Chip-based photonic devices are doing for optics what integrated circuits have done for electronics. By directly combining many individual components in a compact, scalable and robust way, photonic chips open the possibility for creating optical and electro-optical devices that could not be practical with discrete components. The applications for this...
At the interface of two dissimilar entities, something novel can emerge. This idea has driven a vast amount of fruitful work on semiconductor interfaces, and given us the digital revolution. In the past decade, remarkable progress has been made in the synthesis and understanding of interfaces between oxides, opening up...
X-ray reflectivity (XRR) versatile technique that characterize the surface structures. However, due to the lack of phase information of X-ray data, the reconstruction of electron density profile (EDP) from XRR data is an ill-posed inverse problem that requires extra attention. In Chapter 1, several key concepts in XRR data analysis...
In this thesis I present the theoretical work on Fermionic surface states, and bulk Bosonic collective excitations in topological superfluids and superconductors. Broken symmetries in topological condensed matter systems have implications for the spectrum of Fermionic excitations confined on surfaces or topological defects.
For the B-phase of superfluid 3He, which...
Science at the nanoscale poses several recurring difficulties. How can we control the assembly of objects too small for direct manipulation to be practical? How can we extend that control to extit{in vivo} systems so we can make use of nanotechnology in medicine? And how can we recreate the extraordinary...
Lattice models of fermions, bosons, and spins have long served to elucidate the essential physics of quantum phase transitions in a variety of systems. Generalizing such models to incorporate driving and dissipation has opened new vistas to investigate nonequilibrium phenomena and dissipative phase transitions in interacting many-body systems. Circuit- QED...
This dissertation presents some development of the single molecular ion precision spectroscopy experiment including construction of the project, spectroscopy state readout, and production of ultracold molecules. Such molecular ion spectroscopy aims at testing fundamental physics such as probing the time variation of electron-proton mass ratio.
The theories and characterization of...
A fundamental materials science question is “why and how will this material form?” The experimental,computation, and time resources necessary to answer this question consume significant resources due to the
predominantly trial-and-error based approaches common in materials research. This dissertation reintroduces
a number of fundamental thermodynamics-based tools for the study of...
Coherent diffractive imaging (CDI) methods are techniques that image a sample by illuminating it with a coherent beam and recording the intensity diffraction pattern produced by the wavefront outgoing from the sample. These are lensless methods that are not limited in resolution by the physical characteristics of an objective lens,...
Renewable energy technology, more so than ever before, is critical to the survival of humanity. For decades, concentrated efforts into designing and developing such novel devices resulted in the innovation of solar-driven photovoltaics that were competitive with nonrenewable alternatives. This thesis explores the dynamic behavior of alternative material candidates that...
Engineering responses of soft materials at hierarchical time and length scales is of great interest to both fundamental science and technological applications. In recent years, the hybridization between emerging soft condense matters and conventional hard condense matters keeps enriching the materials library of humankind and opens another largely-uncharted venue for...
Light is a powerful tool for manipulating and probing magnetic states in solid state systems. In particular, optically-induced spin orientation, the ability to orient spin with polarized light, has been extensively utilized in low-dimensional III-V and II-VI semiconductors to pioneer spintronic research. Even though traditional semiconductors have found a wide...
On-shell formulations of scattering amplitudes for quantum field theories, without utilizating the local descriptions of Lagrangian and Feynman diagrams, have become increasingly useful and important in recent years for both formal and practical reasons. The nonlinear sigma model (NLSM), which describes the interactions between Nambu-Goldstone bosons, is an ideal testing...
Superconducting qubits are among the leading competitors in the race towards building the first full-fledged quantum computer. Using this platform, researchers have for the first time demonstrated computational capability that is beyond the reach of the current classical machines. (This achievement is nicknamed "Quantum Supremacy".) Up to date, however, the...
Quantum technologies have the capability of greatly increasing the security of communication systems. Many components are required for a full quantum network including memory, repeaters, routers, and detectors. The efficiencies of quantum communication technologies suffer greatly due to their inherent sensitivity to loss. Low-loss propagation and high detection efficiency can...
The nature of dark matter (DM) remains one of the largest open questions in modern physics despite the many searches for particle dark matter around the world. The search for dark matter particles with masses above 5 GeV/$c^2$ is led by the dual-phase xenon time-projection chamber (LXe-TPC) detector technology which...
The BV Laplacian Δ, first introduced by Batalin and Vilkovisky, is a second-order differential operator that appears in the quantum master equation for quantizing gauge theories. The geometric framework for the BV formalism was later recognized by Schwarz as the setting of odd symplectic geometry and Khudaverdian showed that Δ...
