A5041875872- Quantum and electron transport phenomena
- Physics of Superconductivity and Magnetism
- Topological Materials and Phenomena
- High-pressure geophysics and materials
- Quantum Information and Cryptography
- Ion-surface interactions and analysis
- Graphene research and applications
- Photonic and Optical Devices
- Mechanical and Optical Resonators
- Diamond and Carbon-based Materials Research
- Laser-Plasma Interactions and Diagnostics
- Microstructure and mechanical properties
- Advanced Condensed Matter Physics
- Surface and Thin Film Phenomena
- Crystallography and Radiation Phenomena
- Semiconductor Quantum Structures and Devices
- Semiconductor Lasers and Optical Devices
- Advanced Surface Polishing Techniques
- Quantum Computing Algorithms and Architecture
- Nonlinear Optical Materials Research
- Sensor Technology and Measurement Systems
- Advanced MEMS and NEMS Technologies
- Electronic and Structural Properties of Oxides
- High-Velocity Impact and Material Behavior
- Magneto-Optical Properties and Applications
University of Chicago
2023-2025
Institute of Science and Technology Austria
2019-2025
University of Kansas Medical Center
2024
University of York
2017-2022
Microsoft (Denmark)
2019-2021
University of Copenhagen
2014-2021
University of Colorado Boulder
2017-2018
National Institute of Standards and Technology
2017-2018
Joint Institute for Laboratory Astrophysics
2016-2018
Harvard University
2014-2017
We introduce a scheme for preparation, manipulation, and readout of Majorana zero modes in semiconducting wires with mesoscopic superconducting islands. Our approach synthesizes recent advances materials growth tools commonly used quantum-dot experiments, including gate-control tunnel barriers Coulomb effects, charge sensing, pumping. outline sequence milestones interpolating between zero-mode detection quantum computing that includes (1) fusion rules non-Abelian anyons using either proximal...
The coexistence of gate-tunable superconducting, magnetic and topological orders in magic-angle twisted bilayer graphene provides opportunities for the creation hybrid Josephson junctions. Here we report fabrication gate-defined symmetry-broken junctions graphene, where weak link is gate-tuned close to correlated insulator state with a moiré filling factor υ = -2. We observe phase-shifted asymmetric Fraunhofer pattern pronounced hysteresis. Our theoretical calculations junction link-with...
The propagation of shock waves through polycrystalline iron is explored by large-scale atomistic simulations. For large enough strengths the passage wave causes body-centered-cubic phase to transform into a close-packed with most structure being isotropic hexagonal-close-packed (hcp) and, depending on strength and grain orientation, some fraction face-centered-cubic (fcc) structure. simulated Hugoniot compared experiments. By calculating extended x-ray absorption fine (EXAFS) directly from...
We investigate effects of quasiparticle poisoning in a Majorana island with strong tunnel coupling to normal-metal leads. In addition the main Coulomb blockade diamonds, "shadow" diamonds appear, shifted by 1e gate voltage, consistent transport through an excited (poisoned) state island. Comparison simple model yields estimate parity lifetime for strongly coupled (∼1 μs) and sets bound weakly (>10 μs). Fluctuations gate-voltage spacing peaks at high field, reflecting hybridization, are...
We present conductance-matrix measurements of a three-terminal superconductor-semiconductor hybrid device consisting two normal leads and one superconducting lead. Using symmetry decomposition the conductance, we find that antisymmetric components pairs local nonlocal conductances qualitatively match at energies below gap, compare this finding with relations based on noninteracting scattering matrix approach. Further, charge character Andreev bound states is extracted from...
Two-terminal conductance spectroscopy of superconducting devices is a common tool for probing Andreev and Majorana bound states. Here, we study theoretically three-terminal setup, with two normal leads coupled to grounded terminal. Using single-electron scattering matrix, derive the subgap matrix discuss its symmetries. In particular, show that local nonlocal elements have pairwise identical antisymmetric components. Moreover, find are directly related BCS charges states close probes how...
We build a parametric amplifier with Josephson field-effect transistor (JoFET) as the active element. The resonant frequency of device is tunable over range $2\phantom{\rule{0.2em}{0ex}}\mathrm{GHz}$. JoFET has $20\phantom{\rule{0.2em}{0ex}}\mathrm{dB}$ gain, $4\phantom{\rule{0.2em}{0ex}}\mathrm{MHz}$ instantaneous bandwidth, and 1-dB compression point $\ensuremath{-}125.5\phantom{\rule{0.2em}{0ex}}\mathrm{dBm}$ when operated at fixed resonance frequency.
