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PML 2020 SURF Projects

Contact Name Phone Title Description
Yaw Obeng 301-975-8093 Study of reversible photostructural changes in a chalcogenide glass Chalcogenide glasses are metamaterials and can serve as models for emerging 2-D Wan der Walls materials (i.e., 2-D metal dichalcogenide films (such as MoS2 etc.)). For emerging nanoelectronic interconnects use, we need to characterize the intrinsic properties of such materials.  In this summer project we will attempt to characterize the kinetics of, and elucidate the underlying atomic scale mechanisms, reversible photo-structural changes in a chalcogenide glass. Our objectives include understanding the structural change induced by continuous wave-light of low intensity UV-light (“black light” from Cole-Palmer). The process can be partially reversed by changing the wavelength of the inducing light or completely reversed by annealing just under the glass-transition temperature.  The material is always in the amorphous state. We will primarily use BDS to extract the electrical characteristics of the Ge-glass materials, monitor the UV-induced changes in Ge-glass, and attempt to understand the significant site-to site variability in the sample.
Zachary Levine 301-975-5453 Theory of Solid-State Quantum Memories Memory a critical requirement for workable quantum computing and quantum communication. In support of ongoing experiments in solid-state quantum memory at the JQI, the SURF fellow will perform relevant simulations. In particular, the experiment involves the use of praseodymium-doped yttrium orthosilicate. Electromagnetically induced transparency is achieved using a laser which is stabilized to 500 Hz (i.e., with 12 digits of precision). At this level, it is possible to have coherent control of certain atomic levels in the 4f shell of praseodymium, which, in turn, involves solving the optical Bloch equations. A similar project was proposed last year.  At this writing, there are two descriptions of the preparation of the memory, using the rate equation or the density matrix.  Interest is now shifting to 3D effects, e.g., how does the gradual brightening in the crystal affect the results?  What is the outgoing radiation pattern? A key question is whether the Dicke state description of a pulse absorbed in a delocalized way across the crystal has observable effects which differ from a model of a quantum description of the impurity atoms being connected by classical electrodynamics, and in particular, a dielectric function. 
Denis Bergeron 301-975-2282 Fluorometric assays of lithium ions One very successful approach to building large-scale neutrino detectors relies on thousands of liters of organic liquid scintillator. Such detectors are most sensitive when loaded with high fractions of 6Li-enriched aqueous LiCl. Since very pure 6LiCl is expensive and requires a concerted effort to produce, an efficient approach to recovering the material at the end of an experiment is desired. We are developing strategies at NIST, and this project will be part of that effort. The fellow will focus on refining a fluorometric technique based on a metallocrown complex. The fellow will carry out wet-chemistry preparation of the Li-selective complex and establish absolute calibrations.
Stephen Eckel 301-975-8571 Magnetic trap lifetime measurements with Li and Rb In our lab, we are developing an experiment that will serve as a new, cold-atom based vacuum standard.  Students working on this project will help measure the fundamental cross-sections for collisions between laser-cooled sensor atoms and room-temperature (thermal) background gas molecules.  The student will primarily work with others in the lab to optimize aspects of the apparatus: loading a magnetic trap with laser-cooled atoms from the existing magneto-optical trap, measuring the trapped gas temperature, measuring the spin purity of the trapped atoms, and finally measuring the lifetime of atoms in the trap and comparing them to lifetimes measured in the magneto-optical trap.  Depending on progress in the laboratory before the start of the SURF program, the student may also assist with the development of the flowmeter system that injects known quantities of gas into the apparatus.  This course of work would primarily focus on software development to control the flowmeter.  Past students on the project have gained a host of experience with lasers, electronics, computer control software, vacuum systems, and gas handling.
Marcelo Davanco 301-975-3089 Design of nanophotonic devices for single quantum emitters This project involves the design of nanophotonic structures for creating efficient sources of non-classical light based on single quantum light emitters, such quantum dots. The investigation will be based on numerical electromagnetics simulations and optimization methods, and will involve programming tasks for optimization procedures, simulation data analysis and nanophotonic device layout.
