Physics Commons^™

A Monte-Carlo Simulation Of Gamma Rays In A Sodium Iodide Detector, Ben Kessler

Physics

Gamma rays principally interact with matter through Compton scattering, photoelectric effect, pair production, and triplet production. The focus of this simulation is to study the theoretical energy spectrum created by gamma rays from a Cesium-137 source, which produces gamma photons with an energy of 0.662 MeV. At this energy level, most interactions are results of Compton scatters and the photoelectric effect. Therefore, this simulation only models those two effects on gamma rays. Using Monte Carlo methods and the Metropolis algorithm to sample the probability distributions of the two effects allowed for the simulation of gamma rays in a Sodium Iodide …

Developing A Data Acquisition System For Use In Cold Neutral Atom Traps, Jonathan E. Fuzaro Alencar

Physics

The rising interest in quantum computing has led to new quantum systems being developed and researched. Among these are trapped neutral atoms which have several desirable features and may be configured and operated on using lasers in an optical lattice. This work describes the development of a new data acquisition system for use in tuning lasers near the precise hyperfine transition frequencies of Rb 87 atoms, a crucial step in the functionality of a neutral atom trap. This improves on previous implementations that were deprecated and limited in laser frequency sweep range. Integration into the experiment was accomplished using an …

Automation Of The Transition Identification Procedure For Trapping Rubidium Atoms In A Magneto-Optical Trap, Michael P. Fletcher

Physics

The words “quantum computer” often conjure images of science fiction and unrealistic technology from an impossible future. Some may even believe that they aren’t real or are only theoretical. The truth is that quantum computers are real, tangible systems with real life uses and rooted in credible scientific research. Today, many groups of scientists collaborate on research into better ways of implementing and improving quantum computing techniques. This paper will be addressing the systems required and phenomena used to achieve neutral atom trapping for quantum computation. This thesis will outline the physical phenomena involved with the frequency tuning process for …

Design And Characterization Of Standard Cell Library Using Finfets, Phanindra Datta Sadhu

Master's Theses

The processors and digital circuits designed today contain billions of transistors on a small piece of silicon. As devices are becoming smaller, slimmer, faster, and more efficient, the transistors also have to keep up with the demands and needs of the daily user. Unfortunately, the CMOS technology has reached its limit and cannot be used to scale down due to the transistor's breakdown caused by short channel effects. An alternative solution to this is the FinFET transistor technology, where the gate of the transistor is a three dimensional fin that surrounds the transistor and prevents the breakdown caused by scaling …

Quantum Random Walk Search And Grover's Algorithm - An Introduction And Neutral-Atom Approach, Anna Maria Houk

Physics

In the sub-field of quantum algorithms, physicists and computer scientist take classical computing algorithms and principles and see if there is a more efficient or faster approach implementable on a quantum computer, i.e. a ”quantum advantage”. We take random walks, a widely applicable group of classical algorithms, and move them into the quantum computing paradigm. Additionally, an introduction to a popular quantum search algorithm called Grover’s search is included to guide the reader to the development of a quantum search algorithm using quantum random walks. To close the gap between algorithm and hardware, we will look at using neutral-atom (also …

An Overview Of Lasers And Their Applications, Luis Cristian Giovanni Guerrero

Physics

This paper is an overview of lasers and their applications. The fundamentals of laser operation are covered as well as the various applications of advanced laser systems. The primary focus is to highlight some of the technological advancements made possible by lasers in the last half-century.

Investigating The Talbot Effect In Arrays Of Optical Dipole Traps For Neutral Atom Quantum Computing, Sergio Aguayo

Physics

Quantum computers are devices that are able to perform calculations not achievable for classical computers. Although there are many methods for creating a quantum computer, using neutral atoms offers the advantage of being stable when compared to other methods. The purpose of this investigation is to explore possible optical dipole trap configurations that would be useful for implementing a quantum computer with neutral atoms. Specifically, we computationally investigate arrays of pinholes, the diffraction pattern generated by them, and the onset of the Talbot effect in these traps. We manipulate the radius of the pinholes, the number of pinholes in the …

Optimization Of An Injection Locked Laser System For Cold Neutral Atom Traps, Elliot M. Lehman

Physics

Many types of quantum systems are being explored for use in quantum computers. One type of quantum system that shows promise for quantum computing is trapped neutral atoms. They have long coherence times, since they have multiple stable ground states and have minimal coupling with other atoms and their environment, and they can be trapped in arrays, making them individu- ally addressable. Once trapped, they can be initialized and operated on using laser pulses. This experiment utilizes a pinhole diffraction pattern, which can trap atoms in both bright and dark areas. To maximize trap strength, an injection-locked laser amplification system …

