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Physics Graduate Theses & Dissertations

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Mechanisms For Fracton Phases, Han Ma Jan 2019

Mechanisms For Fracton Phases, Han Ma

Physics Graduate Theses & Dissertations

Strongly correlated many-body systems provide a platform for novel phases of matter where constituent particles organize themselves in a variety of ways. At low temperature, these particles interact quantum mechanically and generate entanglement building up exotic quantum phases, such as topologcial order, where there can be emergent excitations which cannot be created locally. Such excitations, if gapped, are also called topological excitations.

Fracton is one of such gapped point-like topological excitation in three dimensional system. Different from conventional topological excitation, it is immobile and was firstly discovered in exact solvable models exhibiting fracton topological order. This new order has sub-extensive ...


Precise Measurements Of Few-Body Physics In Ultracold 39k Bose Gas, Roman Chapurin Jan 2019

Precise Measurements Of Few-Body Physics In Ultracold 39k Bose Gas, Roman Chapurin

Physics Graduate Theses & Dissertations

Ultracold atomic gases with tunable interactions offer an ideal platform for studying interacting quantum matter. While the few- and many-body physics are generally complex and intractable, the problem can be greatly simplified in an atomic gas by a controlled separation of relevant length and energy scales. Precise control of experimental parameters, via Feshbach resonances, optical potentials and radio-frequency radiation, enables deterministic measurements of few-body physics, including universal physics and the Efimov effect. In this thesis, I present our recent studies on precisely measuring two- and three-body physics in an ultracold Bose gas. I begin by describing our new apparatus used ...


Understanding And Manipulating The Thermal Conductance Of Sin Membranes In Sub-Kelvin Refrigerators And Sensors, Xiaohang Zhang Jan 2019

Understanding And Manipulating The Thermal Conductance Of Sin Membranes In Sub-Kelvin Refrigerators And Sensors, Xiaohang Zhang

Physics Graduate Theses & Dissertations

In superconducting transition-edge sensors (TES) and superconducting tunnel junction refrigerators, thermal conductance of the silicon nitride membrane is a key design character. Thermal conductance engineering in silicon nitride membrane is still challenging, especially not introducing extra noise to sensors and diminish its mechanical strength.

In this thesis, we introduce our new generation of macroscopic general-purpose refrigerator using superconducting tunnel junction. Using the product of the cooled mass and the temperature reduction as a performance metric, this work is a more than tenfold advance over previous efforts. Based on our model, a better understanding of phonon thermal conductance of silicon nitride ...


Achieving A Large Density Of Hydroxyl Radicals For Cold Collisions, Hao Wu Jan 2019

Achieving A Large Density Of Hydroxyl Radicals For Cold Collisions, Hao Wu

Physics Graduate Theses & Dissertations

Molecular physics has experienced groundbreaking progress in the fields of precision spectroscopy, chemical reaction kinetics, quantum state engineering and many-body physics. In order to better observe these phenomena, there is an insatiable pursuit of larger trapped molecular densities and longer lifetime. In this thesis, several key milestones that we have recently achieved towards these goals for hydroxyl radicals (OH) are reported. First, we discovered an enhanced spin-flip behavior of dipolar molecules due to the existence of dual (electric and magnetic) dipole moments and obtained a better understanding of complex spin-dynamics for both Hund's case (a) and (b) molecules in ...


Investigating And Valuing The Messy Nature Of Learning: Ontological, Epistemological, And Social Aspects Of Student Reasoning In Quantum Mechanics, Jessica Rae Hoehn Jan 2019

Investigating And Valuing The Messy Nature Of Learning: Ontological, Epistemological, And Social Aspects Of Student Reasoning In Quantum Mechanics, Jessica Rae Hoehn

Physics Graduate Theses & Dissertations

Historically, much of physics education research has focused on whether students’ answers are correct or incorrect. This thesis presents a complementary perspective that moves beyond a dichotomous view of learning by valuing the messy, or complicated and varied, nature of students’ reasoning. We do so by investigating three aspects of student reasoning in quantum mechanics (QM)---ontological (pertaining to the nature of entities), epistemological (pertaining to the nature of knowledge or learning), and social (pertaining to collective reasoning). Through focusing on the kinds of reasoning that students are capable of, we value their creativity, identity, and engagement in our educational ...


