Physics Commons^™

Fabrication Of Objectives For Imaging Ultracold Lithium, Danelle Akanova

Dartmouth College Master’s Theses

This thesis develops a documented, reproducible procedure for building diffraction-limited microscope objectives entirely from catalog singlets, for imaging ultracold 6Li atoms in a ring-trap experiment. The objectives must resolve micron-scale features through a 5 mm fused-silica vacuum window, operate at multiple wavelengths, fit inside a 48 mm magnet bore, and contain no conductive or magnetic material, because the surrounding coils switch 0.1 T fields on microsecond timescales. Commercial long-working-distance objectives are universally housed in metal, which the eddy-current constraint rules out, and custom fabrication of a suitable non-conductive matched pair is estimated at nearly $200k.

The procedure is developed and …

Electronic Structure Discretization And Compression Using Diagonal Basis Sets, Casey Lee Dowdle

Dartmouth College Ph.D Dissertations

Numerically solving the electronic structure problem is a fundamentally difficult problem due to the exponential growth in the dimension of the Hilbert space as the system size increases. In order to solve problems at a chemically relevant accuracy, both the choice of basis set and numerical method are important factors that are intrinsically connected.

In this thesis, we study the discretization and resulting compression of electronic Hamiltonians using diagonal basis sets. A diagonal basis set approximately diagonalizes the matrix and tensor representations of the one- and two-body potentials. This can reduce storage, simplify matrix-vector products, and lower the complexity of …

Behavior Of Magnetic Reconnection In The Relativistic Regime Under The Presence Of Shear Flows And Guide Field, Sarah Peery

Dartmouth College Ph.D Dissertations

Magnetic Reconnection is a ubiquitous phenomenon in plasma, where magnetic energy is released into plasma thermal and kinetic energy through the rearrangement of magnetic topology. In this study we derive fluid scaling models to predict the steady state and onset behavior of magnetic reconnection in the highly magnetized (relativistic) regime, in the presence of plasma shear flows and a (out-of-plane) guide field. We use 2.5D kinetic particle-in-cell simulations to motivate and validate these models. We find that, similar to the non-relativistic regime, shear flows parallel to the reconnecting magnetic field will delay reconnection onset and slow outflow jets. They can …

Hot Jupiter Atmospheres Through Time, Annabelle E. Niblett

Physics and Astronomy Undergraduate Senior Theses

Transmission spectroscopy of hot Jupiters enables mass and atmospheric composition measurements, providing insight into population dynamics and evolution when other methods are hindered by stellar activity. To effectively plan observations and interpret transmission spectra, we must have a robust understanding of how atmospheres evolve over time. To that end, we present a suite of hot Jupiter transmission spectra models with ages ranging from 3 Myr to 11 Gyr. We incorporate the cooling and contraction of the planet, which impacts the atmospheric profile, and the evolution of the stellar UV spectrum, which moderates photodissociation and photoionization. Using PICASO,  VULCAN, and FastChem …

Investigating Broadband Plasma Waves As A Driver Of Radiation Belt Energetic Electron Loss To Earth's Atmosphere, Lauren Zanarini

Physics and Astronomy Undergraduate Senior Theses

Wave-particle interactions play a central role in transferring energy between different particle populations in space plasmas. In the radiation belts, these interactions govern the acceleration, scattering, and loss of energetic particles to Earth’s atmosphere. Understanding the drivers of these energetic particle losses is essential, as these particles can collide with satellites and contribute to ozone depletion as they enter the atmosphere. Developing a clearer picture of these processes will improve our ability to predict radiation belt variability and quantify the impacts, ultimately allowing us to mitigate the adverse effects.

Previous research has identified wave modes important for scattering electrons into …

Pedersen By Proxy: Neutral Wind Drivers Of The Magnetosphere, Shreya Gandhi

Physics and Astronomy Undergraduate Senior Theses

Measurements of Saturn’s radio and magnetic periodicities suggest that atmospheric forcing influences the magnetosphere-coupled current systems on the planet (Gurnett et al., 2007). A proposed mechanism for this phenomenon is that thermospheric heating drives strong neutral winds which drag ionospheric plasma and generate currents that close along magnetic field lines (Smith, 2011). However, the local current-closure physics of these processes is di!cult to isolate in global Saturn models even if they suggest neutral wind forcing is a plausible driver for these changes (Jia et al., 2012). This thesis uses the Earth-based auroral GEMINI (Geospace Environment Model of Ion-Neutral Interactions) model …