Assembling And Characterizing The Efficiency Of An Injection Locked Laser System For Cold Neutral Atom Optical Traps, Alexandra Papa Crawford

Physics

Creating a quantum computer requires a system of particles that can be well-controlled to achieve quantum operations. We need a large array of these particles – called qubits – with long coherence times, which can be initialized, operated on by single and two qubit gates, and read out. For neutral atoms, the qubit states are stable ground states that interact minimally with the environment, leading to long coherence times. Experimentally, the qubits are manipulated using carefully timed laser beam pulses with controlled frequency and intensity, but the outstanding issue for optically trapping cold atoms is finding a light pattern that …

X-Ray Spectroscopy Of Nio And Nanodiamond At Ssrl, Jackson Earl

STAR Program Research Presentations

The first aspect of this research project focuses on investigating the surface chemistry of high pressure high temperature (HPHT) nanodiamond by using X-ray spectroscopy techniques at the Stanford Synchrotron Radiation Lightsource (SSRL). HPHT nanodiamond is being examined as a biosensing tool for electric field detection based on the fluorescent nitrogen vacancy center hosted within diamond. With use of the transition edge spectrometer (TES), a state-of-the-art X-ray fluorescence detector, we are able to probe the surface and bulk properties of diamond. Preliminary work using density functional theory (DFT) has been done, offering insight into ground state energies and electronic structure. DFT …

Improvements For The T0c+ Geometry Of The Fast Interaction Trigger (Fit) Upgrade To Alice At The Cern Lhc, Noah Miller

Physics

The purpose of the ALICE experiment at CERN is to investigate the properties of the strongly interacting quark-gluon plasma formed in the high-energy collisions of lead nuclei in the CERN Large Hadron Collider. ALICE has been collecting data since 2009. The upcoming upgrade of the CERN LHC injectors during 2019-20 will boost the luminosity and the collision rate beyond the design parameters for several of the key ALICE detectors including the forward trigger detectors. The new Fast Interaction Trigger (FIT) will enable ALICE to discriminate beam-beam interactions with a 99% efficiency for the collisions generated by the LHC at a …

My Contributions To The Cryogenic Underground Observatory For Rare Events Experiment And The Utilization Of Geant4 In Their Analysis, Kevin Armenta

Physics

First, a brief introduction and background of the basics of particle physics and the Standard Model is discussed in order to give context to nature of the neutrinoless double beta decay ($2\nu\beta\beta$) and why it is so interesting to particle physicists. Next, the Cryogenic Underground Observatory for Rare Events (CUORE) experiment is discussed in detail, explaining the rational behind the experimental setup and detection process. Finally, I conclude by discussing Geant4, an important software toolkit used in particle physics, and how it is utilized in the CUORE experiment.

Developing An Imaging System To Monitor Atom Traps For Neutral Atom Quantum Computing, Jenna Valdez

Physics

Quantum computing exploits the laws of quantum mechanics to exponentially increase computing rate for certain processes. A realized quantum computer could break encryptions and simulate large quantum systems previously unbreakable and unattainable with classical computers. Neutral atom quantum computing is a viable candidate for building these devices that satisfies four of the five criteria for a successful quantum computer. We are exploring a novel method in creating neutral atom qubits that involves a magneto-optical trap and a dipole trap created in the diffraction pattern behind an array of pinholes. The magneto-optical trap works to cool the atoms and centralize them …

Spontaneous Parametric Down Conversion Of Photons Through Β-Barium Borate, Luke Horowitz

Physics

An apparatus for detecting pairs of entangled 405nm photons that have undergone Spontaneous Parametric Down Conversion through β-Barium Borate is described. By using avalanche photo-diodes to detect the low-intensity converted beam and a coincidence module to register coincident photons, it is possible to create an apparatus than can be used to perform quantum information experiments under a budget appropriate for an undergraduate physics lab.

