Physical Sciences and Mathematics Commons^™

Analog Cosmology And Superfluidity In Atomic Gases And Electronic Materials, Anshuman Bhardwaj

LSU Doctoral Dissertations

We present a study of analog cosmological models in Bose-Einstein condensates (BEC) and in graphene, and superfluidity in a box-shaped traps. We start by examining the dynamics of a Bose-Einstein condensate (BEC) trapped inside an expanding toroid that can realize an analog inflationary universe. The expanding condensate forces phonons to undergo redshift and damping due to quantum pressure, owing to the thinness of the ring. We predict that such expanding BECs can exhibit spontaneous phonon creation from the vacuum state and show how it would manifest in the atom density and density correlations and discuss connections with the inflationary theory. …

Theoretical Investigation On Optical Properties Of 2d Materials And Mechanical Properties Of Polymer Composites At Molecular Level, Geeta Sachdeva

Dissertations, Master's Theses and Master's Reports

The field of two-dimensional (2D) layered materials provides a new platform for studying diverse physical phenomena that are scientifically interesting and relevant for technological applications. Theoretical predictions from atomically resolved computational simulations of 2D materials play a pivotal role in designing and advancing these developments. The focus of this thesis is 2D materials especially graphene and BN studied using density functional theory (DFT) and molecular dynamics (MD) simulations. In the first half of the thesis, the electronic structure and optical properties are discussed for graphene, antimonene, and borophene. It is found that the absorbance in (atomically flat) multilayer antimonene (group …

Toward Devices For Exploring Pt-Symmetry In Electronic Transport Of Graphene, Michael Carovillano

Senior Honors Papers / Undergraduate Theses

Parity-time symmetry, or PT -symmetry is the principle that in quantum mechanics a non- Hermitian Hamiltonian is capable of returning real eigenstates and real spectra.Recent research has demonstrated real world observation of PT -symmetry in electronics and optics. We aim to expand the regime of observed PT -symmetry through measurement of the electronic transport of graphene devices. Drawing from analogous experiments, we plan to use balanced ohmic resistance acting as both loss and relative gain to induce the required unbroken PT -symmetry regime. This paper analyzes techniques used in fabrication of such devices as well as the basis of the …

Electron Transport In One And Two Dimensional Materials, Samuel William Lagasse

Legacy Theses & Dissertations (2009 - 2024)

This dissertation presents theoretical and experimental studies in carbon nanotubes (CNTs), graphene, and van der Waals heterostructures. The first half of the dissertation focuses on cutting edge tight-binding-based quantum transport models which are used to study proton irradiation-induced single-event effects in carbon nanotubes [1], total ionizing dose effects in graphene [2], quantum hall effect in graded graphene p-n junctions [3], and ballistic electron focusing in graphene p-n junctions [4]. In each study, tight-binding models are developed, with heavy emphasis on tying to experimental data. Once benchmarked against experiment, properties of each system which are difficult to access in the laboratory, …

The Study Of Nano-Optics In Hybrid Systems, Marek J. Brzozowski

Electronic Thesis and Dissertation Repository

In this thesis, we study the quantum light-matter interaction in polaritonic heterostructures. These systems are made by combining various nanocomponents, such as quantum dots, graphene films, metallic nanoparticles and metamaterials. These heterostructures are used to develop new optoelectronic devices due to the interaction between nanocomposites.

Photoluminescence quenching and absorption spectrum are determined and an explanatory theory is developed for these polaritonic heterostructures. Photoluminescence quenching is evaluated for a graphene, metallic nanoparticle and quantum dot system. It is shown that average distance between nanocomposites or concentration of nanocomposites affect the output these system produced. Photoluminescence quenching was also evaluated for a …

Mirror Buckling Transitions In Freestanding Graphene Membranes Induced Through Scanning Tunneling Microscopy, James Kevin Schoelz

Graduate Theses and Dissertations

Graphene has the ability to provide for a technological revolution. First isolated and characterized in 2004, this material shows promise in the field of flexible electronics. The electronic properties of graphene can be tuned by controlling the shape of the membrane. Of particular interest in this endeavor are the thermal ripples in graphene membranes. Years of theoretical work by such luminaries as Lev Landau, Rudolf Peierls, David Mermin and Herbert Wagner have established that 2D crystals should not be thermodynamically stable. Experimental research on thin films has supported this finding. Yet graphene exists, and freestanding graphene films have been grown …

Transport And Optical Properties Of Quantized Low-Dimensional Systems, Xiaoguang Li

Doctoral Dissertations

In this thesis, we present a systematic investigation of the static and dynamic response properties of low-dimensional systems, using a variety of theoretical techniques ranging from time dependent density functional theory to the recursive Green's function method.

As typical low-dimensional systems, metal nanostructures can strongly interact with an electric field to support surface plasmons, making their optical properties extremely attractive in both fundamental and applied aspects. We have investigated the energy broadening of surface plasmons in metal structures of reduced dimensionality, where Landau damping is the dominant dissipation channel and presents an intrinsic limitation to plasmonics technology. We show that …