School of Physics - Theses
Now showing items 1-12 of 191
Practical Aspects of the Preparation of NV Centers In Diamond for Quantum Applications and Magnetometry
This thesis present the result of four experimental projects, that revolve around the practical aspects of using NV centers for quantum applications. The core of the this work deals with the coherence time of NV centers and how it is affected by damage introduced into the diamond lattice by ion implantation where we have discovered that while the emission of the NV center is sensitive to the damage the coherence time is not. The other topics of this work cover a novel method to deposit isolated nano diamond using aerosols and a method to secure the nano diamonds into silicon substrates using self-assembled mono layers. Finally, the work concludes with a proposal to use the magnetic field produced by spin vortices to increase the coherence time of NV centers where some preliminary result of the spin vortices fabrication are presented.
The host galaxies of high-redshift quasars
In the early Universe, we observe supermassive black holes with masses of up to a billion times the mass of the Sun, accreting at or even above the Eddington limit. These high-redshift quasars are some of the most luminous objects in the Universe, and raise many questions about the formation and growth of the first black holes. Investigating their host galaxies provides a useful probe for understanding these high-redshift quasars. In the local Universe, there are clear correlations between the mass of a supermassive black hole and the properties of its host galaxy, indicating a black hole--galaxy co-evolution. Exploring how these black hole--host relations evolve with redshift can give valuable insights into why these relations exist. Studying the host galaxies of high-redshift quasars thus provides vital insights into the early growth of supermassive black holes and the black hole--galaxy connection. In this thesis I use three techniques to study the host galaxies of high-redshift quasars: the Meraxes semi-analytic model, the BlueTides hydrodynamical simulation, and observations with the Hubble Space Telescope. Meraxes is a semi-analytic model designed to study galaxy formation and evolution at high redshift. Using this model, I study the sizes, angular momenta and morphologies of high-redshift galaxies. I also use Meraxes to study the evolution of black holes and their host galaxies from high redshift to the present day. The model predicts no significant evolution in the black hole--host mass relations out to high redshift, with the growth of galaxies and black holes tightly related even in the early Universe. I also examine the growth mechanisms of black holes in Meraxes, finding that the majority of black hole growth is caused by internal disc instabilities, and not by galaxy mergers. I then use the BlueTides cosmological hydrodynamical simulation to investigate the detailed properties of quasar host galaxies at z=7. I find that the hosts of quasars are generally highly star-forming and bulge dominated, and are significantly more compact than the typical high-redshift galaxy. Using BlueTides I make predictions for observations of quasars with the James Webb Space Telescope, finding that detecting quasar hosts at these redshifts may be possible, but will still be challenging with this groundbreaking instrument. Finally, I use observations from the Hubble Space Telescope to obtain deep upper limits on the rest-frame ultraviolet luminosities of six z~6 quasars. I also detect up to 9 potential companion galaxies surrounding these quasars, which may be interacting with their host galaxies. Observations with the upcoming James Webb Space Telescope are needed to detect quasar host galaxies in the rest-frame ultraviolet and optical for the first time.