The Road Less Traveled: Resonant Bose-Einstein Condensates Via A Hyperspherical Lowest-Order Constrained Variational Approach, Michelle Wynne Ching Sze Jan 2019

The Road Less Traveled: Resonant Bose-Einstein Condensates Via A Hyperspherical Lowest-Order Constrained Variational Approach, Michelle Wynne Ching Sze

Physics Graduate Theses & Dissertations

In this work, we study the ground state properties of a system of $N$ harmonically trapped bosons of mass $m$ interacting with two-body contact interactions, from small to large scattering lengths. This is accomplished in a hyperspherical coordinate system that is flexible enough to describe both the overall scale of the gas and two-body correlations. By adapting the lowest-order constrained variational (LOCV) method, we are able to semi-quantitatively attain Bose-Einstein condensate ground state energies even for gases with infinite scattering length. In the large particle number limit, our method provides analytical estimates for the energy per particle $E_0/N \approx ...


Resonantly Interacting Degenerate Bose Gas Oddities, Catherine Ellen Klauss Aug 2018

Resonantly Interacting Degenerate Bose Gas Oddities, Catherine Ellen Klauss

Physics Graduate Theses & Dissertations

The progression from two- through few- to many-body physics is an open and interesting question. Experiments that can test these theories must walk the fine line between cultivating a rich many-body system, yet preventing the interactions from completely destroying the system before study. This thesis explores the two- and few-body interactions present in a resonantly interacting degenerate Bose gas. We explore these interactions as a function of the density of the initial Bose-Einstein condensate. We use loss rates to characterize the interactions and find that a significant portion of the perceived atomic loss is from sweeping the atoms into loosely ...


Attosecond Light Pulses And Attosecond Electron Dynamics Probed Using Angle-Resolved Photoelectron Spectroscopy, Cong Chen Aug 2018

Attosecond Light Pulses And Attosecond Electron Dynamics Probed Using Angle-Resolved Photoelectron Spectroscopy, Cong Chen

Physics Graduate Theses & Dissertations

Recent advances in the generation and control of attosecond light pulses have opened up new opportunities for the real-time observation of sub-femtosecond (1 fs = 10-15 s) electron dynamics in gases and solids. Combining attosecond light pulses with angle-resolved photoelectron spectroscopy (atto-ARPES) provides a powerful new technique to study the influence of material band structure on attosecond electron dynamics in materials. Electron dynamics that are only now accessible include the lifetime of far-above-bandgap excited electronic states, as well as fundamental electron interactions such as scattering and screening. In addition, the same atto-ARPES technique can also be used to measure the ...


Overcoming Limitations In Semiconductor Alloy Design, Theresa M. Christian Feb 2018

Overcoming Limitations In Semiconductor Alloy Design, Theresa M. Christian

Physics Graduate Theses & Dissertations

Inorganic semiconductors provide an astonishingly versatile, robust, and efficient platform for optoelectronic energy conversion devices. However, conventional alloys and growth regimes face materials challenges that restrict the full potential of these devices. Novel alloy designs based on isoelectronic co-doping, metamorphic growth and controllable atomic ordering offer new pathways to practical and ultra-high-efficiency optoelectronic devices including solar cells and light-emitting diodes.

Abnormal isoelectronic alloys of GaP1-xBix, GaP1-x-yBixNy, and GaAs1-xBix with unprecedented bismuth incorporation fractions and crystalline quality are explored in this thesis research. Comparative studies of several GaP1-xBi ...


Ge-Sb-Se Chalcogenide Glass For Near- And Mid-Infrared Nonlinear Photonics, Molly Rebecca Krogstad Feb 2018

Ge-Sb-Se Chalcogenide Glass For Near- And Mid-Infrared Nonlinear Photonics, Molly Rebecca Krogstad

Physics Graduate Theses & Dissertations

The chalcogenide glass, Ge28Sb12Se60, is a promising material platform for compact, low-threshold nonlinear optical devices operating in the near- to mid-infrared. It is particularly attractive given its wide range of transparency, large Kerr coefficient, and relatively weak multi-photon absorption. The nonlinear optical properties of Ge28Sb12Se60 were investigated in bulk and waveguide forms, over a range of wavelengths from 1.0 to 3.5 μm. From z-scan measurements at 1.03 µm, using circularly polarized, 200 fs pulses at 374 kHz, bulk Ge28Sb12Se60 glass was found ...