Calculating The Energy Barriers Required To Join Metal-Organic Framework Synthesis Intermediates With Non-Equilibrium Molecular Simulation, Marcus A. Tubbs, David Cantu, Roger Rousseau, Vassiliki-Alexandra Glezakou

STAR Program Research Presentations

Metal organic frameworks (MOFs) are synthetic materials made of a cage-like lattice of metal nodes connected by organic linkers. The pores between the nodes define the characteristics of the material. A MOF, MIL-101, has shown great capacity in the adsorption of carbon dioxide and methane, as well as in hydrogenation catalysis with palladium. While there has been success in synthesizing MIL-101 and other MOFs, the mechanistic details behind their assembly remain unknown. Understanding the synthesis mechanism is necessary to understand the kinetics involved and be able to produce this useful material on an industrial scale. Using MIL-101 as a prototypical …

Fission Fragment Tracking And Identification In The Neutron-Induced Fission Fragment Tracking Experiment’S Time Projection Chamber, Eric Song

Physics

The Neutron-Induced Fission Fragment Tracking Experiment (NIFFTE) built a novel Time Projection Chamber (TPC), the FissionTPC, for measuring neutron-induced fission cross-sections to unprecedented precision. We investigated data from a 2014 run (400010151) at the Los Alamos Neutron Science Center (LANSCE) with a double-sided U235/Pu239 target. Our particle identification studies will aid in the development of improved tracking algorithms.

Characterizing Double And Triple Laser Beam Interference Patterns In The Context Of Trapping Atoms For Quantum Computing, Ian E. Powell

Physics

We propose two optical neutral atom traps for quantum computing involving the intersection of two or three laser beams. We simulate both the intensity and the potential energy of the interference pattern. From these simulations we create animations of how the potential energy and intensity change with varying angles of separation between the laser beams in the system. We parameterize lines through our interference pattern and fit simple harmonic oscillator potential energies to the potential energy wells calculated to characterize our interference pattern’s atom trapping capabilities. Finally, we investigate a possible quantum entanglement routine by observing how the geometry of …

High Speed Control Of Atom Transfer Sequence From Magneto-Optical To Dipole Trap For Quantum Computing, Jason Garvey Schray

Physics

Two circuits were designed, built, and tested for the purpose of aiding in the transfer of 87Rb atoms from a MOT to dipole traps and for characterizing the final dipole traps. The first circuit was a current switch designed to quickly turn the magnetic fields of the MOT off. The magnetic coil switch was able to reduce the magnetic field intensity to 5 % of its initial value after 81 μs. The second circuit was an analog signal switch designed to turn the modulation signal of an AOM off. The analog switch was able to reduce the modulation signal intensity …

Environmental Testing Of Lasers For Jpl's Cold Atom Laboratory, Carey L. Baxter

STAR Program Research Presentations

NASA’s Cold Atom Lab (CAL) is a multi-user facility designed to study ultra-cold quantum gases in the microgravity environment of the International Space Station (ISS). One of the main goals of CAL is to explore the unknown territory of extremely low temperatures—possibly as low as the picokelvin range!—where new and fascinating quantum phenomena can be observed. At such temperatures matter stops behaving as particles and instead becomes macroscopic matter waves. CAL will be remotely controlled to perform a multitude of experiments and is scheduled to launch in 2016. In order to anticipate problems that might occur during and post-launch, including …

A Prototype Microwave Cavity Control Circuit For Use In Next Generation Free Electron Laser, Josh Thompson, Peter Neal Barrina, Jiayi Jiang, Joe Frisch, Steve Smith, Daniel Van Winkle

STAR Program Research Presentations

One of the current programs at SLAC National Accelerator Laboratory is the Linac Coherent Light Source, or LCLS. Using the existing hardware of the last third of their linear accelerator (or “linac”), SLAC has created one of the most energetic X-ray free electron lasers (or “FEL”). Since 2009, LCLS has used this FEL to perform a wide range of experiments across all sciences, most notably ultrafast filming at the molecular scale. As requests for beam-time with this laser increases, SLAC is purposing a linac upgrade to better match this demand. This upgrade, named LCLS-II, will replace existing copper radio frequency …

Does A Plastron Improve Heat Transfer?, Madani A. Khan, Jeffrey Alston, Andrew Guenthner

STAR Program Research Presentations

Superamphiphobic surfaces strongly repel both water and oils. In this work, aluminum coupons are processed by sanding with various grit of sand paper to impart microscale roughness. Subsequent submersion of the aluminum substrate in boiling water grows nanoscale grass-like structures. The oxide layer of Al is slightly soluble in water. During a fast diffusion/equilibrium, Al₂O₃ nanograss grows on the surface. A low energy coating is then deposited on the surface. The micro and nanoscale features create re-entrant structures that trap air enabling contact liquid to be in a Cassie-Baxter state. Superamphiphobicity of the samples were confirmed by …

Ultrasonic Bonding For The Cuore Collaboration, John J. Sekerak Ii

Physics

This paper will give the reader a brief introduction to the Standard Model, Neutrinoless Double Beta Decay, and the CUORE experiment under construction at Gran Sasso National Lab in Assergi, Italy. The remainder of the paper will describe the bonding process used to connect the heater pads and NTDs to the copper housings of the tower structure. Extensive details of the troubleshooting and calibration period are presented as a way for the reader to better understand the concepts involved during the bonding stage of the assembly process.

