Physics Commons^™

Room Temperature Tunneling Switches And Methods Of Making And Using The Same, Yoke Khin Yap

Michigan Tech Patents

The tunneling channel of a field effect transistor comprising a plurality of tunneling elements contacting a channel substrate. Applying a source-drain voltage of greater than a turn-on voltage produces a source-drain current of greater than about 10 pA. Applying a source-drain voltage of less than a turn-on voltage produces a source-drain current of less than about 10 pA. The turn-on voltage at room temperature is between about 0.1V and about 40V.

Global Association Of Aerosol With Flash Density Of Intense Lightning, Orit Altaratz, Beata Kucienska, Alexander Kostinski, Graciela B. Raga, Ilan Koren

Department of Physics Publications

A global scale study of the association between aerosol loading and lightning production was conducted, using a full year’s data for 2012 (as well as seasonal data) of the cloud-to-ground lightning record from the world wide lightning location network and aerosol optical depth measured by MODIS. 70% of all grid squares examined and 94% of the statistically significant ones had higher flash densities under polluted conditions than the clean ones. This trend is evident for large continental regions in North, Central and South America, Europe, southern Africa and north-east Australia. A detailed examination of the link to the meteorology was …

Eureka! Discovering A New Mineral: Meralaniite, John A. Jaszczak

TechTalks

A series of serendipitous events and four years of collaborative research has led to the discovery and description of a new mineral- merelaniite. It is a natural nanocomposite composed primarily of MoS2 and PbS layers from the famous tanzanite gem mines in northern Tanzania. It's crystal structure and chemistry is unusual and complex, and forms unusual silvery, scroll-like whiskers. It was selected by the International Mineralogical Association as the 2016 Mineral of the Year.

Modelling Parallel Overhead From Simple Run-Time Records, Siegfried Höfinger, Ernst Haunschmid

Michigan Tech Publications

A number of scientific applications run on current HPC systems would benefit from an approximate assessment of parallel overhead. In many instances a quick and simple method to obtain a general overview on the subject is regarded useful auxiliary information by the routine HPC user. Here we present such a method using just execution times for increasing numbers of parallel processing cores. We start out with several common scientific applications and measure the fraction of time spent in MPI communication. Forming the ratio of MPI time to overall execution time we obtain a smooth curve that can be parameterized by …

Robustness And Mode Selectivity In Parity-Time (Pt) Symmetric Lasers, M. H. Teimourpour, M. Khajavikhan, Demetrios N. Christodoulides, Ramy El-Ganainy

Department of Physics Publications

We investigate two important aspects of PT symmetric photonic molecule lasers, namely the robustness of their single longitudinal mode operation against instabilities triggered by spectral hole burning effects, and the possibility of more versatile mode selectivity. Our results, supported by numerically integrating the nonlinear rate equations and performing linear stability analysis, reveals the following: (1) In principle a second threshold exists after which single mode operation becomes unstable, signaling multimode oscillatory dynamics, (2) For a wide range of design parameters, single mode operation of PT lasers having relatively large free spectral range (FSR) can be robust even at higher gain …

Effect Of Thermodenuding On The Structure Of Nascent Flame Soot Aggregates, Janarjan Bhandari, Swarup China, Timothy Onasch, Lindsay Wolff, Andrew Lambe, Paul Davidovits, Claudio Mazzoleni, Et Al.

Michigan Tech Publications

The optical properties (absorption and scattering) of soot particles depend on soot size and index of refraction, but also on the soot complex morphology and the internal mixing with materials that can condense on a freshly emitted (nascent) soot particle and coat it. This coating can affect the soot optical properties by refracting light, or by changing the soot aggregate structure. A common approach to studying the effect of coating on soot optical properties is to measure the absorption and scattering coefficients in ambient air, and then measure them again after removing the coating using a thermodenuder. In this approach, …

Cloud Droplets To Drizzle: Contribution Of Transition Drops To Microphysical And Optical Properties Of Marine Stratocumulus Clouds, S Glienke, A. Kostinski, J P. Fugal, R. A. Shaw, S Borrmann, J Stith

Department of Physics Publications

Aircraft measurements of the ubiquitous marine stratocumulus cloud type, with over 3000 km of in situ data from the Pacific during the Cloud System Evolution in the Trades experiment, show the ability of the Holographic Detector for Clouds (HOLODEC) instrument to smoothly interpolate the small and large droplet data collected with Cloud Droplet Probe and 2DC instruments. The combined, comprehensive instrument suite reveals a surprisingly large contribution in the predrizzle size range of 40–80 μm (transition droplets, or drizzlets), a range typically not measured and assumed to reside in a condensation‐to‐collision minimum between cloud droplet and drizzle modes. Besides shedding …

Two-Dimensional Electronics And Optoelectronics: Present And Future, Zhixian Zhou, Yoke Khin Yap

Department of Physics Publications

Since the successful isolation of graphene a little over a decade ago, a wide variety of two-dimensional (2D) layered materials have been studied. They cover a broad spectrum of electronic properties, including metals, semimetals, semiconductors, and insulators. Many of these 2D materials have demonstrated promising potential for electronic and optoelectronic applications.

