Semiconductor nanowire (NW) quantum devices offer a promising path for the pursuit and investigation of topologically-protected quantum states, and superconducting and spin-based qubits that can be controlled using electric fields. Theoretical investigations into the impact of disorder on the attainment of dependable topological states in semiconducting nanowires with large spin–orbit coupling and
Realizing a large Landé
- Award ID(s):
- 1809120
- NSF-PAR ID:
- 10373678
- Publisher / Repository:
- Nature Publishing Group
- Date Published:
- Journal Name:
- Nature Communications
- Volume:
- 13
- Issue:
- 1
- ISSN:
- 2041-1723
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
More Like this
-
Abstract g -factor highlight the critical need for improvements in both growth processes and nanofabrication techniques. In this work, we used a hybrid lithography tool for both the high-resolution thermal scanning probe lithography and high-throughput direct laser writing of quantum devices based on thin InSb nanowires with contact spacing of 200 nm. Electrical characterization demonstrates quasi-ballistic transport. The methodology outlined in this study has the potential to reduce the impact of disorder caused by fabrication processes in quantum devices based on 1D semiconductors. -
Abstract Quantum devices based on InSb nanowires (NWs) are a prime candidate system for realizing and exploring topologically-protected quantum states and for electrically-controlled spin-based qubits. The influence of disorder on achieving reliable quantum transport regimes has been studied theoretically, highlighting the importance of optimizing both growth and nanofabrication. In this work, we consider both aspects. We developed InSb NW with thin diameters, as well as a novel gating approach, involving few-layer graphene and atomic layer deposition-grown AlO
x . Low-temperature electronic transport measurements of these devices reveal conductance plateaus and Fabry–Pérot interference, evidencing phase-coherent transport in the regime of few quantum modes. The approaches developed in this work could help mitigate the role of material and fabrication-induced disorder in semiconductor-based quantum devices. -
Abstract In the recently discovered kagome metal CsV3Sb5, an intriguing proposal invoking a doped Chern insulator state suggests the presence of small Chern Fermi pockets hosting spontaneous orbital-currents and large orbital magnetic moments. While the net thermodynamic magnetization is nearly insensitive to these moments, due to their antiferromagnetic alignment, their presence can be revealed by the Zeeman effect, which shifts electron energies in magnetic fields with a proportionality given by the effective
g −factor. Here, we determine theg -factor using the spin-zero effect in magnetic quantum oscillations. A largeg -factor enhancement is visible only in magnetic breakdown orbits between conventional and concentrated Berry curvature Fermi pockets that host large orbital moments. Such Berry-curvature-generated large orbital moments are almost always concealed by other effects. In this system, however, magnetic breakdown orbits due to the proximity to a conventional Fermi-surface section allow them to be visibly manifested in magnetic quantum oscillations. Our results provide a remarkable example of the interplay between electronic correlations and more conventional electronic bands in quantum materials. -
Abstract The electronic structure of surfaces plays a key role in the properties of quantum devices. However, surfaces are also the most challenging to simulate and engineer. Here, the electronic structure of InAs(001), InAs(111), and InSb(110) surfaces is studied using a combination of density functional theory (DFT) and angle‐resolved photoemission spectroscopy (ARPES). Large‐scale first principles simulations are enabled by using DFT calculations with a machine‐learned Hubbard U correction [npj Comput. Mater. 6, 180 (2020)]. To facilitate direct comparison with ARPES results, a “bulk unfolding” scheme is implemented by projecting the calculated band structure of a supercell surface slab model onto the bulk primitive cell. For all three surfaces, a good agreement is found between DFT calculations and ARPES. For InAs(001), the simulations clarify the effect of the surface reconstruction. Different reconstructions are found to produce distinctive surface states, which may be detected by ARPES with low photon energies. For InAs(111) and InSb(110), the simulations help elucidate the effect of oxidation. Owing to larger charge transfer from As to O than from Sb to O, oxidation of InAs(111) leads to significant band bending and produces an electron pocket, whereas oxidation of InSb(110) does not. The combined theoretical and experimental results may inform the design of quantum devices based on InAs and InSb semiconductors, for example, topological qubits utilizing the Majorana zero modes.
-
Abstract Fӧrster (or fluorescence) resonance energy transfer (FRET) is a quantifiable energy transfer in which a donor fluorophore nonradiatively transfers its excitation energy to an acceptor fluorophore. A change in FRET efficiency indicates a change of proximity and environment of these fluorophores, which enables the study of intermolecular interactions. Measurement of FRET efficiency using the sensitized emission method requires a donor–acceptor calibrated system. One of these calibration factors named the
G factor, which depends on instrument parameters related to the donor and acceptor measurement channels and on the fluorophores quantum efficiencies, can be determined in several different ways and allows for conversion of the raw donor and acceptor emission signals to FRET efficiency. However, the calculated value of the G factor from experimental data can fluctuate significantly depending on the chosen experimental method and the size of the sample. In this technical note, we extend the results of Gates et al. (Cytometry Part A 95A (2018) 201–213) by refining the calibration method used for calibration of FRET from image pixel data. Instead of using the pixel histograms of two constructs with high and low FRET efficiency to determine theG factor, we use pixel histogram data from one construct of known efficiency. We validate this method by determining theG factor with the same constructs developed and used by Gates et al. and comparing the results from the two approaches. While the two approaches are equivalent theoretically, we demonstrate that the use of a single construct with known efficiency provides a more precise experimental measurement of theG factor that can be attained by collecting a smaller number of images. © 2020 International Society for Advancement of Cytometry