Widely Tunable On-Chip Microwave Circulator For Superconducting Quantum Circuits, Ben J. Chapman Jan 2018

Widely Tunable On-Chip Microwave Circulator For Superconducting Quantum Circuits, Ben J. Chapman

Physics Graduate Theses & Dissertations

This thesis develops theory for and experimentally demonstrates a new way to break Lorentz reciprocity—the symmetry, in an electrical network, under exchange of source and detector. The approach is based on the sequential application of frequency conversion and delay; as frequency and time are Fourier duals, these operations do not generally commute. We apply this method in the construction of an on-chip superconducting microwave circulator, a critical component for the unidirectional routing of quantum information in superconducting networks. The device requires neither permanent magnets nor microwave control tones, allowing on-chip integration with other superconducting circuits without expensive control hardware ...


A Three-Dimensional Mot Of Yo Towards Narrow-Line Cooling, Alejandra Louise Collopy Jan 2018

A Three-Dimensional Mot Of Yo Towards Narrow-Line Cooling, Alejandra Louise Collopy

Physics Graduate Theses & Dissertations

Laser cooling and magneto-optical trapping of neutral atoms has been a driving force in physics over the last few decades by providing an efficient method to produce cold and dense samples of cold atoms. Polar molecules which can have strong, long-range dipolar interactions and possess more rich internal structure promise a wide range of new physics and chemistry studies if they can be controlled efficiently. Until recently, the only way to achieve sub-milliKelvin level temperatures in molecules was to associate two precooled atomic species, which while very effective, has a firm bound on the chemical diversity accessible. While laser cooling ...


Computational Modeling Of Mitosis In Fission Yeast, Christopher Edelmaier Jan 2018

Computational Modeling Of Mitosis In Fission Yeast, Christopher Edelmaier

Physics Graduate Theses & Dissertations

Mitosis ensures the proper segregation of chromosomes into daughter cells, which is accomplished by the mitotic spindle. During fission yeast mitosis, chromosomes establish bi-orientation as the bipolar spindle assembles, meaning that sister kinetochores become attached to microtubules whose growth was initiated by the two sister poles. This process includes mechanisms that correct erroneous attachments made by the kinetochores during the attachment process. This thesis presents a 3D physical model of spindle assembly in a Brownian dynamics-kinetic Monte Carlo simulation framework and a realistic description of the physics of microtubule, kinetochore, and chromosome dynamics, in order to interrogate the dynamics and ...


Beyond Modelocking: High Repetition-Rate Frequency Combs Derived From A Continuous-Wave Laser, Daniel C. Cole Jan 2018

Beyond Modelocking: High Repetition-Rate Frequency Combs Derived From A Continuous-Wave Laser, Daniel C. Cole

Physics Graduate Theses & Dissertations

Optical frequency combs based on modelocked lasers have revolutionized precision metrology by facilitating measurements of optical frequencies, with implications both for fundamental scientific questions and for applications such as fast, broadband spectroscopy. In this thesis, I describe advances in the generation of frequency combs without modelocking in platforms with smaller footprints and higher repetition rates, with the ultimate goal of bringing frequency combs to new applications in a chip-integrated package. I discuss two approaches for comb generation: parametric frequency conversion in Kerr microresonators and active electro-optic modulation of a continuous-wave laser. After introducing microresonator-based frequency combs (microcombs), I discuss two ...


Dynamics Of Crowded And Active Biological Systems, Michael W. Stefferson Jan 2018

Dynamics Of Crowded And Active Biological Systems, Michael W. Stefferson

Physics Graduate Theses & Dissertations

Interactions between particles and their environment can alter the dynamics of biological systems. In crowded media like the cell, interactions with obstacles can introduce anomalous subdiffusion. Active matter systems, e.g., bacterial swarms, are nonequilibrium fluids where interparticle interactions and activity cause collective motion and dynamical phases. In this thesis, I discuss my advances in the fields of crowded media and active matter. For crowded media, I studied the effects of soft obstacles and bound mobility on tracer diffusion using a lattice Monte Carlo model. I characterized how bound motion can minimize the effects of hindered anomalous diffusion and obstacle ...


