John D'Ewart
A5024533789- Superconducting and THz Device Technology
- Particle accelerators and beam dynamics
- Radio Astronomy Observations and Technology
- Superconducting Materials and Applications
- Particle Accelerators and Free-Electron Lasers
- Quantum and electron transport phenomena
- Microwave Engineering and Waveguides
- Quantum Information and Cryptography
- Quantum Computing Algorithms and Architecture
- Soil Moisture and Remote Sensing
- Advanced Data Storage Technologies
- Parallel Computing and Optimization Techniques
- Physics of Superconductivity and Magnetism
- Advanced Computational Techniques and Applications
- Advancements in PLL and VCO Technologies
- Distributed and Parallel Computing Systems
- Cosmology and Gravitation Theories
- Radio Frequency Integrated Circuit Design
- Radiation Detection and Scintillator Technologies
- Dark Matter and Cosmic Phenomena
- Theology and Philosophy of Evil
- Radiation Therapy and Dosimetry
- Interconnection Networks and Systems
- Advanced Control Systems Optimization
- Particle Detector Development and Performance
SLAC National Accelerator Laboratory
2018-2023
Stanford University
2019-2021
Kavli Institute for Particle Astrophysics and Cosmology
2021
Princeton University
2021
University of California, San Diego
2021
National Institute of Standards and Technology
2021
University of Colorado Boulder
2021
Quantum error correction with erasure qubits promises significant advantages over standard due to favorable thresholds for errors. To realize this advantage in practice requires a qubit which nearly all errors are such errors, and the ability check without dephasing qubit. We demonstrate that “dual-rail qubit” consisting of pair resonantly coupled transmons can form highly coherent qubit, where transmon <a:math xmlns:a="http://www.w3.org/1998/Math/MathML"...
To solve problems of practical importance1,2, quantum computers probably need to incorporate error correction, in which a logical qubit is redundantly encoded many noisy physical qubits3–5. The large physical-qubit overhead associated with correction motivates the search for more hardware-efficient approaches6–18. Here, using superconducting circuit19, we realize memory formed from concatenation bosonic cat qubits an outer repetition code distance d = 5 (ref. 10). A stabilizing circuit...
The Simons Observatory (SO) is a ground-based cosmic microwave background (CMB) experiment sited on Cerro Toco in the Atacama Desert Chile that promises to provide breakthrough discoveries fundamental physics, cosmology, and astrophysics. Supported by Foundation, Heising-Simons with contributions from collaborating institutions, SO will see first light 2021 start five year survey 2022. has 287 collaborators 12 countries 53 including 85 students 90 postdocs. its currently funded form...
We describe the newest generation of SLAC Microresonator RF (SMuRF) electronics, a warm digital control and readout system for microwave-frequency resonator-based cryogenic detector multiplexer systems, such as microwave superconducting quantum interference device multiplexers (μmux) or kinetic inductance detectors. Ultra-sensitive measurements in particle physics astronomy increasingly rely on large arrays sensors, which turn necessitate highly multiplexed accompanying room-temperature...
A microwave SQUID multiplexer ($\mu$MUX) has been optimized for coupling to large arrays of superconducting transition-edge sensor (TES) bolometers. We present the scalable cryogenic chip design in a 1820-channel configuration 4-8 GHz rf band. The key metrics yield, sensitivity, and crosstalk are determined through measurements 455 readout channels, which span 4-5 GHz. median white-noise level is 45 pA/$\sqrt{\textrm{Hz}}$, evaluated at 2 Hz, with 1/f knee $\leq$ 20 mHz after common-mode...
The next generation of cryogenic CMB and submillimeter cameras under development require densely instrumented sensor arrays to meet their science goals. readout large numbers (~10,000-100,000 per camera) sub-Kelvin sensors, for instance as proposed the CMB-S4 experiment, will substantial improvements in cold warm techniques. To reduce cost integration complexity, efforts are presently focused on achieving higher multiplexing density while maintaining noise subdominant intrinsic detector...
In order to solve problems of practical importance, quantum computers will likely need incorporate error correction, where a logical qubit is redundantly encoded in many noisy physical qubits. The large physical-qubit overhead typically associated with correction motivates the search for more hardware-efficient approaches. Here, using microfabricated superconducting circuit, we realize memory formed from concatenation bosonic cat qubits an outer repetition code distance $d=5$. are passively...
The LCLS2 is a CW superconducting LINAC driven X-ray free electron laser under construction at SLAC. high beam rate of up to 1MHz, and ability deliver electrons multiple undulators dumps, results in diagnostics control system that requires real time data processing programmable logic. SLAC Technical Innovation Directorate has developed common hardware firmware platform for instrumentation based on the ATCA crate format. FPGAs are located carrier cards, front ends A-D / D-A AMC cards...
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We present the details of a simulation suite for modeling effects readout with SLAC Microresonator RF (SMuRF) electronics. The SMuRF electronics are warm and control system use superconducting microwave resonator-based detector systems. has been used BICEP/Keck program will be on upcoming Simons Observatory BICEP Array experiments. This is software implementation main algorithms offline analysis, modeling, study. firmware-implemented calibration, resonator frequency estimation, tone tracking...
LCLS-II's high beam rate of almost 1MHz and the requirement that several high-performance systems (such as MPS, BPM, LLRF, timing etc.) shall resolve individual bunches precludes use a traditional software based control system but requires many core services to be implemented in FPGA logic. SLAC has created comprehensive open-source firmware framework which implements commonly used blocks (e.g., timing, globally-synchronized fast data buffers, diagnostic capture), libraries (Ethernet...
To enable the next-generation of bolometric cameras, we are developing microwave SQUID multiplexer (μMUX). Upcoming receivers such as Simons Observatory, CCAT-prime, BICEP array, Ali-CPT, and CMB-S4 plan to instrument focal planes with 50,000-500,000 sensors. Sensor count is achieved by tiling many 150 mm-diameter densely packed detector arrays into these planes. The fabrication quality large-format bolometer has been demonstrated now mature. In contrast, readout technology required for...
The Linac Coherent Light Source II (LCLS-II) is a major upgrade of the LCLS facility at SLAC, scheduled to start operations in 2020. High Performance Systems (HPS) defines set LCLS-II controls sub-systems which are directly impacted by its 1 MHz operation. It formed around few key concepts: ATCA based packaging, digital and analog application boards, 10G Ethernet interconnections for controls. Common Platform provides common parts HPS term hardware, firmware, software. Software (CPSW)...