Alexander L. Crook
A5070693516- Quantum Computing Algorithms and Architecture
- Semiconductor materials and devices
- Quantum and electron transport phenomena
- Quantum Information and Cryptography
- Diamond and Carbon-based Materials Research
- Advancements in Semiconductor Devices and Circuit Design
- Neural Networks and Reservoir Computing
- Advanced Electron Microscopy Techniques and Applications
- Silicon Carbide Semiconductor Technologies
- Advanced Data Storage Technologies
- Quantum optics and atomic interactions
- Quantum many-body systems
- Integrated Circuits and Semiconductor Failure Analysis
- Quantum-Dot Cellular Automata
- Topological Materials and Phenomena
- Neural Networks and Applications
- Photonic Crystals and Applications
- Quantum Mechanics and Applications
- Advanced biosensing and bioanalysis techniques
- Advanced X-ray Imaging Techniques
- Electrochemical sensors and biosensors
- Cardiovascular Health and Disease Prevention
- Computational Physics and Python Applications
- Atomic and Subatomic Physics Research
- Random lasers and scattering media
Google (United States)
2022-2024
University of Chicago
2019-2022
University of California, Riverside
2022
University of Pennsylvania
2014-2016
Abstract Practical quantum computing will require error rates well below those achievable with physical qubits. Quantum correction 1,2 offers a path to algorithmically relevant by encoding logical qubits within many qubits, for which increasing the number of enhances protection against errors. However, introducing more also increases sources, so density errors must be sufficiently low performance improve code size. Here we report measurement qubit scaling across several sizes, and...
An outstanding hurdle for defect spin qubits in silicon carbide (SiC) is single-shot readout, a deterministic measurement of the quantum state. Here, we demonstrate readout single defects SiC via spin-to-charge conversion, whereby defect's state mapped onto long-lived charge With this technique, achieve over 80% fidelity without pre- or postselection, resulting high signal-to-noise ratio that enables us to measure long coherence times. Combined with pulsed dynamical decoupling sequences an...
Indistinguishability of particles is a fundamental principle quantum mechanics
Spin defects in silicon carbide have the advantage of exceptional electron spin coherence combined with a near-infrared spin-photon interface, all material amenable to modern semiconductor fabrication. Leveraging these advantages, we integrated highly coherent single neutral divacancy spins commercially available p-i-n structures and fabricated diodes modulate local electrical environment defects. These devices enable deterministic charge-state control broad Stark-shift tuning exceeding 850...
Decoherence limits the physical realization of qubits, and its mitigation is critical for development quantum science technology. We construct a robust qubit embedded in decoherence-protected subspace, obtained by applying microwave dressing to clock transition ground-state electron spin silicon carbide divacancy defect. The universally protected from magnetic, electric, temperature fluctuations, which account nearly all relevant decoherence channels solid state. This culminates an increase...
Silicon carbide has recently been developed as a platform for optically addressable spin defects. In particular, the neutral divacancy in 4H polytype displays an spin-1 ground state and near-infrared optical emission. Here, we present Purcell enhancement of single coupled to photonic crystal cavity. We utilize combination nanolithographic techniques dopant-selective photoelectrochemical etch produce suspended cavities with quality factors exceeding 5000. Subsequent coupling leads factor ∼50,...
Inherent symmetry of a quantum system may protect its otherwise fragile states. Leveraging such protection requires testing robustness against uncontrolled environmental interactions. Using 47 superconducting qubits, we implement the one-dimensional kicked Ising model which exhibits non-local Majorana edge modes (MEMs) with $\mathbb{Z}_2$ parity symmetry. Remarkably, find that any multi-qubit Pauli operator overlapping MEMs uniform late-time decay rate comparable to single-qubit relaxation...
Systems of correlated particles appear in many fields modern science and represent some the most intractable computational problems nature. The challenge these systems arises when interactions become comparable to other energy scales, which makes state each particle depend on all particles1. lack general solutions for three-body problem acceptable theory strongly electrons shows that our understanding fades number or interaction strength increases. One hallmarks interacting is formation...
We demonstrate a high dynamic range Josephson parametric amplifier (JPA) in which the active nonlinear element is implemented using an array of rf-SQUIDs. The device matched to 50 Ω environment with Klopfenstein-taper impedance transformer and achieves bandwidth 250–300 MHz input saturation powers up −95 dBm at 20 dB gain. A 54-qubit Sycamore processor was used benchmark these devices, providing calibration for readout power, estimation added noise, platform comparison against standard...
We have developed a novel, all-electronic biosensor for opioids that consists of an engineered μ-opioid receptor protein, with high binding affinity opioids, chemically bonded to graphene field-effect transistor read out ligand binding. A variant the protein provided chemical recognition was computationally redesigned enhance its solubility and stability in aqueous environment. shadow mask process fabricate arrays hundreds transistors average mobility ∼1500 cm(2) V(-1) s(-1) yield exceeding...
