametric amplifier with microstrip impedance transformer
Josephson parametric amplifiers have emerged as a promising platform for
quantum information processing and squeezed quantum states generation.
Travelling wave and impedance-matched parametric amplifiers provide broad
bandwidth for high-fidelity single-shot readout of multiple qubit
superconducting circuits. Here, we present a quantum-limited 3-wave-mixing
parametric amplifier based on superconducting nonlinear asymmetric inductive
elements (SNAILs), whose useful bandwidth is enhanced with an on-chip
two-section impedance-matching circuit based on microstrip transmission lines.
The amplifier dynamic range is increased using an array of sixty-seven SNAILs
with 268 Josephson junctions, forming a nonlinear quarter-wave resonator.
Operating in a current-pumped mode, we experimentally demonstrate an average
gain of across bandwidth, along with an average saturation
power of , which can go as high as with quantum-limited
noise performance. Moreover, the amplifier can be fabricated using a simple
technology with just a one e-beam lithography step. Its central frequency is
tuned over a several hundred megahertz, which in turn broadens the effective
operational bandwidth to around .Comment: 7 pages, 3 figure
Improving Josephson junction reproducibility for superconducting quantum circuits: junction area fluctuation
Josephson superconducting qubits and parametric amplifiers are prominent
examples of superconducting quantum circuits that have shown rapid progress in
recent years. With the growing complexity of such devices, the requirements for
reproducibility of their electrical properties across a chip have become
stricter. Thus, the critical current variation of the Josephson junction,
as the most important electrical parameter, needs to be minimized. Critical
current, in turn, is related to normal-state resistance the Ambegaokar-Baratoff
formula, which can be measured at room temperature. Here, we focus on the
dominant source of Josephson junction critical current non-uniformity junction
area variation. We optimized Josephson junctions fabrication process and
demonstrate resistance variation of and across
and chip areas, respectively. For a
wide range of junction areas from to we
ensure a small linewidth standard deviation of measured over 4500
junctions with linear dimensions from to . The developed process
was tested on superconducting highly coherent transmon qubits and a nonlinear asymmetric inductive element parametric
amplifier
Deep multilevel wet etching of fused silica glass microstructures in BOE solution
Abstract Fused silica glass is a material of choice for micromechanical, microfluidic, and optical devices due to its chemical resistance, optical, electrical, and mechanical performance. Wet etching is the key method for fabricating of such microdevices. Protective mask integrity is a big challenge due extremely aggressive properties of etching solution. Here, we propose multilevel microstructures fabrication route based on fused silica deep etching through a stepped mask. First, we provide an analysis of a fused silica dissolution mechanism in buffered oxide etching (BOE) solution and calculate the main fluoride fractions like HF 2 - , F - , ( H F ) 2 as a function of pH and NH4F:HF ratio. Then, we experimentally investigate the influence of BOE composition (1:1–14:1) on the mask resistance, etch rate and profile isotropy during deep etching through a metal/photoresist mask. Finally, we demonstrate a high-quality multilevel over-200 μm etching process with the rate up to 3 μm/min, which could be of a great interest for advanced microdevices with flexure suspensions, inertial masses, microchannels, and through-wafer holes
Optical hydrogen sensing with high-Q guided-mode resonance of Al2O3/WO3/Pd nanostructure
Abstract Nanostructure based on a dielectric grating (Al2O3), gasochromic oxide (WO3) and catalyst (Pd) is proposed as a hydrogen sensor working at the room temperature. In the fabricated structure, the Pd catalyst film was as thin as 1 nm that allowed a significant decrease in the optical absorption. A high-Q guided-mode resonance was observed in a transmission spectrum at normal incidence and was utilized for hydrogen detection. The spectra were measured at 0–0.12% of hydrogen in a synthetic air (≈ 80% N 2 and 20% O 2 ). The detection limit below 100 ppm of hydrogen was demonstrated. Hydrogen was detected in the presence of oxygen, which provides the sensor recovery but suppresses the sensor response. Sensor response was treated by the principal component analysis (PCA), which effectively performs noise averaging. Influence of temperature and humidity was measured and processed by PCA, and elimination of the humidity and temperature effects was performed. Square root dependence of the sensor response on the hydrogen concentration (Sievert’s law) was observed. Sensor calibration curve was built, and the sensor resolution of 40 ppm was found. Long term stability of the sensor was investigated. Particularly, it was shown that the sensor retains its functionality after 6 months and dozens of acts of response to gas