Tracing The Seam: Machine Learning Models Of The Open–Closed Boundary From Upstream Solar Wind Drivers, Arnav Singh

Physics and Astronomy Undergraduate Senior Theses

The open–closed magnetic field line boundary (OCB) demarcates closed terrestrial field lines from those threaded into the interplanetary medium, and its latitude encodes the instantaneous balance between dayside and nightside reconnection that governs much of the high-latitude space-weather hazard. No single instrument resolves it globally in real time. In this thesis I close that gap empirically. Pairing nearly three decades (1983–2012) of Defense Meteorological Satellite Program particle-precipitation boundaries with the 5-minute OMNI solar-wind and geomagnetic-index record yields ∼9.1×10⁵ causally matched crossings, partitioned into six hemispheric/MLT sectors after a |MLat| ≥ 40° physics cut.

On this corpus I train three …

Classical Motion Of Bounded Orbits In Two-Body Problems, Dina F. Stein

Physics and Astronomy Undergraduate Senior Theses

The study of bounded and periodic motion in classical systems is of central importance in celestial mechanics, atomic models, and the theory of integrable systems. Central-force problems are of particular importance due to their rich geometric structure and the existence of conserved quantities that strongly constrain orbital behavior. In this thesis, we investigate the classical motion of bodies subject to two central-force potentials: the inverse-square and the pseudo-harmonic. For each system, explicit solutions for the radial and angular equations of motion are derived and analyzed. The resulting trajectories are classified according to whether they are bounded, unbounded, open, closed, or …

Measuring Modulation Envelope Of A Pound Drever Hall Feedback Loop, Josh S. Lee

Physics and Astronomy Undergraduate Senior Theses

From improving qubit readout to real world medical technology, fast and ultrasensitive electrometry has many real world applications. The primary goal of the overarching project is to improve ultrasensitive charge detection using methods involving cavity-embedded Cooper pair transistor (cCPT) devices. This project hopes to accomplish this by using the gate-tunability of the cCPT to reduce the 1/f-noise, a type of low-frequency noise that can interfere with the cCPT’s measurement operability. By using a Pound-Drever-Hall (PDH) feedback loop-inspired scheme that can adjust the cCPT gate, this project hopes to improve the stability of the cCPT’s resonant frequency against the 1/f-noise, in …

Effects Of Coulomb Collisions On The Structures Of Fast Magnetosonic Shocks, Bo Farnell

Physics and Astronomy Undergraduate Senior Theses

We present fully kinetic particle-in-cell simulations demonstrating qualitative effects of binary Coulomb collisions on fast magnetosonic shocks. We find that with a sufficiently high collisional frequency, shock rippling and reformation can be inhibited, creating stationary, laminar shocks. We see that collisions rapidly bring the reflected population into equilibrium with the upstream population, adding credibility to existing theories that the separation of these two populations create these dynamical behaviors around the shock transition region. We also see that Ohmic heating from Coulomb collisions can suppress instabilities.

Modeling Velocity Distributions Of Interstellar Neutral Hydrogen In The Heliosphere, Lucas Robert Dyke

Dartmouth College Ph.D Dissertations

As interstellar neutral hydrogen (ISN H) is the most abundant neutral element in the helio- sphere, the region within which the solar wind interacts with the portion of the interstellar medium through which our solar system moves through, it is integral that we aim to under- stand its many properties and interactions within this region. This work details the synthesis and use of a model of ISN H, using trajectory methods to backtrace from a target point at a radial distance of 1 au where explorer probes like Interstellar Boundary Explorer (IBEX) and Interstellar Mapping and Acceleration Probe (IMAP) reside. …

Dynamics Of Localized Wave Packets In Quantum Mechanics, Ayla Zook, Keigo L. Fujita, Rufus Boyack Phd

Wetterhahn Science Symposium Posters

Quantum wave packets are localized, time-dependent solutions of the Schrödinger equation that mimic classical particle motion. In his 1926 paper, Schrödinger famously showed that displacing the ground state of the harmonic oscillator produces a wave packet whose probability density maintains its shape and saturates the Heisenberg uncertainty bound. Motivated by this result, we construct and analyze wave-packet solutions for the Airy potential, the simple harmonic oscillator (SHO), and the pseudoharmonic oscillator (PHO). Our general approach is to find expansion coefficients and take a superposition of the energy eigenstates of the time-independent Schrödinger equation. We examine spatially displaced eigenstates alongside alternative …