Raman spectroscopy of artists' materials: Advances in characterisation and analysis
Cultural heritage research and conservation practice seek to preserve our cultural heritage. Understanding the composition of the materials that comprise the artwork or cultural object is critical to inform collections management and preservation treatments; however methods of analysis are constrained to those that are either non-destructive or can obtain the desired information from micro-samples in order to retain the integrity of the object. Raman spectroscopy is an ideal technique for characterising cultural materials as it is non-destructive, requires relatively little sample preparation and utilises short measurement times. Micro-Raman is especially useful for examining micro-samples and painting cross sections due to its spatial resolution being sufficiently high to target individual pigment grains. Despite the non-destructive, micro-sample analysis advantages, there are limitations to the use of Raman spectroscopy in the cultural heritage conservation context. Firstly, fluorescence is frequently observed in cultural materials. Secondly, with the large number of compositionally complex and heterogenous materials encountered in conservation, there is a need for advanced methods that can deal with large sample datasets. These methods are needed to facilitate examination of both non-spatial data and spatial (imaging) data, to extract the maximum amount of information possible from the limited sample available. It is the aim of this thesis to demonstrate how Raman micro-spectroscopy can provide new and useful information about paintings using the following strategies. (1) Creation of a reliable pigment database supported by X-ray diffraction data to confirm the structural identity of each pigment. At the time this work was started, a spectral library for pigment identification was necessary to have a comprehensive set of pigment reference spectra against which to compare unknowns. A Raman spectral pigment reference library was developed comprising over 180 samples from the National Gallery of Victoria’s pigment collection. Samples were validated using X-ray Powder Diffraction (XRPD) prior to Raman analysis. This Raman spectral pigment library can also support future identification of materials and artworks, alongside other Raman spectral databases that are now available. (2) Utilisation of the database in conjunction with longer wavelengths to mitigate fluorescence effects. In the presence of fluorescent components, Raman analysis is hampered. To mitigate the impact of fluorescence observed at 514nm, the efficiency of 830nm wavelength incident irradiation was examined. It was found effective and used to answer five research questions (case studies) regarding authenticity and art historical practice and to inform attribution, provenance studies and conservation treatments: a) Mock-up paintings were prepared to trial the experimental methodology. The overpaint in a 16th century portrait miniature was identified as Zinc white pigment, indicating the overpaint was applied after the mid-19th century. b) An Australian Impressionists artist’s catalogue from 1889 was examined and the inks found to contain Prussian blue and vermilion as the main pigments, with a minor addition of minium and perhaps a lake pigment, providing insight into the artist’s technical methods. c) Overpainted cracks in Tom Roberts’ iconic painting Shearing the Rams were suspected to have been due to the type of pigment used. The main pigment was vermilion, which is not known to cause cracking, so the cause of cracking is now believed to be due to the high ratio of binding medium in the paint. d) The Finding of Moses (1712) was reattributed to Giambattista Tiepolo (1696-1770), after Prussian blue was identified as a key component of the paint layer. e) The organic blue colour in an Indian Palampore was dissimilar to indigo but matched a published spectrum of indigo on silk, highlighting the importance of local structure and bonding on subtle features in Raman spectra. (3) Identified a practical method of Surface Enhanced Raman Spectroscopy for conservation to increase the Raman signal and make it visible over the photoluminescent background. This work reviewed several SERS substrate configurations, then prepared and evaluated SERS substrates prepared by a) colloidal Ag nanoparticles, b) Ag coated nanospheres, c) Ag foil etching and d) electroless deposition of Ag on a Cu coupon. The ease of production and reproducibility were used to select the most practical substrate for SERS analysis in conservation being SERS substrates prepared using an electroless deposition method. The selected substrate was used to identify dammar as the varnish used on an important Italian Renaissance painting by Tiepolo with the outcomes published in 2008. (4) Developing new methods of data analysis for managing complexity in spectra and large data sets. Multivariate analysis techniques have been used to analyse spectral datasets in numerous fields and provide an excellent opportunity to enhance the analysis of large Raman spectra datasets in conservation. Principal components analysis (PCA) and hierarchical clustering analysis (HCA) methods were used to visualise the data structural relationships amongst Raman spectra of natural and synthetic resins. It has been demonstrated that the two most utilised natural resins, dammar and mastic, are able to be distinguished from one another by PCA and HCA of their Raman spectra, irrespective of their supplier and the naturally occurring sample variance. This work also shows, using PCA and HCA, that the synthetic cyclohexanones resins Ketone N and Laropal K 80 are indistinguishable whilst the other synthetic painting varnish cyclohexanone, MS2A, is easily separable. The synthetic resins were found to be quite homogeneous in composition with little variability in their Raman spectral response compared to a very much greater degree of variance was observed within the natural resins: amber, copal, colophony and sandarac. Finally, a multivariate image analysis method, assembling the data into a 3D data-cube and using PCA and clustering techniques, was developed. The method for assembling and analysing the spectral 3D data cubes was achieved using prepared samples of known pigments in binder. The technique was used in the analysis of an Italian renaissance painting. PCA and clustering methods were applied to SEM-EDS elemental maps of Ti, Sn, Si, Pb, Mn, Mg, K, Fe, Cu, Ca, Al, S (corrected for Pb) and O, to develop a compositional map of the materials used and indicate their sequence in the layered construction of the painting. Secondly, using Raman maps of spectral intensity collected at 830 nm to mitigate fluorescence, and using the spectral database, vermilion, lead-tin yellow type 1 and a blue-green pigment consistent with terre-verte or another green silicate pigment were found in the paint layer. The ground layer was found to contain anhydrite with large gypsum inclusions. The identification of these components has led to the attribution of a previously anonymous painting to Dosso Dossi with the outcomes published in 2008, receiving 70 citations until 2019. Multivariate methods developed here have been further applied in published research in both conservation and non-conservation applications, which is noted in this thesis.
