Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session L62: Electron Transport in Nanostructures IFocus
|
Hide Abstracts |
Sponsoring Units: DMP Chair: Jia Li, Brown University Room: Mile High Ballroom 4C |
Wednesday, March 4, 2020 8:00AM - 8:36AM |
L62.00001: Ultrafast and Cooperative Light-Matter Coupling Invited Speaker: Junichiro Kono Recent experiments have shown that light and matter can mix together to an extreme degree, entering previously uncharted regimes of light-matter interactions [1]. This talk will summarize a series of experiments we have performed in such regimes. We will first describe our observation of ultrastrong coupling (USC) of a 2D electron gas with high-Q THz cavity photons in a quantizing magnetic field, demonstrating a record-high cooperativity [2]. The electron cyclotron resonance peak exhibited splitting into the lower and upper polariton branches with a magnitude that is proportional to the square-root of the electron density, a hallmark of cooperative vacuum Rabi splitting (VRS), known as Dicke cooperativity. Additionally, we have obtained evidence for the vacuum Bloch-Siegert shift [3], a signature of the breakdown of the rotating-wave approximation. The second part of this talk will present microcavity exciton polaritons in a thin film of aligned carbon nanotubes [4] embedded in a Fabry-Pérot cavity. This system exhibited cooperative USC with unusual continuous controllability over the coupling strength through polarization rotation [5]. Finally, we have generalized the concept of Dicke cooperativity to show that it also occurs in a magnetic solid in the form of matter-matter interaction [6]. Specifically, the exchange interaction of N paramagnetic Er3+ spins with an Fe3+ magnon field in ErFeO3 exhibited a VRS whose magnitude is proportional to N1/2. Our results provide a route for understanding, controlling, and predicting novel phases of condensed matter using concepts and tools available in quantum optics. 1. P. Forn-Díaz, L. Lamata, E. Rico, J. Kono, and E. Solano, Revi. Mod. Phys. 91, 025005 (2019). 2. Q. Zhang et al., Nat. Phys. 12, 1005 (2016). 3. X. Li et al., Nat. Photon. 12, 324 (2018). 4. X. He et al., Nat. Nanotechnol. 11, 633 (2016). 5. W. Gao et al., Nat. Photon. 12, 362 (2018). 6. X. Li et al., Science 361, 794 (2018). |
Wednesday, March 4, 2020 8:36AM - 8:48AM |
L62.00002: Anomalous Dirac Plasmons in 1D Topological Electrides Jianfeng Wang, Xuelei Sui, Shiwu Gao, Wenhui Duan, Feng Liu, Bing Huang Plasmon opens up the possibility to efficiently couple light and matter at sub-wavelength scales. In general, the plasmon frequency, intensity and damping are dependent of carrier density. These dependencies, however, are disadvantageous for stable functionalities of plasmons and render fundamentally a weak intensity at low frequency, especially for Dirac plasmon (DP) widely studied in graphene. Here we demonstrate a new type of DP, emerged from a Dirac nodal-surface state, which can simultaneously exhibit density-independent frequency, intensity and damping. Remarkably, we predict realization of anomalous DP (ADP) in 1D topological electrides, such as Ba3CrN3 and Sr3CrN3, by first-principles calculations. The ADPs in both systems have density-independent frequency and high intensity, and their frequency can be tuned from terahertz to mid-infrared by changing the excitation direction. Furthermore, the intrinsic weak electron-phonon coupling of anionic electrons in electrides affords an added advantage of low phonon-assisted damping and hence a long lifetime of the ADPs. Our work paves the way to developing novel plasmonic and optoelectronic devices by combining topological physics with electride materials. |
Wednesday, March 4, 2020 8:48AM - 9:00AM |
L62.00003: Ultrafast terahertz microscopy down to the atomic scale Tyler Cocker, Spencer Ammerman, Vedran Jelic, Nicholas J Breslin Recent developments have allowed terahertz (THz) scanning probe microscopy to achieve unprecedented simultaneous temporal and spatial resolutions. Included in the arsenal of THz microscopy techniques are terahertz scanning tunneling microscopy (THz-STM), which reveals the ultrafast response of a tunnel junction with atomic resolution [1-3], scattering-type scanning near-field optical microscopy (s-SNOM), which reveals the local dielectric function [4-6], and terahertz emission nanoscopy, which reveals local contrast in THz fields generated at the sample surface [7,8]. In this talk I will show examples of the types of experiments that can be done with each technique, including atomically resolved THz-STM snapshot imaging of local electron densities. |
Wednesday, March 4, 2020 9:00AM - 9:12AM |