The effect of interfaces in solids on the overall charge transport properties has become a topic of growing importance for energy materials such as thermoelectrics. In some polycrystalline thermoelectric materials, the performance near room temperature is significantly limited due to thermally-activated electrical conductivity near room-temperature, which can be attributed to...
Given directives such as the UN Global Goals targeting sustainable development, the research presented herein makes but a small contribution to the advancement of alternative energy technologies. Nevertheless, the present work was largely motivated to address specific points of intrigue within the thermoelectrics community. The general principles demonstrated, however, may...
Interfacial science brings together diverse areas of interest such as electronic materials, quantum materials, bio-membranes and catalysts. In-situ X-ray characterization techniques can be used to understand the assembly of atoms, molecules and supported nanoparticles at interfaces in complex environments. This thesis work focuses on the use of various X-ray characterization...
Micro-X is a high-resolution X-ray spectroscopy sounding rocket mission that had its first flight in July 2018, becoming the first program to carry Transition-Edge Sensors (TES) and multiplexing Superconducting QUantum Interference Device (SQUID) readout electronics into space, successfully collect data, and subsequently recover the instruments. While a rocket pointing failure...
The presented thesis introduces our work of extending high-resolution x-ray 3D imaging towards extended samples. With the advent of x-ray sources with higher brightness and better coherence, as well as the rise of the needs to examine the fine structures of large objects in the field of materials science, biology,...
The leptonic and inclusive hadronic decay branching fractions of the W boson are studied using 35.9 $fb^{-1}$ of proton-proton collision data collected at $\sqrt{s}=13~TeV$ during the 2016 run of the CMS experiment. Events characterized by the production of pairs of W bosons from \ttbar and \tW processes are selected. Multiple...
As polymer science has advanced as a field, so too have the uses for polymeric materials. We encounter polymers and plastics on a daily basis, and while their presence has greatly improved our quality of life, they have also had a profound and often negative impact on our environment. Plastic...
Electrostatic interactions mediated by ionic environments play a central role in physical processes across materials science, chemistry and biology. Key biological phenomena, such as the condensation and packaging of DNA, ion transport across cellular membranes and the enzymatic action of proteins, rely on the complex interplay between nanoscale electrostatic, osmotic...
As fourth-generation synchrotron x-ray sources start to come online, they bring with them the promise of increased imaging speed and resolution for current imaging modalities, while enabling entirely new ones. Employing the increased brightness at hard x-ray energies begins with having efficient focusing optics in place. Zone plates are popular...
Nuclear magnetic resonance (NMR) measurements have been performed on the heavily Cu-doped ($x = 0.13$, 0.18, 0.24, 0.39, 0.48), and underdoped (x = 0.01 and 0.012) \NaFeCuAs~ single crystals, to reveal the nature of the magnetism, and to investigate how the electronic and magnetic properties of the system evolves with...
Valence-to-core (vtc) x-ray emission spectra (XES) provides direct information on occupied valence orbitals and is sensitive to chemical environment. Combining with element specificity and high penetration of hard x-rays, it is emerging as an information-rich technique and its applications have been demonstrated in research fields, such as catalysis and metalloenzymes....
I present the body of work I have pursued over the course of my doctoral study at Northwestern University. First, I conduct an analysis of the measurement abilities of distinctive LISA detector designs, examining the influence of LISA's low-frequency performance on the detection and characterization of massive black hole binaries....
The field of time-domain astronomy has seen significant advancements in the latest years as increasingly sensitive, deep and wide-field surveys of the sky at all wavelengths are being carried out more and more frequently. Furthermore, the addition of gravitational wave detectors around the world has opened an entirely new window...
Optical interferometers and resonators are commonly used for precision measurement. These devices can accurately measure the phase shifts of light induced by small changes in the optical path in the device. To meet the need for ultra-sensitive measurement, researchers have developed various approaches to build better and more sensitive devices....
The pp → W + W − process is important as it allows the test of electroweak theory. Mea-surements of this processes have lead to reduced uncertainties on many other processes one
of which being the Higgs. There have been discrepancies between predicted and measured
cross-section values for pp →...
Due to the unprecedented sensitivity of the Advanced LIGO--Virgo network, in less than ~5 years the field of gravitational-wave astrophysics has evolved from speculating about the properties of compact binary mergers to having an observed population that facilitates astrophysical inference. These observations encode information about their progenitor stellar systems ---...