Many-Body Physics In An Optical Lattice Clock, Sarah Louise Bromley Jan 2018

Many-Body Physics In An Optical Lattice Clock, Sarah Louise Bromley

Physics Graduate Theses & Dissertations

In this work we study the effect of interactions in an optical lattice clock based on fermionic Sr atoms. In current one-dimensional lattice clocks nuclear spin-polarized atoms are known to have contact interactions of p-wave character and collective in nature. Here we focus on interactions that will influence the design of future optical lattice clocks. We study the case where atoms are no longer confined to a single nuclear spin state. By using samples of atoms with different distributions among the ten nuclear spin states of Sr we show that these interactions are SU(N) symmetric up to a ...


Aspects Of Topology In Quantum Phases Of Matter: A Journey Through Lands Both Flat And Not, Abhinav Prem Jan 2018

Aspects Of Topology In Quantum Phases Of Matter: A Journey Through Lands Both Flat And Not, Abhinav Prem

Physics Graduate Theses & Dissertations

Topological quantum phases of matter are often characterized by the presence of fractionalized quasiparticles, which exhibit non-trivial braiding statistics or carry fractional quantum numbers, or of protected gapless surface states. In this thesis, we study topological phases in two and three spatial dimensions, from the perspective of searching for new exotic quantum phases and of characterizing their experimental signatures.

We first study topological defects in fermionic paired superfluids and discover that in the presence of a multiply quantized vortex, such a state hosts unpaired fermions in the BCS regime. We predict that these unpaired fermions will result in an experimentally ...


The First Precision Measurement Of The Electron Electric Dipole Moment In Trapped Molecular Ions, Daniel Gresh Jan 2018

The First Precision Measurement Of The Electron Electric Dipole Moment In Trapped Molecular Ions, Daniel Gresh

Physics Graduate Theses & Dissertations

A measurement of the permanent electric dipole moment of the electron (eEDM, de) is a direct probe of physics beyond the Standard Model. Our experiment makes a measurement of the eEDM in Hafnium Fluoride ions (HfF) using a novel radiofrequency ion trap where we routinely achieve measurement coherence times of > 1 s. This thesis presents the result of our first generation eEDM measurement, where we measure de = (0.9±7.7stat±1.7syst) ✕ 10-29e⋅cm, a value consistent with zero, which corresponds to a 90\% confidence upper bound of de < 1.3 ✕ 10-28 e ⋅ cm ...


Liquid Crystals Formed By Short Dna Oligomers And The Origin Of Life, Gregory Patrick Smith Jan 2018

Liquid Crystals Formed By Short Dna Oligomers And The Origin Of Life, Gregory Patrick Smith

Physics Graduate Theses & Dissertations

When dissolved in water, base paired DNA oligomers form double helices with sufficient structural rigidity that, if they are at high enough concentration, can undergo a phase transition into chiral nematic or hexagonal columnar liquid crystalline (LC) order. Within these LC phases, constrained orientation allows these rods to stack more efficiently by hydrophobic forces than they would otherwise, building them into long double helical aggregates that can be chemically glued together (ligated) to further increase their lengths. Even in absence of chemical ligation, this stacking effect is strong enough that short DNA oligomers, which are otherwise too short to form ...


Strongly Interacting Fermi Gases: Hydrodynamics And Beyond, William E. Lewis Jan 2018

Strongly Interacting Fermi Gases: Hydrodynamics And Beyond, William E. Lewis

Physics Graduate Theses & Dissertations

This thesis considers out-of-equilibrium dynamics of strongly interacting non-relativistic Fermi gases in several two and three dimensional geometries. The tools of second-order hydrodynamics and gauge-gravity duality will be utilized to address this system. Many of the themes of this work are motivated by the observed similarities in transport properties between strongly interacting Fermi gases and other very different strongly interacting quantum fluids such as the quark-gluon plasma, high temperature superconductors, and quantum field theories described by gauge-gravity duality. In particular, these systems all nearly saturate the conjectured lower bound on the ratio of shear viscosity to entropy density η/s ...