Ryan Fitzgerald 301-975-5597 Modeling radiation detectors to assay radioactive material  This project involves creating a computer model of radiation detectors used at NIST for quantifying how much radioactive material is in a given sample. Samples could involve soil or food that has been contaminated, or nuclear medicine products. Once completed and validated, the model will be used to predict detector response from various radioactive sources. The model will be created by modifying an existing model of a different detector system using Geant4 Monte Carlo software. The Monte Carlo method is appropriate for simulating random processes, such as radioactive decay. Creating the model will involve modifying C++ source code to input the geometry of the sources and radiation detectors and testing to find the most important parameters to understand. The completed model will not only show the 3D geometry, but also track simulation radiation as it moves through the system and calculate the overall detection efficiency.
Richard Steiner 301-975-4226 Testing the accuracy of digital electric utility meters (Smart Meters) under distorted waveform power usage for application to the USA Smart Grid This research investigates the accuracy of digital electric-energy utility meters under unusual power loads. Modern electronics use digital electronics that causes current spikes. Smart Meters are designed to measure electric energy usage more accurately than the older mechanical meters, but there are limits to the accuracy of the meters under extreme current spikes. This project involves running a program to measure the Smart Meters, analyzing the data for accuracy and uncertainty, and performing signal analysis to characterize the structure of the current spikes in harmonic frequency or time-domain space. Studying power loads combining DC power (solar energy) with digital-induced power spikes is also of interest. 
Ian B. Spielman 301-246-2482 Rapid transport of ultracold atoms with Bessel beams of light Ultracold atoms are foundational for modern quantum mechanics experiments, with applications ranging from atomic clocks and magnetometers as well as enabling basic physics such as quantum simulation.  All of these experiments operate by first capturing an ensemble of cold atoms followed by manipulating and measuring them in some way.  This process is destructive in the sense that a new ensemble of atoms is needed for each measurement.  Reducing this cycle time is a key technical goal of next generation experiments. In our experiments, we often transport cold atoms from a capture zone to an experimental zone, and this SURF project will explore using an optical lattice of Bessel laser beams for this transport.  Bessel beams are non-diffracting, i.e., shape preserving, beams of light.  This makes them ideal for atomic wave-guides because their optical properties can be made to be position independent. In this project the SURF student will first create Bessel beams on the bench and setup bench test of the transport geometry prior to installing the setup on laser cooled 39K.
Bob McMichael 301-975-5121 Bayesian statistics for smarter measurements Develop, simulate and test measurement strategies using Bayesian methods.  Typically, we take measurements and analyze later.   In this project, we are using Bayesian inference to analyze data in real time, using the results to make informed choices about the next round of measurement.  See https://pages.nist.gov/optbayesexpt for more info.  The successful SURFer will gain experience with Bayesian statistics, instrumentation control, Python programming and github.  Fluency in Python is required.
Joseph Robertson 301-975-2506 Structural analysis of viral single stranded DNA for optimization of DNA nanotechnology Structural DNA nanotechnology, known as DNA origami, is a self-assembly driven nanoassembly method for creating shaped molecular scaffolds for a wide variety of applications.  The challenges in characterizing the assembly process limits the efficacity of incorporating these structures into scalable applications.  The student will design and develop measurements using light scattering, flow-injection analysis and coarse-grained molecular dynamics to characterize the kinetics of nanostructure assembly with the goal of improving the assembly of nanostructures for use in a wide range of technologies.