L62.00004: Boltzmann treatment of nanoscale inhomogeneous electrical conduction Ryan Mescall, Philip Allen Small distance scales (e.g. boundaries of small samples) destroy the propagating electron quasiparticles that Boltzmann transport theory needs. Our model retains propagating single particle electrons, but generates nanoscale inhomogeneities by introducing nanoscale source terms In the Boltzmann equation of a macroscopic homogeneous metal. We solve the equations in Fourier space for electron distribution functions arising from charge input ~exp(iqx). Fourier transformation allows computation of fields the E(x), V(x), and n(x) corresponding to currents j(x) derived from a realistic charge input from discrete electrodes. We study the ballistic to diffusive crossover as the sample size and electrode size are varied on distance scales comparable to the electron mean free path. |
Wednesday, March 4, 2020 9:12AM - 9:24AM |
L62.00005: Hydrodynamic effects of ballistic electron jets in high-mobility GaAs/AlGaAs Adbhut Gupta, Jean J Heremans, Saeed Fallahi, Geoff C Gardner, Michael Manfra The influence of a ballistic electron jet, injected through a lithographic aperture, |
Wednesday, March 4, 2020 9:24AM - 9:36AM |
L62.00006: On the Nonphysical Solutions to the Wigner Equation Used in Electronic Transport Makbule Kubra Eryilmaz, Sina Soleimanikahnoj, Irena Knezevic The Wigner transport equation is gaining traction as a useful tool for modeling quantum electronic transport in semiconductors. However, nonphysical results are known to occur in numerical implementations and are often related to violation of the Heisenberg uncertainty principle when finite-difference techniques are employed. In this study, we analyze the role of boundary conditions in the behavior of the solutions to the Wigner equation for the example of a finite-sized one-dimensional nanostructure with a potential barrier in the middle and connected to reservoirs of charge. We discuss the cases in which artefacts occur and propose a boundary condition scheme that alleviates potential issues stemming from charge injection into a finite-sized simulation domain. |
Wednesday, March 4, 2020 9:36AM - 9:48AM |
L62.00007: Quantum-dot–insulator–superconductor junctions coupled to a microwave resonator Vasilii Sevriuk, Matti Silveri, Mikko Mottonen Quantum dots are finding more and more important applications in the modern electronics. Recent works related to the electron tunneling between a quantum dot and superconducting lead [1,2] inspired us to theoretically study the system consisting of quantum-dot–insulator–superconductor (QIS) junctions coupled to the microwave resonator. For this purpose, we adapted the theory developed before for the so-called quantum-circuit refrigerator [3-6], which is based on normal-metal–insulator–superconductor junctions. We demonstrate that the current running through the QIS junctions can lead to a negative damping rate at the microwave resonator and discuss the possibility to use such a system as a narrow-band amplifier and a microwave laser. |
Wednesday, March 4, 2020 9:48AM - 10:00AM |
L62.00008: Multiple perfectly transmitting states of a discrete level at strong coupling Étienne Jussiau, Robert S. Whitney, Andrew N Jordan We analyze the transport properties of a discrete level between two reservoirs with a band structure. We focus on the case where the level is strongly coupled to the reservoirs, the coupling parameter is typically of the order of the energy scales of the band structures. In the absence of interactions, this system has an exact solution and the nonlinear Lamb shift can be derived. As expected, the Lamb shift has the effect of pushing the perfectly transmitting state (the reservoir state that flows through the discrete level without reflection) out of resonance with the discrete level, and can possibly turn it into a bound state. However, we show that additional pairs of perfectly transmitting states may appear due to the nonlinear Lamb shift when the coupling exceeds a critical value. The transmission function of the discrete level then resembles that of a multi-level system. Even in situations where the energy of the discrete level is outside the reservoirs' band, a perfectly transmitting state can be created inside the band if the coupling is strong enough. We propose observing the bosonic version of this physics in microwave cavities, and the fermionic version in the conductance of a quantum dot coupled to 1D or 2D reservoirs. |
Wednesday, March 4, 2020 10:00AM - 10:12AM |