In Situ Observations Of Thermal Ions In Perturbed Ionospheres: Techniques And Results, Magdalina Louise Moses

Dartmouth College Ph.D Dissertations

Prediction and mitigation of space weather events are active research topics that require knowledge of the physics governing the ionosphere. Sounding rockets can be used to make in situ observations. The Lynch Rocket Lab created the Petite-Ion-Probe (PIP), a small retarding potential analyzer, to measure thermal ion parameters (i.e., ion density and temperature). A PIP's raw data consists of a series of measured anode currents as a function of screen bias voltages, called IV curves. PIPs can be integrated onto a sounding rocket’s main payload and/or be deployed from the rocket on small platforms called ``PIP-Bobs''. Note that as the …

Basis Design For Electronic Structure And Beyond, Weishi Wang

Dartmouth College Ph.D Dissertations

At the intersection of quantum physics, quantum chemistry, and materials science, electronic structure is the study of electrons in solid-state and molecular systems. Electronic-structure computation relies on discretizing the many-electron Hamiltonian with a finite single-particle basis set. However, basis-set construction is conventionally treated as an ad hoc preprocessing step. This thesis develops an expressive and flexible framework for active, system-oriented basis-set design and numerical modeling strategies that treat basis functions as tunable representations to encode electronic ground-state information.

We first introduce a multi-layered, differentiable basis-construction framework that embeds a set of primitive parameters into mixed-contracted Gaussian-type orbitals. We then develop …

Preliminary Observations From The Relativistic Electron Atmospheric Loss (Real) Satellite Mission, Evzen Selvon, Robyn Millan

Wetterhahn Science Symposium Posters

The Relativistic Electron Atmospheric Loss (REAL) spacecraft (launched in July 2025) is a 3U cubesat designed to measure the precise energies (1 keV – 2MeV) and pitch angles of electrons entering the Earth’s ionosphere. The mission involves Dartmouth, BU, JHUAPL, MSU, and NASA. REAL carries three particle sensors measuring low, medium, and high energies. This work is focused on the ElectroStatic Analyzer (ESA) instrument, designed to measure lower energy electrons (1-40 keV) in the directions parallel and perpendicular to the Earth’s magnetic field. This research aims to identify notable events observed by the REAL spacecraft for future analysis.

Quantum Mechanics As A Framework For Data Assimilation And Its Application To Atmospheric Parameterization, David Freeman

Dartmouth College Ph.D Dissertations

Quantum mechanics, as a mathematical system, can be understood as a generalization of classical probability theory. Quantum Mechanical Data Assimilation (QMDA) is a method in which classical dynamical systems are embedded into a quantum mechanical setting, with an associated data assimilation scheme leveraging the operator algebraic setting. In this dissertation, the algebraic structure underlying the operator theoretic formulation of QMDA is discussed. A procedure for closure of dynamical systems based on QMDA, known as Quantum Mechanical Closure (QMCl), is then constructed, and the procedures for constructing the quantum embeddings and implementing QMCl in practice are laid out and implemented for …

Enhanced Particle Interactions In Highly Curved Spacetime, Bradley Shapiro

Dartmouth College Ph.D Dissertations

Compact objects, such as black holes and neutron stars, are known to be surrounded by dense clouds of particles, including but not limited to photons, various plasmas, and potentially dark matter and gravitons. These environments are of immense research interest, not only for the purpose of understanding the compact objects they surround, but also in the search to identify new particles, especially dark matter. However, certain particle physics calculations are well developed in flat spacetime but intractable in curved spacetime. In this thesis, I present a formalism by which some of these calculations may be made tractable within a perturbative …

Entanglement-Assisted Metrology Under Spatiotemporally Correlated Quantum Noise, Francisco U. Riberi

Dartmouth College Ph.D Dissertations

Quantum sensors operating at the microscale are an emerging branch of quantum technologies where tangible experimental successes have already been reported. State-of-the-art atomic interferometers allow to measure and estimate a variety of physical parameters with unprecedented precision. In principle, exploiting the full power of quantum mechanics would lead to quantitatively better performance bounds over the best possible classical strategies under the same given set of resource constraints. However, the quantum systems' fragility to external disturbances has so far hindered most of these gains to be reached in practice, particularly in the limit of large probe number $N$. Parallel, {\em purely …

Magnetic Reconnection In Space: From Two-Dimensional Magnetohydrodynamic (Mhd) Simulations To Three-Dimensional Particle-In-Cell (Pic) Simulations, Shan-Chang Lin