A measurement of E-mode polarisation spectrum of the cosmic microwave background with the POLARBEAR experiment
The cosmic microwave background (CMB) stands as one of the most interesting subjects of astronomical surveys. The CMB light carries information about the history and the origin of the universe. Polarisation of the CMB can be decomposed and transformed in to E-mode and B-mode polarisation. My thesis focuses on the measurement of E-mode polarisation power spectrum of the cosmic microwave background using 150 Ghz data taken from July 2014 to December 2016 with the POLARBEAR experiment. POLARBEAR is an on-going cosmic microwave background experiment that began taking data in 2012. The target area of observation for the data in this thesis is a large patch of sky of over 600 deg2. A continuously rotating half wave plate was installed in the POLARBEAR telescope and heavily influences the overall data analysis. This thesis is outlined as followed. Chapter 1 reviews the standard model of cosmology, and explain the physics of the CMB and CMB polarisation. Chapter 2 describes the POLARBEAR experiment. Chapter 3 gives a brief review of the continuously rotating half wave plate and its impacts on recorded data. Chapter 4 describes the calibration of the recorded data. Chapter 5 describes the pipeline to process the recorded data. Chapter 6 details on the validation of the established power spectrum pipeline, the data selected following Chapter 5, and the estimation of systematics in POLARBEAR data. Chapter 7 details on the E-mode power spectrum estimated from the selected data. I use the measured E-mode power spectrum in combination with other data sets: Planck 2018, ACTPol, SPT-SZ, and BAO data to constrain cosmological parameters. The combined data set is consistent with the standard Lambda Cold Dark Matter model of cosmology. I also consider extensions to the standard model, and present improved constraints on these extensions. Chapter 8 summaries preceding chapters and gives an outlook on the Simons Array, the successor of the POLARBEAR experiment.
Learning invariant representations with applications to high-energy physics
In searches for new physics in high-energy physics, experimental analyses are primarily concerned with physical processes which are rare or hitherto unobserved. To claim a statistically significant discovery or exclusion of new physics when studying such decays, it is necessary to maintain an appropriate signal to noise ratio. This makes systems capable of efficient discrimination of signal from datasets overwhelmingly dominated by background events an important component of modern experimental analyses. However, na\"ive application of these methods is liable to raise poorly understood systematic effects which may ultimately degrade the significance of the final measurement. To understand the origin of these systematic effects, we note that there are certain protected variables in experimental analyses which should remain unbiased by the analysis procedure. Variables that the input parameters of models of new physics are strongly dependent upon and variables used to model background contributions to the total measured event yield fall into this category. Systems responsible for separating signal from background events achieve this by sampling events with signal-like characteristics from all candidate events. If this procedure introduces sampling bias into the distribution of protected variables, this introduces systematic effects into the analysis which are difficult to characterize. Thus it is desirable for these systems to distinguish between signal and background events without using information about certain protected variables. Beyond high-energy physics, building systems that make decisions independent of certain protected or sensitive information is an important theme in the real-world application of machine learning and statistics. We address this task as an optimization problem of finding a representation of the observed data that is invariant to the given protected quantities. This representation should satisfy two competing criteria. Firstly, it should contain all relevant information about the data so that it may be used as a proxy for arbitrary downstream tasks, such as inference of unobserved quantities or prediction of target variables. Secondly, it should not be informative of the given protected quantities, so that downstream tasks are not influenced by these variables. If the protected quantities to be censored from the intermediate representation contain information that can improve the performance of the downstream task, it is likely that removing this information will adversely affect this task. The challenge lies in balancing both objectives without significantly compromising either requirement. The contribution of this thesis is a new set of methods for addressing this problem. This thesis is divided into two parts, which are largely independent of one another. The first part of this thesis is about constraining the optimization procedure by which the representation is learnt to reduce the informativeness of the representation of the given protected quantities, such that the representation is invariant to changes in these quantities. The second part of this thesis approaches the problem from a latent variable model perspective, in which additional unobserved (latent) variables are introduced which explain the interaction between different attributes of the observed data. These latent variables can be interpreted as a more fundamental, compact lower-dimensional representation of the original high-dimensional unstructured data. By constraining the structure of this latent space, we demonstrate we can isolate the influence of the protected variables into a latent subspace. This allows downstream tasks to only access a relevant subset of the learned representation without being influenced by protected attributes of the original data. The feasibility of our proposed methods is demonstrated through application to a challenging experimental analysis in precision flavor physics at the Belle II experiment - the study of the $b \rightarrow s \gamma$ transition, a sensitive probe of potential new physics.
