A5022971792- Quantum and electron transport phenomena
- Physics of Superconductivity and Magnetism
- Topological Materials and Phenomena
- Electronic and Structural Properties of Oxides
- Semiconductor Quantum Structures and Devices
- Molecular Junctions and Nanostructures
- Magnetic properties of thin films
- Quantum optics and atomic interactions
- Advancements in Semiconductor Devices and Circuit Design
- Quantum Computing Algorithms and Architecture
- Quantum many-body systems
- Ferroelectric and Negative Capacitance Devices
- Semiconductor materials and devices
- Neural Networks and Reservoir Computing
- Surface and Thin Film Phenomena
- Quantum Information and Cryptography
Fermi National Accelerator Laboratory
2023
University of Copenhagen
2019-2023
Microsoft (Denmark)
2019-2021
Institut polytechnique de Grenoble
2020
Université Grenoble Alpes
2015-2020
Centre National de la Recherche Scientifique
2015-2020
Institut Néel
2016-2020
We present a gate-voltage tunable transmon qubit (gatemon) based on planar InAs nanowires that are selectively grown high resistivity silicon substrate using III-V buffer layers. show low loss superconducting resonators with an internal quality of $2\times 10^5$ can readily be realized these substrates after the removal demonstrate coherent control and readout gatemon device relaxation time, $T_{1}\approx 700\,\mathrm{ns}$, dephasing times, $T_2^{\ast}\approx 20\,\mathrm{ns}$...
We report on the realization of a single-electron source, where current is transported through single-level quantum dot (Q) tunnel coupled to two superconducting leads (S). When driven with an ac gate voltage, experiment demonstrates electron turnstile operation. Compared more conventional superconductor-normal-metal-superconductor turnstile, our superconductor-quantum-dot-superconductor device presents number novel properties, including higher immunity unavoidable presence nonequilibrium...
Quantum information science harnesses the principles of quantum mechanics to realize computational algorithms with complexities vastly intractable by current computer platforms. Typical applications range from chemistry optimization problems and also include simulations for high energy physics. The recent maturing hardware has triggered preliminary explorations several institutions (including Fermilab) capable demonstrating advantage in multiple domains, computing communications, sensing....
Radio-frequency (RF) reflectometry is implemented in hybrid semiconductor-superconductor nanowire systems designed to probe Majorana zero modes. Two approaches are presented. In the first, nanowire-based devices part of a resonant circuit, allowing conductance be measured as function several gate voltages ~40 times faster than using conventional low-frequency lock-in methods. second, capacitively coupled nearby RF single-electron transistor made from separate nanowire, detection charge,...
The performance of superconducting devices is often degraded by the uncontrolled appearance and disappearance quasiparticles, a process known as poisoning. We demonstrate electrostatic control quasiparticle poisoning in form single-charge tunneling across fixed barrier onto Coulomb island an InAs/Al hybrid nanowire. High-bandwidth charge sensing was used to monitor occupancy blockade peaks, where rates were maximal, valleys, absent. Electrostatic gates changed on-peak two orders magnitude...
Dispersive charge sensing is realized in hybrid semiconductor-superconductor nanowires gate-defined single- and double-island device geometries. Signal-to-noise ratios (SNRs) were measured both the frequency time domains. Frequency-domain measurements carried out as a function of power yield sensitivity 1 × 10–3 e/Hz for an ∼11 MHz measurement bandwidth. Time-domain SNR > 20 μs integration time. At zero magnetic field, photon-assisted tunneling was detected dispersively geometry,...
Electron transport through a quantum dot coupled to superconducting leads shows sharp conductance onset when orbital level crosses the coherence peak of one lead. We study single electron transistors in weak coupling limit by connecting individual gold nanoparticles with aluminum formed electromigration. show that features close threshold can be accurately described levels' hybridization leads, which is strongly enhanced divergent density states at gap edge. This highlights importance...
The magnetic moment of a quantum dot can be screened by its coupling to superconducting reservoir, depending on the hierarchy gap and relevant Kondo scale. This screening-unscreening transition driven electrostatic gating, tunnel coupling, and, as we demonstrate here, field. We perform high-resolution spectroscopy subgap excitations near asymmetric superconductor - (S-QD-S) junctions formed electromigration technique. Our measurements reveal re-entrant phase boundary determined competition...
We present a superconductor-semiconductor materials system that is both scalable and monolithically integrated on silicon substrate. It uses selective-area growth of $\mathrm{Al}$-$\mathrm{In}\mathrm{As}$ hybrid structures planar III-V buffer layer, grown directly high-resistivity characterize the electrical properties this at millikelvin temperatures observe high average field-effect mobility $\ensuremath{\mu}\ensuremath{\approx}3200\phantom{\rule{0.2em}{0ex}}{\mathrm{cm}}^{2}\mathrm{/Vs}$...
We present a gate-voltage tunable transmon qubit (gatemon) based on planar InAs nanowires that are selectively grown high resistivity silicon substrate using III-V buffer layers. show low loss superconducting resonators with an internal quality of $2\times 10^5$ can readily be realized these substrates after the removal demonstrate coherent control and readout gatemon device relaxation time, $T_{1}\approx 700\,\mathrm{ns}$, dephasing times, $T_2^{\ast}\approx 20\,\mathrm{ns}$...
Using a spin-polarized muon beam we were able to capture magnetic dynamics in an amorphous niobium pentoxide thin film. Muons are used probe internal fields produced by defects. Magnetic fluctuations could be described the dynamical Kubo-Toyabe model considering time-dependent local field. We state that observed result from correlated motion of electron spins. expect oxygen vacancies play significant role these films and lead complex field distribution which is non-stationary. The...
The performance of superconducting devices is often degraded by the uncontrolled appearance and disappearance quasiparticles, a process known as poisoning. We demonstrate electrostatic control quasiparticle poisoning in form single-charge tunneling across fixed barrier onto Coulomb island an InAs/Al hybrid nanowire. High-bandwidth charge sensing was used to monitor occupancy blockade peaks, where rates were maximal, valleys, absent. Electrostatic gates changed on-peak two orders magnitude...