Analysis of the results obtained from material simulations is important in physical sciences. Our research was motivated by need to investigate properties a simulated porous solid as it hit projectile. This paper describes two techniques for generation distance fields containing minimal number topological features, and we use them identify features material. We focus on defined volumetric domain considering given surface embedded within domain. Topological field are characterized its...
Conclusively identifying Majorana modes in nanowires is an long-standing experimental challenge. Within the field, consensus emerging that achieving this goal will require measurements on three-terminal devices. Here, authors report some of first results such devices using nonlocal conductance. They find zero-bias peaks are preceded by closure bulk gap, which indicates these associated with properties nanowire. However, behavior device after gap suggests disorder remains important limitation.
Despite a number of previous nonequilibrium molecular dynamics (MD) studies into plasticity in face-centered-cubic metals, and phase transitions body-centered-cubic (bcc) the plastic response to rapid compression bcc metals remains largely unexplored. Key questions remain as relative importance dislocation motion twinning shear stress release consequent strength. We present here large scale MD simulations shock compressed metal, using an extended Finnis-Sinclair potential for tantalum,...
Multielectron spin qubits are demonstrated, and performance examined by comparing coherent exchange oscillations in coupled single-electron multielectron quantum dots, measured the same device. Fast ($>1\text{ }\text{ }\mathrm{GHz}$) with a quality factor $Q\ensuremath{\sim}15$ found for case, compared to $Q\ensuremath{\sim}2$ latter consistent experiments literature. A model of dephasing that includes voltage hyperfine noise is developed good agreement both single- data, though cases...
Relaxation and dephasing of hole spins are measured in a gate-defined Ge/Si nanowire double quantum dot using fast pulsed-gate method dispersive readout. An inhomogeneous time $T_2^* \sim 0.18~\mathrm{\mu s}$ exceeds corresponding measurements III-V semiconductors by more than an order magnitude, as expected for predominately nuclear-spin-free materials. Dephasing is observed to be exponential time, indicating the presence broadband noise source, rather Gaussian, previously seen systems with...
The distribution of Coulomb blockade peak heights as a function magnetic field is investigated experimentally in Ge/Si nanowire quantum dot. Strong spin-orbit coupling this hole-gas system leads to antilocalization peaks, consistent with theory. In particular, the height has its maximum away from zero at field, an average that decreases increasing field. Magnetoconductance open-wire regime places bound on length (${l}_{\mathrm{so}}<20\text{ }\text{ }\mathrm{nm}$), values extracted...
Recent experiments have produced mounting evidence of Majorana zero modes in nanowire-superconductor hybrids. Signatures an expected topological phase transition accompanying the onset these nevertheless remain elusive. We investigate a fundamental question concerning this issue: Do well-formed necessarily entail sharp setups? Assuming reasonable parameters, we argue that finite-size effects can dramatically smooth putative into crossover, even systems large enough to support well-localized...
End-to-end correlated bound states are investigated in superconductor-semiconductor hybrid nanowires at zero magnetic field. Peaks subgap conductance independently identified from each wire end, and a cross-correlation function is computed that counts end-to-end coincidences, averaging over thousands of features. Strong correlations short, 300-nm device reduced by factor 4 long, 900-nm device. In addition, distributions investigated, between the left right based on their mutual information.
Superconductor-semiconductor hybrid devices are at the heart of several proposed approaches to quantum information processing, but their basic properties remain be understood. We embed a two-dimensional Al-InAs system in resonant microwave circuit, probing breakdown superconductivity due an applied magnetic field. find fingerprint from two-component nature system, and quantitatively compare with theory that includes contribution intraband p±ip pairing InAs, as well emergence Bogoliubov-Fermi...
By irradiating a thin metal foil with an intense short-pulse laser, we have created uniform system far from equilibrium. The deposited energy is initially only within the electronic subsystem, and subsequent evolution of determined by details electron-phonon coupling. Here, measure time lattice parameter through multilayer Bragg diffraction compare result to classical molecular dynamic simulations determine temperature. electron-ion coupling constant for gold then comparison two-temperature system.
Abstract Arrays of Josephson junctions are governed by a competition between superconductivity and repulsive Coulomb interactions, expected to exhibit diverging low-temperature resistance when interactions exceed critical level. Here we report study the transport microwave response arrays with exceeding this Contrary expectations, observe that array drops dramatically as temperature is decreased—reminiscent superconducting behaviour—and then saturates at low temperature. Applying magnetic...