Distributed Matrix Product State Simulations of Large-Scale Quantum Circuits
Before large-scale, robust quantum computers are developed, it is valuable to be able to classically simulate quantum algorithms to study their properties. To do so, we developed a numerical library for simulating quantum circuits via the matrix product state formalism on distributed memory architectures. By examining the multipartite entanglement present across Shor’s algorithm, we were able to effectively map a high-level circuit of Shor’s algorithm to the one-dimensional structure of a matrix product state, enabling us to perform a simulation of a specific 60 qubit instance in approximately 14 TB of memory: potentially the largest non-trivial quantum circuit simulation ever performed. We then applied matrix product state and matrix product density operator techniques to simulating one-dimensional circuits from Google’s quantum supremacy problem with errors and found it mostly resistant to our methods.
Measurement of Direct CP Asymmetry and Branching Fraction in B0→D0𝜋0 and B+→D0𝜋+ at the Belle Experiment
This thesis describes the measurement of direct CP asymmetry and branching fraction for the hadronic B decays B0 -> D0 pi0 an B+ -> D0 pi+. The study uses the full dataset of 711 fb^(-1) collected at the Y(4S) resonance by the Belle experiment at the KEKB accelerator in Tsukuba, Japan. Event reconstruction, background suppression and modelling are first studied using Monte Carlo simulations, before yield and direct CP asymmetry are extracted in a three-dimensional unbinned extended maximum likelihood fit. B+ -> D0 pi+ is measured first as the control mode to validate the methodology, before same techniques are used on B0 -> D0 pi0 . The measured branching fractions and direct CP asymmetries are: Br(B0 -> D0 pi0) = (2.69 +/- 0.06 +/- 0.09) x 10^(-4), A_CP(B0 -> D0 pi0) = (0.10 +/- 2.05 +/- 1.29) x 10^(-2), Br(B+ -> D0 pi+) = (4.53 +/- 0.02 +/- 0.14) x 10^(-3), A_CP(B+ -> D0 pi+) = (0.19 +/- 0.36 +/- 0.60) x 10^(-2), for B0 -> D0 pi0 and B+ -> D0 pi+ respectively, where the first uncertainty is statistical and the second is systematic. The represents the world’s first measurement of direct CP asymmetry for B0 -> D0 pi0. This measurement of branching fraction of B0 -> D0 pi0 and B+ -> D0 pi+, and direct CP asymmetry of B+ -> D0 pi+ are the most precise to date, and consistent with the current world average values.
