On the stability of discontinuous solutions of bilinear systems with impulse action, constant and linear delays

This paper is devoted to the study of the stability properties of solutions bilinear system of differential equations with generalized effects in the system matrix, constant and linear delays in phase coordinates. Sufficient stability conditions are obtained. © 2019 Author(s).Russian Foundation for Basic Research, RFBR: 19-01-00371The research was supported by Russian Foundation for Basic Research, project no. 19-01-00371 and by Act 211 Government of the Russian Federation, contract 02.A03.21.0006

Band alignment at interfaces of synthetic few-monolayer MoS2 with SiO2 from internal photoemission

Electron band alignment at interfaces of SiO2 with directly synthesized few-monolayer (ML) thin semiconducting MoS2 films is characterized by using field-dependent internal photoemission of electrons from the valence band of MoS2 into the oxide conduction band. We found that reducing the grown MoS2 film thickness from 3 ML to 1 ML leads to ≈400 meV downshift of the valence band top edge as referenced to the common energy level of the SiO2 conduction band bottom. Furthermore, comparison of the MoS2 layers grown by a H-free process (sputtering of Mo in sulfur vapor) to films synthesized by sulfurization of metallic Mo in H2S indicates a significant (≈500 meV) electron barrier increase in the last case. This effect is tentatively ascribed to the formation of an interface dipole due to the interaction of hydrogen with the oxide surface

Quantum metrology with a transmon qutrit

Making use of coherence and entanglement as metrological quantum resources allows us to improve the measurement precision from the shot-noise or quantum limit to the Heisenberg limit. Quantum metrology then relies on the availability of quantum engineered systems that involve controllable quantum degrees of freedom which are sensitive to the measured quantity. Sensors operating in the qubit mode and exploiting their coherence in a phase-sensitive measurement have been shown to approach the Heisenberg scaling in precision. Here, we show that this result can be further improved by operating the quantum sensor in the qudit mode, i.e., by exploiting d rather than two levels. Specifically, we describe the metrological algorithm for using a superconducting transmon device operating in a qutrit mode as a magnetometer. The algorithm is based on the base-3 semiquantum Fourier transformation and enhances the quantum theoretical performance of the sensor by a factor of 2. Even more, the practical gain of our qutrit implementation is found in a reduction of the number of iteration steps of the quantum Fourier transformation by the factor ln(2)/ln(3)≈0.63 compared to the qubit mode. We show that a two-tone capacitively coupled radio-frequency signal is sufficient for implementation of the algorithm.Peer reviewe

Atomistic Investigation of the Electronic Structure, Thermal Properties and Conduction Defects in Ge-rich GexSe1-x Materials for Selector Applications

status: publishe

Internal photoemission of electrons from 2D semiconductor/3D metal barrier structures

Understanding the energy alignment of electronic bands, which originate from ultrathin MoS2 layers and metal electrodes attached to them, is crucial for the design of MoS2-based electronic devices. We have applied internal photoemission spectroscopy (IPE) to analyze this alignment. We demonstrate that IPE can yield the barrier heights in the metal/two-dimensional semiconductor/insulator stacks when the top metal electrode is sufficiently thin for allowing both the photoexcitation of electrons and their transport towards the insulator. The electron barrier at the interface between Al and monolayer (1ML) of MoS2 is estimated at 0.7 eV, and this value explains the experimentally observed attenuated quantum yield contribution from the aluminum. Based on the relative energies of the low-energy threshold position and the Fermi level of aluminum at the interface with the SiO2 insulator, we provide a simple explanation for the observed current photoinjection at the interface between aluminum and 1ML MoS2