Search For A Heavy Resonance Decaying To A Pair Of Higgs Bosons In The Four B-Quark Final State With The Cms Experiment, Michael D. Krohn Jan 2018

Search For A Heavy Resonance Decaying To A Pair Of Higgs Bosons In The Four B-Quark Final State With The Cms Experiment, Michael D. Krohn

Physics Graduate Theses & Dissertations

A search for a massive resonance decaying into a pair of standard model Higgs bosons, in a final state consisting of two b quark-antiquark pairs, is performed using proton-proton collisions at a center-of-mass energy of 13 TeV collected by the Compact Muon Solenoid detector at the Large Hadron Collider and corresponding to an integrated luminosity of 35.9 fb-1. The Higgs bosons are highly Lorentz-boosted and are each reconstructed as a single large-area jet. The signal is characterized by a peak in the dijet invariant mass distribution, above a background from the standard model multijet production. The observations are ...


Polarization Dependent Angle Resolved Photoemission Spectroscopy For The Determination Of Intrinsic Material Symmetries, Thomas J. Nummy Jan 2018

Polarization Dependent Angle Resolved Photoemission Spectroscopy For The Determination Of Intrinsic Material Symmetries, Thomas J. Nummy

Physics Graduate Theses & Dissertations

In this thesis I investigate the utility of the polarization and angle dependence of the photoemission matrix element in angle resolved photoemission spectroscopy (ARPES). This technique is capable of determining internal symmetries of the electronic wave functions in crystalline solids and has been historically underutilized in the ARPES community. In Chapter 1, I introduce the ARPES technique, the established theory and models behind it, and the experimental considerations in performing the technique. It is my personal belief that the fastest way to build intuition for complex physical phenomena is through simulation, and a good portion of graduate school career was ...


Shaken Lattice Interferometry, Carrie Ann Weidner Jan 2018

Shaken Lattice Interferometry, Carrie Ann Weidner

Physics Graduate Theses & Dissertations

Since the first demonstrations in 1991, atom interferometry has been a burgeoning field of research. The work done in this field is motivated by the potential sensitivity improvements that atom-based devices can have over the current state-of-the-art light- and MEMS-based devices. This dissertation presents a new and unique approach to atom interferometry in that we perform the basic interferometric sequence of splitting, propagation, reflection, reverse-propagation, and recombination with atoms trapped in a phase-modulated (shaken) optical lattice. In both simulation and experiment we demonstrate a one-dimensional shaken lattice interferometer configured as an accelerometer. The interferometry sequence is developed through the use ...


Beyond The Standard Model With Composite Particles: A Lattice Study Based On Su(4), William I. Jay Jan 2018

Beyond The Standard Model With Composite Particles: A Lattice Study Based On Su(4), William I. Jay

Physics Graduate Theses & Dissertations

This thesis is about numerical simulations of a strongly coupled quantum field theory. The quantum field theory is a gauge theory based on the group SU(4) and contains fermionic matter charged under two different representations of the gauge group. The motivation for studying this theory is twofold. First, this theory is closely related to a theory of physics beyond the Standard Model which was recently proposed in the literature. In this model, the Higgs boson is a composite particle, and the top quark is a partially composite particle. Second, theories of this sort represent a new direction in the ...


Search For Supersymmetry Using Boosted Higgs Bosons And Missing Transverse Momentum In Proton-Proton Collisions At 13 Tev, Frank Owen Jensen Jan 2018

Search For Supersymmetry Using Boosted Higgs Bosons And Missing Transverse Momentum In Proton-Proton Collisions At 13 Tev, Frank Owen Jensen

Physics Graduate Theses & Dissertations

A search for physics beyond the Standard Model in events with one or more high-momentum Higgs bosons decaying to pairs of b quarks in association with missing transverse momentum is presented. The data, corresponding to an integrated luminosity of 35.9 fb-1, were collected with the CMS detector at the Large Hadron Collider in proton-proton collisions at the center-of-mass energy √s = 13TeV. The analysis utilizes a new b quark tagging technique based on jet substructure to identify jets from Higgs ⟶ decays. Events are categorized by the number of -tagged jets, the mass of the jets, and the ...