Weighing the Giants: Measuring galaxy cluster masses with CMB lensing
Galaxy clusters are powerful probes of cosmology. Their abundance depends on the rate of structure growth and the expansion rate of the universe, making the density of clusters highly sensitive to dark energy. Galaxy clusters additionally provide powerful constraints on matter density, matter fluctuation amplitude, and the sum of neutrino masses. However, cluster cosmology is currently limited by systematic uncertainties in the cluster mass estimation. Generally, the cluster masses are estimated using observable-mass scaling relations where the observable can be optical richness, X-ray temperature etc. The observable-mass scaling relation depends on the complex cluster baryonic physics which is not well understood and any deviation in the baryonic physics will lead to uncertainties in the mass estimation. On the other hand, gravitational lensing offers one of the most promising techniques to measure cluster mass as it directly probes the total matter content of the cluster. Gravitational lensing can additionally be used to calibrate the observable-mass scaling relations. The gravitational lensing source can either be optical galaxies or the cosmic microwave background (CMB). My thesis focuses on developing statistical and mathematical tools to robustly extract the cluster lensing signal from CMB data. We develop a maximum likelihood estimator to optimally extract cluster lensing signal from CMB data. We find that the Stokes QU maps and the traditional EB maps provide similar constraints on mass estimates. We quantify the effect of astrophysical foregrounds on CMB cluster lensing analysis. While the foregrounds set an effective noise floor for temperature estimator, the polarisation estimator is largely unaffected. We use realistic simulations to forecast that CMB cluster lensing is expected to constrain cluster masses to 3-6%(1%) level for upcoming (next generation) CMB experiments. One of the standard ways to extract the CMB-cluster lensing signal is by using the quadratic estimator. The thermal Sunyaev-Zel'dovich effect (tSZ) acts as a major contaminant in quadratic estimator and induces significant systematic and statistical uncertainty. We develop modified quadratic estimator to eliminate the tSZ bias and to significantly reduce the tSZ statistical uncertainty. Using our modified quadratic estimator we constrain the mass of Dark Energy Survey year-3 cluster catalog. We also put constraints on the normalisation parameter of optical richness-mass scaling relation. In addition to removing the tSZ bias, modified quadratic estimator also reduces tSZ induced statistical uncertainty by 40% in future low noise CMB-surveys.
Quantum hyperpolarisation of nuclear spins and multi-modal microscopic imaging with diamond defect spins
Quantum technologies promise to impact on several aspects of society. Examples include quantum computing to perform certain calculations significantly faster than current classical computers, quantum cryptography for more secure communications, quantum sensing to make measurements with unprecedented sensitivity and resolution, and specialised quantum devices such as quantum hyperpolarisers for enhanced medical imaging. However, the field is still in its infancy and most quantum technologies have been realised only in delicate laboratory settings with little prospect for real-world applications (e.g. quantum sensors), or are many years away from being mature enough to make an impact (quantum computing). This thesis develops two applications of quantum technologies, in the direction of quantum hyperpolarisation on the one hand and quantum sensing on the other hand, which utilise a quantum system particularly suited for practical applications, the nitrogen-vacancy (NV) centre in diamond. This diamond spin defect can be operated in ambient conditions and the resulting quantum devices can be easily miniaturised for large scale deployment. Specifically, in the first part of this thesis (chapters 2 to 4), two new techniques to realise hyperpolarisation (HP) of nuclear spins are developed. Through effective HP, ensembles of nuclear spin can be polarised far beyond the normal Boltzmann level, which can be used to enhance the spin signal for nuclear magnetic resonance (NMR) and imaging (MRI). Chapter 2 and 3 focus on exploiting direct cross-relaxation (CR) between the NV spin and the nuclear spin. Chapter 2 investigates a CR-based protocol for sensing, and determines, through a study of the NV physics, under what regimes this protocol can be applied to nuclear spin detection. This study constructs a framework under which HP via CR can be realised. Chapter 3 continues in this direction and demonstrate that CR can be used to hyperpolarise external nuclear spins. A detailed understanding of the spin bath mechanics is explored and the impact of rogue uncontrolled NV spins on this spin bath is determined. Additionally, this protocol is compared with other HP techniques and shows a remarkable improvement in polarisation rate, however, it is particularly sensitive to magnetic field detuning. To overcome this issue, in chapter 4 a different technique is developed that relies on a dynamical decoupling protocol purposefully modified to achieve HP. This new technique has a slower polarisation rate than CR-based HP but is robust to the experimental errors that exist in scaling these hyperpolarisation techniques. The second part of this thesis (chapters 5 and 6) exploits the quantum sensing properties of ensembles of NV centres in diamond to develop multi-modal microscopic imaging, which is a promising tool for device diagnosis and the study of mesoscopic phenomena. Specifically, chapter 5 develops and implements a technique for imaging the electric field simultaneously with the magnetic field. The technique is applied to the study of electric fields that are intrinsic to interfaces and junctions. The functionality of electronic devices (such as transistors) are fundamentally dictated by these fields which have traditionally been opaque to probing except at the very surface. While the surface potential is crucial, a wealth of information is contained in the bulk structure which is the focus of this study. In chapter 6 the same sensing protocol is extended to image stress embedded in the diamond rather than electric fields. A series of different deformation sources is used to test and verify that the technique can determine the entire stress tensor with high sensitivity and micrometer spatial resolution. With these new imaging capabilities, extending the traditional magnetic field sensing to electric field and stress, multi-modal NV imaging is a promising example of quantum technology that may have an immediate impact in other fields of science.