Quantum metrology has been among the most vigorous branches of quantum technology. It involves using quantum effects to achieve better estimation of parameters of a physical sys- tem. Conventionally the system consists of an ensemble of N non-interacting atoms and the measurements are done on individual atomic states, such as...
This thesis focuses on exploring the explanatory and discovery potential of the four-neutrino and enhanced neutrino magnetic and electric dipole moments hypotheses when
applied to the NOvA/T2K discrepancy and the XENON1T anomaly, respectively. Firstly,
we study the effect of a very light (sub eV) sterile neutrino on the NOvA/T2K anom-...
Nonlinear systems with many interacting components often exhibit behaviors that cannot be anticipated, even in principle, by only knowing the properties of the constituent parts and thereby emerge as a result of interactions between the parts. Examples of such systems range from power grids and financial markets to food networks...
Metallic conductivity and broken inversion symmetry were long thought to be contraindicated properties, under the assumption that long-range Coulombic interactions (screened by free charge carriers) were necessary for coordinated polar displacements. Within the past decade, the discovery of polar metals has prompted a rethinking of the relationship between metallicity and...
Superconducting-circuit based platforms are strong contenders in the race to build a quantum computer.While the transmon has had extraordinary success as the leading superconducting qubit modality, there are reasons to believe that other types of qubits could possess relative benefits in terms of noise immunity, anharmonicity, or extensibility. In this...
This thesis describes the synthesis and photophysical characterization of low-dimensionalmaterials—including thin-film semiconductors, colloidal quantum dots, and molecules—with the
broader motivation of integrating them into mixed-dimensional heterostructures with novel
responses to external stimuli. Due to their high surface area to volume ratio and incomplete
dielectric screening, mixed-dimensional heterostructures have high sensitivity...
New capabilities in x-ray microscopy have been enabled by rapid advances in synchrotronlight sources and in high performance computing. We present here conceptual and computational
advances in two areas of x-ray microscopy. One involves ptychography, where computation is
used to obtain images from diffraction patterns as a finite coherent illumination...
From the early usage of metallic thin films as mirrors tracing back to 2900 BC, to the modern thin film photonic circuits as a mature optical processing platform, and to the growing class of atomically-thin two-dimensional (2D) materials with diverse and tailorable properties, thin film materials have played an important...
Since the dawn of mankind, humans have used materials and tools to dominate the world. As our understanding of the fields physics, chemistry and engineering is growing, we are able to artificially create advanced materials with engineered responses. Next step would be to create ‘ smart’ or intelligent materials capable...
Although flowing granular materials have been formally studied for over two hundred years, their behavior is still poorly understood relative to fluids, solids, and gases. Sheared granular materials with differing particle properties (e.g., size, density, shape) segregate (de-mix) due to percolation (small particles fall between large ones) and buoyancy (light...
I present concepts and methods for evaluating infrared camera systems. The individual components of camera systems are fairly well understood, but the system is more than the sum of its parts. Many of the usual techniques for measuring individual photodetectors are inapplicable to pixels which are permanently bonded to a...
In this dissertation, I summarize my findings of the dynamics of colloidal suspensions over a large range of volume fractions in two systems: drop impact and film rupture. The existence of a deformable surface in both these systems allows me to capture the consequences of non-Newtonian flow using high-speed imaging....
Understanding how spin waves propagate through ferromagnets is an important component of a wider international effort to create spintronic devices. In this thesis, we develop a propagating spin wave spectroscopy to make a variety of measurements on thin films of Yttrium Iron Garnet (YIG), a material known for having long...
How molecular chirality manifests at the nano- to macroscale has been a scientific puzzle since Louis Pasteur discovered biochirality. In general, amphiphilic molecules can organize into a variety of assembly shapes including micelles, spherical vesicles, cylindrical micelles, and planar bilayers. However, when such amphiphilic molecules are chiral, helical ribbons, helicoidal...
The three-dimensional (3D) nanoscale structure of III-As nanowires is correlated with optical and electronic property measurements to deconvolve the contributions of strain, composition, and crystal structure to characteristics of interest for future electronic and optoelectronic devices. Multiple advanced two-dimensional (2D) and 3D characterization techniques are employed such as atom probe...
Although electrostatics interactions in fluids have been studied for many decades, new results in this field are still challenging our classical understanding of electrolytes. The combination of electrostatics and self-assembly yields many interesting yet challenging problems that are of fundamental scientific interest and show promise for industrial applications. In this...