Ultrafast Dynamics Of Magnetic Multilayer Films: Magneto-Optical Spectroscopy And Resonant Scattering In The Extreme Ultraviolet And Soft X-Ray Spectral Regions, Dmitriy Zusin Jan 2018

Ultrafast Dynamics Of Magnetic Multilayer Films: Magneto-Optical Spectroscopy And Resonant Scattering In The Extreme Ultraviolet And Soft X-Ray Spectral Regions, Dmitriy Zusin

Physics Graduate Theses & Dissertations

This thesis focuses on studying ferromagnetic thin films with high temporal and spatial resolution using tabletop extreme ultraviolet (EUV) light sources based on high harmonic generation (HHG) and ultrafast soft X-rays from a free-electron laser. In Chapter 4, a new magneto-optical technique is developed. It allows a direct measurement of the full resonant complex EUV magneto-optical permittivity on a tabletop and thus, through a comparison with first principles calculations, is capable of capturing the microscopic mechanisms of ultrafast laser-induced demagnetization. It is found that, in Co, the demagnetization response is dominated by magnon excitations with possible smaller contributions from other ...


On Kinetic Transport In Small System Collectivity And A Measurement Of Separated Open Heavy Flavor Production In P+P Collisions At $\Sqrt{S}=200$ Gev, Javier Orjuela Koop Jan 2018

On Kinetic Transport In Small System Collectivity And A Measurement Of Separated Open Heavy Flavor Production In P+P Collisions At $\Sqrt{S}=200$ Gev, Javier Orjuela Koop

Physics Graduate Theses & Dissertations

The present dissertation consists of two distinct parts. The first one is a comprehensive study of collective behavior in small collision systems from the point of view of kinetic theory, in which the medium formed in heavy-ion collisions is modeled as a collection of interacting quasiparticles. We investigate how parton scattering, where individual partons undergo very few scatters, can translate the initial collision geometry to final-state azimuthal anisotropy, yielding results in agreement with experimental data in a variety of systems, from 3He+Au to p+p collisions, and over a wide range of collision energies, prompting the question of ...


Single Atom Delivery Into A Bottle Beam Trap Using An Optical Conveyor Belt And Quantum Coherent Gain In A Matterwave Transistor, Brad Anthony Dinardo Jan 2018

Single Atom Delivery Into A Bottle Beam Trap Using An Optical Conveyor Belt And Quantum Coherent Gain In A Matterwave Transistor, Brad Anthony Dinardo

Physics Graduate Theses & Dissertations

The work of this dissertation falls into two broad categories. In the first part, I describe loading a single atom from a reservoir into a blue-detuned crossed vortex bottle beam trap using a dynamic 1D optical lattice. The lattice beams are frequency chirped using acousto-optic modulators, which causes the lattice to move along its axial direction and behave like an optical conveyor belt. A stationary lattice is initially loaded with approximately 6000 atoms from a reservoir, and the conveyor belt transports them 1.1 mm from the reservoir to a bottle beam trap, where a single atom is loaded via ...


Revealing The Nanoscale Structure And Properties Of The Twist-Bend Nematic Liquid Crystal Phase, Michael Ryan Tuchband Jan 2018

Revealing The Nanoscale Structure And Properties Of The Twist-Bend Nematic Liquid Crystal Phase, Michael Ryan Tuchband

Physics Graduate Theses & Dissertations

The nematic phases of liquid crystals have been the most thoroughly investigated since the founding of the liquid crystal field in the early 1900’s. The resulting technologies, most notably the liquid crystal display, have changed our world and spawned an entire industry. Consequently, the recent identification of a new type of nematic – the twist-bend nematic – was met with as much surprise as excitement, as it melds the fluid properties and environmental responsiveness of conventional nematics with the intrinsic polarization and complex ordering of bent-core liquid crystals. I summarize the history of the twist-bend nematic phase, charting the development of ...


Cavity Qed With Exciton Polaritons Using Two-Dimensional Coherent Spectroscopy, Travis Marshall Autry Nov 2017

Cavity Qed With Exciton Polaritons Using Two-Dimensional Coherent Spectroscopy, Travis Marshall Autry

Physics Graduate Theses & Dissertations

In semiconductors the band edge absorption properties are dominated by Coulomb bound electron-hole pairs known as excitons. In an isotropic ideal infinite crystal such as a bulk semiconductors the exciton does not decay to a ground state but instead exchanges energy with the internal modes of the electromagnetic field found from the same boundary conditions as the crystal. It is only the leakage of photons out of the crystal due to real crystals having finite size that allows the exciton-light field to decay. This exchange of energy led to the concept of the exciton-polariton which represents the coupled system of ...