Non-Hermitian Matter-Wave Mixing In Bose-Einstein Condensates: Dissipation-Induced Amplification, S. Wuster, Ramy El-Ganainy

Department of Physics Publications

We investigate the nonlinear scattering dynamics in interacting atomic Bose-Einstein condensates under non-Hermitian dissipative conditions. We show that, by carefully engineering a momentum-dependent atomic loss profile, one can achieve matter-wave amplification through four-wave mixing in a quasi-one-dimensional nearly-free-space setup—a process that is forbidden in the counterpart Hermitian systems due to energy mismatch. Additionally, we show that similar effects lead to rich nonlinear dynamics in higher dimensions. Finally, we propose a physical realization for selectively tailoring the momentum-dependent atomic dissipation. Our strategy is based on a two-step process: (i) exciting atoms to narrow Rydberg or metastable excited states, and (ii) introducing …

Recent Advances In Electronic And Optoelectronic Devices Based On Two-Dimensional Transition Metal Dichalcogenides, Mingxiao Ye, Dongyan Zhang, Yoke Khin Yap

Department of Physics Publications

Two-dimensional transition metal dichalcogenides (2D TMDCs) offer several attractive features for use in next-generation electronic and optoelectronic devices. Device applications of TMDCs have gained much research interest, and significant advancement has been recorded. In this review, the overall research advancement in electronic and optoelectronic devices based on TMDCs are summarized and discussed. In particular, we focus on evaluating field effect transistors (FETs), photovoltaic cells, light-emitting diodes (LEDs), photodetectors, lasers, and integrated circuits (ICs) using TMDCs.

Terrestrial Glint Seen From Deep Space: Oriented Ice Crystals Detected From The Lagrangian Point, Alexander Marshak, Tamas Varnai, Alexander Kostinski

Department of Physics Publications

The Deep Space Climate Observatory (DSCOVR) spacecraft resides at the first Lagrangian point about one million miles from Earth. A polychromatic imaging camera onboard delivers nearly hourly observations of the entire sunlit face of the Earth. Many images contain unexpected bright flashes of light over both ocean and land. We construct a yearlong time series of flash latitudes, scattering angles, and oxygen absorption to demonstrate conclusively that the flashes over land are specular reflections off tiny ice platelets floating in the air nearly horizontally. Such deep space detection of tropospheric ice can be used to constrain the likelihood of oriented …

Topological Tight-Binding Models From Nontrivial Square Roots, J. Arkinstall, M. H. Teimourpour, L. Feng, Ramy El-Ganainy, H. Schomerus

Department of Physics Publications

We describe a versatile mechanism that provides tight-binding models with an enriched, topologically nontrivial band structure. The mechanism is algebraic in nature, and leads to tight-binding models that can be interpreted as a nontrivial square root of a parent lattice Hamiltonian—in analogy to the passage from a Klein-Gordon equation to a Dirac equation. In the tight-binding setting, the square-root operation admits to induce spectral symmetries at the expense of broken crystal symmetries. As we illustrate in detail for a simple one-dimensional example, the emergent and inherited spectral symmetries equip the energy gaps with independent topological quantum numbers that control the …

Non-Hermitian Engineering Of Synthetic Saturable Absorbers For Applications In Photonics, M. H. Teimourpour, A. Rahman, K. Srinivasan, Ramy El-Ganainy

Department of Physics Publications

We explore a type of synthetic saturable absorber based on quantum-inspired photonic arrays. We demonstrate that the interplay between optical Kerr nonlinearity, interference effects, and non-Hermiticity through radiation loss leads to a nonlinear optical filtering response with two distinct regimes of small and large optical transmissions. More interestingly, we show that the boundary between these two regimes can be very sharp. The threshold optical intensity that marks this abrupt “phase transition” and its steepness can be engineered by varying the number of the guiding elements. The practical feasibility of these structures as well as their potential applications in laser systems …

The Intrinsic Variability Of The Water Vapor Saturation Ratio Due To Mixing, Jesse Anderson

Dissertations, Master's Theses and Master's Reports

The water vapor concentration plays an important role for many atmospheric processes. The mean concentration is key to understand water vapor's effect on the climate as a greenhouse gas. The fluctuations about the mean are important to understand heat fluxes between Earth's surface and the boundary layer. These fluctuations are linked to turbulence that is present in the boundary layer. Turbulent conditions are simulated in Michigan Tech’s multiphase, turbulent reaction chamber, the π chamber. Measurements for temperature and water vapor concentration were recorded under forced Rayleigh- Bénard convection at several turbulent intensities. These were used to calculate the saturation ratio, …

Quantum Inspired Symmetries In Laser Engineering, Mohammad Hosain Teimourpour

Dissertations, Master's Theses and Master's Reports

In this thesis, quantum inspired symmetries including Parity-Time (PT) symmetry and Supersymmetry (SUSY) have been studied in the context of non-Hermitian engineered laser systems. This thesis starts with a short review of semiconductor lasers theory in second chapter, followed by an introduction to quantum inspired symmetries: PT symmetry and SUSY in optics and photonics in chapter three.

In chapter four, we have studied the robustness and mode selectivity in PT symmetric lasers. We investigate two important aspects of PT symmetric photonic molecule lasers, namely the robustness of their single longitudinal mode operation against instabilities triggered by spectral hole burning effects, …

Gamma/Hadron Separation For The Hawc Observatory, Michael J. Gerhardt

Dissertations, Master's Theses and Master's Reports

The High-Altitude Water Cherenkov (HAWC) Observatory is a gamma-ray observatory sensitive to gamma rays from 100 GeV to 100 TeV with an instantaneous field of view of ~2 sr. It is located on the Sierra Negra plateau in Mexico at an elevation of 4,100 m and began full operation in March 2015. The purpose of the detector is to study relativistic particles that are produced by interstellar and intergalactic objects such as: pulsars, supernova remnants, molecular clouds, black holes and more. To achieve optimal angular resolution, energy reconstruction and cosmic ray background suppression for the extensive air showers detected by …