L62.00009: Development of single-electron and single-electron-pair sources in LaAlO3/SrTiO3 nanostructures Yang Hu, Yuhe Tang, Dengyu Yang, Yun-Yi Pai, Jianan Li, Hyungwoo Lee, Jung-Woo Lee, Chang-Beom Eom, Patrick Irvin, Jeremy Levy A source of single electrons can be realized by coupling quantum dots with tunnel barriers [1]. The 2D electron gas at the LaAlO3/SrTiO3 interface can be patterned using conductive atomic force microscope (c-AFM) lithography [2], which has been used to create quantum dots and single electron transistors [3]. We aim to use this technique to create an on-demand single-electron source by sketching quantum dots and applying out-of-phase excitation across the dot array. We discuss results for a triple-dot device and their associated electron tunneling phenomenon and issues related to the individual tunabilities of the dots. These devices may have application to quantum computation and simulation, and could also provide a robust standard for the electric unit ampere. |
Wednesday, March 4, 2020 10:12AM - 10:24AM |
L62.00010: Electron transfer in thermally heterogeneous environments Galen Craven, Abraham Nitzan Electron transfer is a fundamental process that drives many physical, chemical, and biological transformations, as well as playing a ubiquitous role in the development of electronics and technologies for energy conversion. Recent advances in temperature measurement and control at the nanoscale allow thermal gradients and heat flow to be addressed at the molecular level, making it possible to observe electron transfer across thermal gradients. In this talk, I will discuss the development of a theoretical framework to describe electron transfer between donor and acceptor sites, where each site has a different local temperature. The transfer of charge across the resulting thermal gradient is found to be coupled with an energy transfer mechanism that may alter heat conduction between sites. Application of the developed theory suggests that emergent relations connecting thermal and electronic currents can be utilized to control energy conversion between redox molecular motifs, at molecule-metal interfaces, and in molecular junctions. |
Wednesday, March 4, 2020 10:24AM - 10:36AM |
L62.00011: Suppression of ballistic effects in the ultra-pure delafossite PtCoO2 via high-energy electron irradiation Philippa McGuinness, Elina Zhakina, Veronika Sunko, Marcin Konczykowski, Seunghyun Khim, Markus Koenig, Andrew Mackenzie PtCoO2 is a layered oxide delafossite material which has a hexagonal, single-band Fermi surface. This ultrapure metal is extremely conductive, with a low-temperature mean free path of up to 5 μm [1]. Due to these properties, novel low-temperature ballistic effects have been demonstrated in the magnetoresistance of micron-scale ultrapure delafossite devices [2]. To determine the sensitivity of the ballistic behavior to disorder, we have used 2.5 MeV electron irradiation to introduce point-defect impurities into PtCoO2 microstructures. This reduces the mean free path and therefore suppresses the ballistic phenomena. Surprisingly, these effects remain, in a weaker form, at an impurity level significantly higher than would be expected from the usual limits of the ballistic regime. |
Wednesday, March 4, 2020 10:36AM - 10:48AM |
L62.00012: Single electron occupation in a bilayer graphene double quantum dot Christian Volk, Luca Banszerus, Samuel Möller, Eike Icking, Kenji Watanabe, Takashi Taniguchi, Christoph Stampfer Graphene quantum dots (QDs) are an attractive platform for hosting spin qubits since the low nuclear spin densities and weak spin-orbit interaction in graphene promise long spin coherence times. Physically etched graphene QDs have been studied for about a decade. However, the influence of disorder, in particular the edge disorder prevented a precise control of the number of confined charge carriers. |
Wednesday, March 4, 2020 10:48AM - 11:00AM |
L62.00013: Coulomb drag between a carbon nanotube and monolayer graphene Samvel Badalyan, Antti-Pekka Jauho We study Coulomb drag in a system consisting of a carbon nanotube and monolayer graphene. Within the Fermi liquid theory we calculate the drag resistivity and find that the dimensional mismatch of the system components leads to a dependence of the drag rate on the carrier density, temperature, and spacing, which is substantially different from what is known for graphene double layers. We identify new features of the drag dependence on the electron density, which allows us to control their relative contribution to the drag resistivity. |
Follow Us |
Engage
Become an APS Member |
My APS
Renew Membership |
Information for |
About APSThe American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics. |
© 2024 American Physical Society
| All rights reserved | Terms of Use
| Contact Us
Headquarters
1 Physics Ellipse, College Park, MD 20740-3844
(301) 209-3200
Editorial Office
100 Motor Pkwy, Suite 110, Hauppauge, NY 11788
(631) 591-4000
Office of Public Affairs
529 14th St NW, Suite 1050, Washington, D.C. 20045-2001
(202) 662-8700