Bioelectronic systems enabled by wireless electromagnetic power transfer
Wireless biomedical electronic implants are rapidly being developed to treat a variety of medical conditions. Current technologies include the pacemaker to treat arrhythmias, the cochlear implant to overcome hearing impairment and the deep brain stimulator to treat Parkinson’s disease. Researchers are aiming to create implants that are miniaturised, battery-free, and minimally invasive. This is to ensure that devices are simpler to implant, to avoid surgical battery replacement and to minimise the risk of infection. To meet these demands, future biomedical electronic implants need to be miniaturised and capable of wireless power and data transfer. This thesis explores and extends the capabilities of three different wireless power transfer technologies for biomedical electronic implants: inductive, capacitive and radiative power transfer. This thesis adopts a systems approach to extend the capabilities of wireless power transfer systems. Wireless inductive power transfer has received thorough attention in the literature and involves the use of time-varying magnetic fields to transmit power through biological tissue. Typically, inductive power transfer involves a single transmitter and single receiver. This thesis demonstrates many receiving devices can be operated from a single transmitter - without adding complicated electronics to each receiving device. Moreover, by tuning the receiving coil on each device carefully the transmitter can power individual devices, or multiple devices simultaneously, extending the capabilities of inductive power transfer systems. Optogenetics, a technique used to transfect cells to make them light sensitive, is used to provide biological validation of the multichannel inductive receiving topology. Human embryonic kidney cells are transfected to be sensitive to blue light and then a twin channel inductive receiver with a blue and yellow light is modulated to demonstrate a cell response and no cell response respectively. Inductive coupling is not always the most suitable power transfer scheme and wireless capacitive coupling is presented as an alternative. This is where time-varying electric fields transmit power through biological tissue via conductive plates. Stenting, a surgical procedure used to prevent blood vessels from closing, is used to validate the efficacy of capacitive coupling in a biological context. Stents are thin metal tubes resembling chicken wire made from nitinol - a conductive nickel titanium alloy. There is significant motivation to include intelligent sensors in stents as they are simple to implant via angiographic catheter. However, stents preclude the use of batteries as they cannot be removed after surgery so wireless power and data transfer is essential. The optimal frequency to use to transmit power to a stent via capacitive coupling is derived from first principles. Then, a miniaturised circuit board, capable of wireless power and data transmission is fabricated and placed between two stents. The wireless power and data transfer capabilities of the device are validated in-vitro in excised muscle tissue and in-vivo in a live ovine model. The results demonstrate that capacitive power and data transfer is viable for stent-based biomedical implants. An emerging area of study is wireless radiative power transfer through biological tissue. Such a technique is promising for powering miniaturised, deep tissue implants. Due to the dispersive nature of biological tissue, finite element analysis is essential to understanding how wireless radiative power transfer can power biomedical electronic implants efficiently. This thesis builds on efficient radiative power transfer schemes by proposing a new implant and antenna geometry. Long and thin implants show promise as they have the potential to be delivered by catheter or injection - reducing surgical risk and overhead. This thesis demonstrates a technique that uses near-field radiative power transfer to efficiently power a 20 mm long implant that is sub-millimetre in diameter. To power the device, optimised wide dipole transmitting antennas are simulated, designed, fabricated, tested and measured for various implant depths. Biological validation is provided by stimulating retinal ganglion cells wirelessly with the miniaturised device designed to power a small light. In summary, the work presented in this thesis demonstrates that by extending wireless powering schemes from the well known inductive coil to include capacitive and radiative power transfer, implants can be miniaturized and inserted in places in the body that might have not seemed previously possible. Therefore, wireless biomedical electronics implants are likely to become miniaturised, battery-free and ubiquitous. Whilst these techniques may offer significant economic and health benefits, there are also complicated ethical questions to consider. With the promise of pervasive, safe, minimally invasive and battery free biomedical electronic implants, humans will have the choice to enhance their abilities. Naturally, the question of what it means to be human will emerge.
