Physics
http://hdl.handle.net/10211.3/5682
2024-03-28T14:36:57ZNumerical Calculations of the Pairing Phenomenon in a Fermi Atomic Gas in the Strongly-Correlated Regime
http://hdl.handle.net/10211.3/211094
Numerical Calculations of the Pairing Phenomenon in a Fermi Atomic Gas in the Strongly-Correlated Regime
Gonzalez, Jimmy
The primary work presented in this thesis focuses on the calculation of
the density-density dynamical correlations in a two dimensional Fermi gas of
ultra-cold atoms in the strongly correlated regime, known in literature as the
BEC-BCS crossover, using the state-of-the-art dynamical BCS theory, and
improving the ability of dynamical BCS to describe the atom pairing behaviour at
the crossover via renormalization. While dynamical BCS theory provides a good
description of the BEC-BCS crossover, renormalizing the interaction strength
between cold atoms and a parameter η, associated with energy resolution and tuned
to the system size, improves the ability of dynamical BCS to describe local motions
and pair structure. The validations of our density-density correlation calculations
for the two dimensional system were done by using recently available exact,
imaginary time Quantum Monte Carlo results for the two dimensional atomic gas,
provided by Auxiliary Field Monte Carlo methodology (AFQMC). We deduce the
feasibility of dynamical BCS theory as a description of Fermi atomic gases at the
crossover after a renormalization procedure is applied. Our results suggest that
dynamical BCS is able to provide quantitatively accurate results, and allows for the
possibility of studying very large systems, something that QMC struggles with due
to the complexity of algorithms involved.
2019-05-01T00:00:00ZSynthesis and Characterization of Rare-Earth Nanoparticles using an Organometallic Reduction Solution and 1-Octylamine Ligand
http://hdl.handle.net/10211.3/211027
Synthesis and Characterization of Rare-Earth Nanoparticles using an Organometallic Reduction Solution and 1-Octylamine Ligand
Talbot, Patrick R. M.
We are developing a method for the production of rare-earth (RE)
nanoparticles, (NPs). A reliable production method will ease future investigation
of emergent electrical and magnetic properties that may arise when applying
quantum confinement to rare-earth metals. New properties may allow for
advances in magnetic imaging, magnetic information storage, and magnetic
refrigeration.
The primary obstacle to producing and stabilizing RE NPs is the reactive
nature of RE elements, which have an oxidation potential around -2 V or greater,
requiring a strong reducing agent to form from an oxidized state, and oxidizing
under ambient conditions.
For forming the NPs we are testing the use of electride, alkalide, and
organometallic solutions, since they are some of the strongest reducing agents
available. As for the stabilization and protection of the NPs, we are interested in
using ligands since they bond to the surface of the NP, possibly providing a more
effective barrier compared to the use of micelles.
For analysis we will use; x-ray diffraction (XRD), scanning electron
microscopy (SEM), and energy dispersive x-rays (EDX) techniques.
2019-05-01T00:00:00ZEfficacy of a Physics Laboratory Model Centered on Scientific Reasoning
http://hdl.handle.net/10211.3/211023
Efficacy of a Physics Laboratory Model Centered on Scientific Reasoning
Squire, Stephan Lucas
This research is a study on the effects of a newly developed laboratory model
on student performance in introductory calculus-based physics at California State
University, Fresno. The study investigated how scientific reasoning, statistical
analysis, and conceptual knowledge were impacted during the Fall 2018 semester.
Students were grouped into treatment groups (students enrolled in the lab sections
with the new lab model) or control groups (students enrolled in the lab sections
with the traditional lab model). Students’ scientific reasoning and statistical
analysis skills were assessed by comparing pre- and post-project scores on a
multiple-choice survey of scientific reasoning skills called iSTAR. Students’
conceptual knowledge was assessed by comparing the performance on the Force
Concept Inventory (FCI) and a common final exam. Using the method of
hypothesis testing of a two-sample t-test, this study found that there was
insufficient statistical evidence to establish a correlation between the new laboratory
model and students’ scientific reasoning, statistical analysis, and conceptual
knowledge development; however, there is enough statistical evidence to encourage
future studies to be conducted by increasing the sample size as well as by
diversifying the number of lecturers involved in the study.
2019-05-01T00:00:00ZModified Commutation Relationships from the Berry-Keating Program
http://hdl.handle.net/10211.3/210985
Modified Commutation Relationships from the Berry-Keating Program
Aiken, Erick Robert
This work is a study of the introduction of gravity to quantum theory.
The presence of the Riemann zeta function in string theoretic arguments suggests
a connection between the zeta function and quantum theory. Current approaches
to quantum gravity suggest there should be a modification of the standard quantum mechanical commutator, [x,p] = i~. Typical modifications are
phenomenological and designed to result in a minimal length scale. As a
motivating principle for the modification of the position and momentum
commutator, we assume the validity of a version of the Bender-Brody-Mu¨ller
variant of the Berry-Keating approach to the Riemann hypothesis. Through our
research we arrive at a family of modified position and momentum operators, and
their associated modified commutator, which leads to a minimal length scale.
Additionally, this larger family generalizes the Bender-Brody-Mu¨ller approach to
the Riemann hypothesis.
2019-05-01T00:00:00Z