Mesoscale And Nanoscale Physics
Solid Lubrication with MoS
: A Review (1906.05854v1)
Mohammad R. Vazirisereshk, Ashlie Martini, David A. Strubbe, Mehmet Z. Baykara
2019-06-13
Molybdenum disulfide (MoS
Triggering InAs/GaAs Quantum Dot nucleation and growth rate determination by in-situ modulation of surface energy (1906.05842v1)
Peter Spencer, Chong Chen, Wladislaw Michailow, Harvey Beere, David Ritchie
2019-06-13
Epitaxial InAs/GaAs Quantum Dots (QDs) are widely used as highly efficient and pure sources of single photons and entangled photon-pairs, however reliable wafer-scale growth techniques have proved elusive. Growth of two-dimensional Quantum Well (QW) thin-films can be achieved with atomic precision down to below the de Broglie wavelength of electrons in the material, exposing the quantum particle-in-a-box energy vs. thickness-squared relationship. However, difficulties in controlling the exact moment of nanostructure nucleation obscure this behaviour in epitaxial QD material, preventing a clear understanding of their growth. In this work we demonstrate that QD nucleation can be induced by directly modulating the crystal surface energy without additional materials or equipment. This gains us quantitative measure of the QD growth rate and enables predictive design of QD growth processes. We believe this technique will be crucial to the realisation of uniform arrays of QDs required for scalable quantum devices at the single-photon level.
Hot Electron Dynamics in Plasmonic Thermionic Emitters (1905.01580v3)
Nicki Hogan, Shengxiang Wu, Matthew Sheldon
2019-05-05
Thermionic converters generate electricity from thermal energy in a power cycle based on vacuum emission of electrons. While thermodynamically efficient, practical implementations are limited by the extreme temperatures required for electron emission (> 1500 K). Here, we show how metal nanostructures that support resonant plasmonic absorption enable an alternative strategy. High electronic temperatures required for efficient vacuum emission can be maintained during steady-state optical absorption while the lattice temperature remains within the range of thermal stability, below 600 K. We have also developed an optical thermometry technique based on anti-Stokes Raman spectroscopy that confirms these unique electron dynamics. Thermionic devices constructed from plasmonic absorbers show performance that can out-compete other strategies of concentrated solar power conversion in terms of efficiency and thermal stability.
Crossed Andreev Reflection in InSb Flake Josephson Junctions (1906.05759v1)
Folkert K. de Vries, Martijn L. Sol, Sasa Gazibegovic, Roy L. M. op het Veld, Stijn C. Balk, Diana Car, Erik P. A. M. Bakkers, Leo P. Kouwenhoven, Jie Shen
2019-06-13
We study superconducting quantum interference in InSb flake Josephson junctions. An even-odd effect in the amplitude and periodicity of the superconducting quantum interference pattern is found. Interestingly, the occurrence of this pattern coincides with enhanced conduction at both edges of the flake, as is deduced from measuring a SQUID pattern at reduced gate voltages. We identify the specific crystal facet of the edge with enhanced conduction, and confirm this by measuring multiple devices. Furthermore, we argue the even-odd effect is due to crossed Andreev reflection, a process where a Cooper pair splits up over the two edges and recombines at the opposite contact. An entirely
periodic SQUID pattern, as well as the observation of both even-odd and odd-even effects, corroborates this conclusion. Crossed Andreev reflection could be harnessed for creating a topological state of matter or performing experiments on the non-local spin-entanglement of spatially separated Cooper pairs.
The Measurement of Near-Field Thermal Emission Spectra using an Infrared Waveguide (1810.09241v2)
Saman Zare, Carl Tripp, Sheila Edalatpour
2018-10-10
We describe a simple and robust method using an internal reflection element acting as an infrared waveguide to measure the spectra of near-field thermal emission. We experimentally demonstrate the spectrally-narrow peaks of near-field thermal emission by isotropic media due to the excitation of surface phonon-polaritons in quartz and amorphous silica and due to the frustrated total-internal-reflection modes in amorphous silica and polytetrafluoroethylene. Additionally, we demonstrate the broadband near-field thermal emission of hyperbolic modes in hexagonal boron nitride which is an anisotropic uniaxial medium. We also present a theoretical approach based on the fluctuational electrodynamics and dyadic Green's functions for one-dimensional layered media for accurate modeling of the measured spectra.
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