Nature of quasar disk-wind
The brightest persistent astrophysical sources in the universe are quasars, a group of active galactic nuclei (AGN) that appear star-like and radiate across all wavelengths. The emitted radiation is believed to be powered by a supermassive black hole at the core of a galaxy. Matter that falls into the black hole is being fed onto the accretion disk, heating up the disk in the process due to friction. A wind emanating from the accretion disk, or a disk-wind, appears ubiquitous in these objects and acts as one effective way to generate the spectral lines observed in the quasar's spectrum. The broad spectral lines, originating from the broad line region (BLR), show diverse properties, specifically in velocity shift, line width, and degree of asymmetry. Yet, the exact structure of the BLR has remained perplexing due to its small size, which means it is unresolved even with the current astronomical instrumentation. Thus, simulations are important. By developing a model of the BLR, an informative analysis of the line profiles allows us to explore some of the key questions about the BLR, emphasising the shape of spectral lines, the disk-wind BLR, and the orientation. We simulate line profile modelling using a simple kinematical disk-wind model of the BLR with radiative transfer in the high velocity limit. The model provides a framework to explore the characteristics of the emission line profile induced by the different geometries and kinematics of the BLR, including the opening angle of the wind and the geometry of the line emitting region. The effect of orientation in these systems is also examined. As a first step, we use the model to simulate a narrow outflowing disk-wind, which has been described in the literature. The primary objective is to determine whether the observed emission line properties are consistent with a narrow wind scenario. We find that the line profiles are more blueshifted for a narrow polar wind model as opposed to intermediate and equatorial models. When viewing at pole-on angles, the simulated emission lines show a narrower line width, which is asymmetric and more blueshifted than that viewed edge-on. The blueward shift of the line profile increases as the line-of-sight and wind intersect. The model is also able to recover a shorter time delay in the red or blue side of the line profiles, consistent with observational evidence in reverberation mapping studies. The second part of the thesis considers the properties of broad absorption line quasars (BALQs). These objects are rare and often display a blueward absorption trough relative to the emission line. One interpretation of the velocity offsets is the unification based on orientation, whereby a BAL is viewed within a constrained narrow wind angle. In order to test whether the BALQs and non-BALQs can be distinguished by their emission features, we conduct statistical tests and machine learning on the two populations. We find that their continuum and emission features are qualitatively similar, which contradicts the narrow disk-wind model in the geometric unification. Therefore, we propose a model of the disk-wind comprising a wide wind opening angle with multiple dense radial streams, where the BAL is detected when the line-of-sight crosses these streams. These findings have lead us to the discovery of a novel orientation indicator of quasars in the ultraviolet-optical regime. We propose a simple yet robust angle-of-viewing probe using the correlation between the velocity shifts and line widths. Our idea is shown to be qualitatively consistent with other orientation proxies. We also perform a wide angle disk-wind simulation and successfully retrieve the predicted correlation with inclination. In addition, we extend our model to estimate the bias in the virial black hole mass due to the scale factor f, which is related to the unknown nature of the BLR. Using a wide disk-wind configuration, we retrieve the f factors for a range of inclination angle. The f factor shows significant dependence with orientation, characterisation of the line width, and location of the emission region in the wind. Therefore, using a constant f value biases the estimation of the mass of the black hole.