Interfacing solid-state defect electron spins to other quantum systems is an ongoing challenge. The ground-state spin's weak coupling its environment not only bestows excellent coherence properties but also limits desired drive fields. excited-state orbitals of these electrons, however, can exhibit stronger phononic and electric Here, we demonstrate electrically driven coherent interference in the optical transition single, basally oriented divacancies commercially available 4H silicon...
Practical quantum computing will require error rates that are well below what is achievable with physical qubits. Quantum correction offers a path to algorithmically-relevant by encoding logical qubits within many qubits, where increasing the number of enhances protection against errors. However, introducing more also increases sources, so density errors must be sufficiently low in order for performance improve code size. Here, we report measurement qubit scaling across multiple sizes, and...
In situ transmission electron microscopy (TEM) electronic transport measurements in nanoscale systems have been previously confined to two-electrode configurations. Here, we use the focused beam of a TEM fabricate three-electrode geometry from continuous 2D material where third electrode operates as side gate field-effect transistor configuration. Specifically, demonstrate nanosculpting freestanding graphene sheets into nanoribbons (GNRs) with proximal gates, together resulting GNRs, whose...
Quantum error correction provides a path to reach practical quantum computing by combining multiple physical qubits into logical qubit, where the rate is suppressed exponentially as more are added. However, this exponential suppression only occurs if below critical threshold. In work, we present two surface code memories operating threshold: distance-7 and distance-5 integrated with real-time decoder. The of our larger memory factor $\Lambda$ = 2.14 $\pm$ 0.02 when increasing distance two,...
An important measure of the development quantum computing platforms has been simulation increasingly complex physical systems. Prior to fault-tolerant computing, robust error mitigation strategies are necessary continue this growth. Here, we study within seniority-zero electron pairing subspace, which affords both a computational stepping stone fully correlated model, and an opportunity validate recently introduced ``purification-based'' error-mitigation strategies. We compare performance...
This two-part article series provides a generalized description of the scattering geometry Bragg coherent diffraction imaging (BCDI) experiments, shear distortion effects inherent in 3D image obtained from presently used methods and strategies to mitigate this distortion. Part I starts fundamental considerations present general real-space coordinate transformation required correct shear, compact operator formulation that easily lends itself implementation with available software packages....
Leakage of quantum information out computational states into higher energy represents a major challenge in the pursuit error correction (QEC). In QEC circuit, leakage builds over time and spreads through multi-qubit interactions. This leads to correlated errors that degrade exponential suppression logical with scale, challenging feasibility as path towards fault-tolerant computation. Here, we demonstrate execution distance-3 surface code distance-21 bit-flip on Sycamore processor where is...
Abstract Measurement has a special role in quantum theory 1 : by collapsing the wavefunction it can enable phenomena such as teleportation 2 and thereby alter "arrow of time" that constrains unitary evolution. When integrated many-body dynamics, measurements lead to emergent patterns information space-time 3-10 go beyond established paradigms for characterizing phases, either or out equilibrium 11-13 . On present-day NISQ processors 14 , experimental realization this physics is challenging...
Understanding how interacting particles approach thermal equilibrium is a major challenge of quantum simulators. Unlocking the full potential such systems toward this goal requires flexible initial state preparation, precise time evolution, and extensive probes for final characterization. We present simulator comprising 69 superconducting qubits which supports both universal gates high-fidelity analog with performance beyond reach classical simulation in cross-entropy benchmarking...
Indistinguishability of particles is a fundamental principle quantum mechanics. For all elementary and quasiparticles observed to date - including fermions, bosons, Abelian anyons this guarantees that the braiding identical leaves system unchanged. However, in two spatial dimensions, an intriguing possibility exists: non-Abelian causes rotations space topologically degenerate wavefunctions. Hence, it can change observables without violating indistinguishability. Despite well developed...
Measurement has a special role in quantum theory: by collapsing the wavefunction it can enable phenomena such as teleportation and thereby alter "arrow of time" that constrains unitary evolution. When integrated many-body dynamics, measurements lead to emergent patterns information space-time go beyond established paradigms for characterizing phases, either or out equilibrium. On present-day NISQ processors, experimental realization this physics is challenging due noise, hardware...
Understanding universal aspects of quantum dynamics is an unresolved problem in statistical mechanics. In particular, the spin 1D Heisenberg model were conjectured to belong Kardar-Parisi-Zhang (KPZ) universality class based on scaling infinite-temperature spin-spin correlation function. a chain 46 superconducting qubits, we study probability distribution, $P(\mathcal{M})$, magnetization transferred across chain's center. The first two moments $P(\mathcal{M})$ show superdiffusive behavior,...