Dartmouth College Ph.D Dissertations

Magnetic reconnection is a physical process in plasmas that converts magnetic energy into plasma kinetic energy and thermal energy. It plays an important role in the generation of solar flares, interactions between the solar wind and Earth's magnetosphere, and magnetic confinement fusion devices. This thesis focuses on studying magnetic reconnection using computational methods, including two-dimensional (2D) magnetohydrodynamics (MHD) simulations to study Petschek-type reconnection, estimating the timescale from a thin current sheet to fully developed reconnection using 2D particle-in-cell (PIC) simulations, and magnetic reconnection X-line spreading in the current direction using three-dimensional (3D) PIC simulations.

This thesis contributes to the understanding …

Current Continuity In Auroral System Science, Jules Van Irsel

Dartmouth College Ph.D Dissertations

The Earth relies on the Sun's energy, but at times this energy can be overwhelming; the Sun expels plasma which, were it not for our humble magnetic field, would erode our atmosphere (Mars, c. 4 Ga). The protective interaction Earth has with the solar wind results in spectacular auroral displays---one such auroral form is discussed in this thesis: quiet discrete auroral arcs.

Such arcs have long been studied; they are abundant, have usable symmetries, and they can predict magnetic substorms that wreak havoc in our magnetosphere. The auroral emissions, albeit beautiful, are however only the visible end of a self-consistent …

Explorations Of Amplified Feedback In Quantum Circuits, Maxwell B. Weiner

Dartmouth College Master’s Theses

The Josephson Traveling Wave Parametric Amplifier (TWPA) has emerged as a key technology for high-fidelity qubit readout in superconducting quantum computing. By leveraging the nonlinear inductance of an array of Josephson Junctions, the TWPA enables broadband, near-quantum-limited amplification with minimal added noise, significantly improving the signal-to-noise ratio in qubit measurements. Unlike traditional resonant parametric amplifiers, which suffer from bandwidth constraints, the traveling wave design of the TWPA allows for wideband operation, making it particularly suited for multiplexed readout of both simple qubits and large-scale quantum processors.

In this thesis, we explore how the TWPA can be integrated into a feedback …

First-Principles Studies Of Electrical Polarization Effects In Ferroelectrics, Antiferroelectrics And Defects, Louis Alaerts

Dartmouth College Ph.D Dissertations

Over the last few decades, density functional theory (DFT) has emerged as a formidable tool in the field of computational material science. Not only has it become a complementary method approach to experiments by rationalizing the many complex properties of materials but its formidable predictive power can also be used to identify the most promising candidates for specific applications. Point defects in semiconductors have become an important platform for the development of quantum networks due to their ability to act as spin-photon interfaces. Spectral diffusion, the broadening of the optical emission line, can significantly impact the performance of these defect-based …

Quantum Control And Simulation Using Hamiltonian Engineering In Solid-State Nmr, Linta Joseph

Dartmouth College Ph.D Dissertations

Lattices of dipolar coupled nuclear spins in natural crystals are large, interacting quantum systems -- ideal platforms to simulate non-equilibrium many-body dynamics. Using the magnetic resonance toolkit, which includes Dynamic Nuclear Polarization (DNP), Hamiltonian engineering, and multiple-quantum Nuclear Magnetic Resonance (NMR) experiments, we study aspects of coherent control, manipulation, and readout of the complex dynamics of the spin system in NMR quantum simulation.

First, applying Hamiltonian engineering sequences, we control the system evolution. Specifically, we use a combination of numerical simulations and NMR experiments on adamantane to evaluate and compare the performance of several known sequences that aim to suppress …

Developing Real-Time, Online Beam Control Of Uhdr Irradiators To Facilitate Flash Translational Investigations, Austin M. Sloop

Dartmouth College Ph.D Dissertations

The field of radiation oncology seeks novel techniques to increase the therapeutic ratio to treat malignancies while minimizing damage and toxicities in healthy tissues. While it was observed that delivering therapeutic doses at high dose rate could elicit lower biological effects over a half-century ago, the field of ultra-high dose rate (UHDR) radiation therapy (colloquially known as FLASH RT) has seen a resurgence in recent years due to an alignment of accelerator capability, dosimetric advances, and improved biotechnological techniques. This has opened the door to studying potential underlying mechanisms such that we may leverage the effects of FLASH tissue sparing …

Eulerian Smoke Simulation With Multiple Fields, Diyang Zhang

Dartmouth College Master’s Theses

Fluid simulation is a cornerstone of computer graphics, enabling the realistic depiction of dynamic phenomena such as smoke, fire, and other gaseous behaviours. This thesis focuses on advancing Eulerian smoke simulation techniques, with a particular emphasis on grid-based simulations that capture intricate vortical structures and fine visual details.