Improving Hybrid Solar Cells: Overcoming Charge Extraction Issues In Bulk Mixtures Of Polythiophenes And Zinc Oxide Nanostructures, Grant T. Olson

Master's Theses

Organic photovoltaics (OPVs) have received a great deal of focus in recent years as a possible alternative to expensive silicon based solar technology. Current challenges for organic photovoltaics are centered around improving their lifetimes and increasing their power conversion efficiencies. One approach to improving the lifetime of such devices has been the inclusion of inorganic metal oxide layers, but interaction between the metal oxides and common conjugated polymers is not favorable. Here we present two methods by which the interactions between polythiophenes and nanostructured ZnO can be made to be more favorable. Using the first method, direct side on attachment …

Developing A Diffraction Pattern Projection System For Neutral Atom Quantum Computation, Sanjay Khatri

Physics

No abstract provided.

Characterization Of Polarized Synchrotron Light, Britny N. Delp, Jeff Corbett

STAR Program Research Presentations

The Stanford Synchrotron Radiation Light accelerates electrons around a 234-meter circumference ring at relativistic speeds. The x-ray radiation produced by this process is used in many fields of science ranging from materials science to medicine.

This project seeks to measure the polarization of the 532 nanometer wavelength component in the visible light beam emitted from the SPEAR-3 synchrotron as a function of vertical position. The beam was focused through a lens, then passed through a 532 nm band pass filter and a polarizer mounted on a rotating stand. The beam power was measured as a function of vertical position and …

Breaking Peroxy Bonds In H20 Ice Doped With H202 To Create Positive Hole Charge Carriers., Corey C. Stockburger

STAR Program Research Presentations

Using stress-activated electric conductivity in water ice doped with hydrogen peroxide as a model for stress-activated electric conductivity of igneous and high-grade metamorphic rocks due to the presence of peroxy defects, which when broken, createpositive-hole charge carriers. Blocks of pure H2O ice and H2O2–doped H2O ices, frozen at –20°C, will be stressed with piezo electric transducers(pzt) at one end to generate stress-activated electric currents flowing down the stress gradient. Pure H2O ice should produce no current or a small insignificant amount during rapid deformation or fracture. Stressing H2O2-doped H2O ices, however, should lead to 100-1000 times higher currents. These stress-activated …

The Standard New Astronomy Cryostat For Sofia: A Design For Cryogen-Free Infrared Astronomy, Carey F. Scott, Jeffrey Van Cleve, Eric Burgh, Earl T. Daley, Ali Kashani, Zaheer Ali

STAR Program Research Presentations

Astronomy at infrared wavelengths requires optical instruments that operate at low temperatures, which is typically done using liquid cryogens such as nitrogen and helium. These cryogens are costly and limit the operational time of the science instrument. The Standard New Astronomy Cryostat for SOFIA (SNACS) will provide a design for a helium cryocooler-cooled cryostat that meets the stringent airworthiness requirements of the Stratospheric Observatory for Infrared Astronomy (SOFIA) and can be used by future instrument builders to reduce the cost and risk of their instrument design and development. The SNACS dewar will provide approximately 3.4 x 10^-1 cubic meters …

Tilt Angle And Birefringence Of Smectic Liquid Crystal Materials, Taylor Van Winkle

Physics

No abstract provided.

Experimenting With Polymer Blend Solar Cells And Active Layer Thickness, Ryan Blumenthal

Physics

Bulk heterojunction organic photovoltaics utilize the electrical characteristics of semi-conductive polymers. These solution processable materials are beneficial because of their low material cost, light weight, and simple fabrication requirements. Our devices employ multiple photoactive polymers, P3HT and PCPDTBT, to absorb photons over a wide spectral range. We optimized various device characteristics including thickness and thermal anneal usage to reach a power conversion efficiency of 3.0% in AM1.5 sunlight. Device performance degrades over time due to atmospheric water and oxygen, prompting us to investigate device packaging to extend cell lifetime for additional testing.

Nested Gaussian Laser Beams - A Blue-Detuned One-Dimensional Lattice Of Optical Dipole Traps For Quantum Computing, Travis Daniel Frazer

Physics

No abstract provided.