We propose several detail-preserving frameworks that incorporate various scalar and vector fields within the simulation pipeline, including velocity, impulse, and Lamb vectors, along with their decompositions and transformed representations. By mathematically analyzing the properties of impulse, we derive its scalar fields decomposition (ImpSFD), which introduces an alternative numerical interpretation, and Vortex-Particles in …

Design, Characterization, And Simulation Of A 2d Dual-Rail Quantum Processor, Diego Barrutia

Dartmouth College Master’s Theses

Bosonic systems, such as three-dimensional (3D) λ/4 coaxial cavities and two-dimensional (2D) λ/2 coplanar waveguide (CPW) resonators, are quantum harmonic oscillators that encode information in phase space, offering a hardware-efficient route toward quantum error correction and simulation in superconducting circuits. In this thesis, we present the design, characterization, and simulation of a dual-rail processor constructed with a 2D λ/2 coplanar waveguide resonators, demonstrating a percent error between experimental and analytical results within a range of 3.31% - 13.16%. The analytical results exhibit high precision but lower accuracy relative to experimental measurements. By integrating both closed-source and open-source software tools, we …

Thermal Phase Fluctuations In Narrow Superfluid Rings, Parth Sabharwal

Dartmouth College Ph.D Dissertations

Remarkable advances have been made in the past decade in the ability to control superfluids in circuit-like configurations. Especially notable are the improvements in the initialization, stabilization and measurement of the circulation of superfluids in geometries with periodic boundary conditions, such as rings. This has significant implications for applications as rotation sensors, magnetometers, and in the emerging field of atomtronics. As the push towards studying supercurrents in lower dimensions and higher aspect ratios continues, in order to realize idealized experimental conditions and explore unusual quantum phases, phase fluctuations become increasingly pronounced, with the potential to destroy long-range order. In this …

Unveiling The Magnetic And Structural Properties Of Hydrohematite : A Potential Water-Bearing Mineral On The Surface Of Mars, Abdullah Al Maruf

Dartmouth College Master’s Theses

Hematite (α-Fe₂O₃) is one of the most prevalent iron oxides in sedimentary rocks and on the surface of Mars. Recent studies suggest that natural "hydrohematite" exists, wherein hematite accommodates cations through compensation at the Fe³⁺–site, forming –OH bonds (i.e., structural water), with important implications for water in arid planetary environments. We present a detailed magnetic characterization to elucidate the magnetic response of H–doping on these samples, corroborating the results with first-principles calculations. First-order reversal curves show a sharp diagonal wing due to triaxial basal plane anisotropy. Low-temperature cooling experiments show the complete suppression of …

Simulating Cross-Scale Solid-Fluid Interaction Phenomena, Jinyuan Liu

Dartmouth College Ph.D Dissertations

Solid-fluid interactions are ubiquitous in nature, and accurate simulation methods are essential for realistic animation, industrial design, and engineering analysis. Com- pared to large-scale coupling phenomena, simulating fine-scale interactions poses extra challenges due to factors such as surface tension, material wettability, and geometric complexity. In this thesis, we pursue novel methodologies to accurately model in- terfacial dynamics between surface-tension fluids and codimensional solids, involving capillary interactions, controllable wettability, and robust contact behaviors. Our ini- tial approach involves developing a novel three-way coupling method, which utilizes a thin liquid membrane, modelled as a simplicial mesh, to facilitate accurate momen- tum transfer, …

Probing Central Spin Decoherence Dynamics Of Electronic Point Defects In Diamond And Silicon, Ethan Que Williams

Dartmouth College Ph.D Dissertations

Electron spins of point defects in diamond and silicon can exhibit long coherence times, making them attractive platforms for the physical implementation of qubits for quantum sensing and quantum computing. To realize these technologies, it is essential to understand the mechanisms that limit their coherence. Decoherence of these systems is well described by the central spin model, wherein the central electron spin weakly interacts with numerous electron and nuclear spins in its environment. The dynamics of the resultant dephasing can be probed with pulse electron paramagnetic resonance (pEPR) experiments.

Using a 2.5 GHz pEPR spectrometer built in-house, we performed multi-pulse …