Curt A. Richter 301-975-2082 Autonomous search and identification of novel two-dimensional materials  Because of an explosion of research into the properties novel two-dimensional (2D) materials and their applications, there is a strong demand for these materials -- especially from the exfoliated sources. We are automating the optical search and characterization process for atomically thin layers of these 2D materials. This fast search approach will speed our ability to form heterogeneous stacks of 2D materials and explore their emergent quantum properties. The SURF student will spend the first part of the project performing mechanical exfoliation and optical inspection of 2D layered materials in order to build a library of materials. They will then use that library of materials to "train" open-source python code with the goal of automating the search and characterization process for novel 2D layered materials. It is anticipated that the student will also carry out some simple electrical characterization of devices containing 2D materials. Reference: https://www.nature.com/articles/s41467-018-03723-w
Michael G. Huber 301-975-5641 From Source to Sample: Neutron Transport for Neutron Interferometry Neutron scattering techniques such as tomography, triple-axis spectrometry, small angle scattering and interferometry, are used in material science, analytical chemistry, nuclear science and fundamental physics. Incoherent neutron beams, produced by nuclear processes, contain wide distributions of energies and momentums.  In this way neutron sources are more analogous to light bulbs than the more familiar (coherent) laser sources.  In spite of the challenges associated with the source, world-wide neutron facilities are oversubscribed.   The large phase-space provided by the source in conjunction with the unique properties of neutrons creates difficulties in obtaining optimal setups.  The student will learn the basics of  ray-tracing simulations, neutron optics, and neutron optical components in order to maximize intensity at the interferometry facilities at the NCNR. 
Victoria DiStefano 301-975-5143 Mineral Mapping of Synthetic Rocks using Neutron Imaging The goal of this project is to use neutron imaging to identify and map common minerals found in rocks. Neutron imaging is an ideal tool to non-destructively map 3D structure of a polycrystalline material. In this project, the researcher will create synthetic rocks composed of large mineral crystals of known size and orientation. They will then use neutron imaging to try and accurately create a 3D model of the rock assemblage.  As a part of this project, the researcher will:
1. Design an experiment to analyze synthetic rock samples
2. Create synthetic rocks
3. Conduct experiments on neutron imaging beamline
4. Analyze results of the experiments
5. Present results clearly and concisely
The results from this experiment will be used to validate this technique for real space mineral mapping of natural rocks of unknown compositions.
Kartik A. Srinivasan 301-975-5938 Broadband dispersion measurements for nanophotonic chips Dispersion – the variation in the speed of light as a function of wavelength – is a critical ingredient in nonlinear optical phenomena, and can be manipulated through geometry in nanophotonic chips.  In this project, the student will build a photonic test setup for characterizing dispersion of nanophotonic devices.  The setup will be applied to nonlinear nanophotonics technologies made in our lab, including microresonator frequency combs and frequency conversion devices.
Garnett W. Bryant 301-975-2595 Quantum simulations with atom and quantum dot arrays in solid-state systems: A quantum lab on a chip Quantum dot arrays and arrays of dopant atoms in Si provide exciting new opportunities to perform quantum simulations. Solid-state systems provide the opportunity to do simulations dot by dot or atom by atom with precise placement and geometry, local gates, applied fields and strong hopping that allow the low T limit to be reached. We are performing theoretical simulations done with small arrays of quantum dots or dopant atoms used to implement extended range Fermi-Hubbard models. For example, we consider an array of QDs with small QDs (qubits) attached to opposite ends of the array. This can model, for example, the dynamics of long range exchange or coherent quantum state transfer between two qubits mediated by an intermediate, many-body, large QD. We will use the simulations to determine how excitations, quantum resources (entanglement) and quantum states can be transferred between qubits through the mediator QD. Results will be used to better understand how to use such arrays as a quantum lab on a chip.
Amit Agrawal 301-975-4633 Reconfigurable phase change metasurfaces based on germanium-antimony-tellurium (GeSbTe) thin films Metasurfaces, flat optical elements of wavelength scale thickness, are able to change the amplitude, phase and polarization of incident light akin to bulk optics. Development of fabrication and design capabilities in this area have led to the ability to change the spatio-temporal properties of light arbitrarily in a compact integration friendly footprint. However, almost all embodiments of metasurfaces till date are static meaning that once fabricated their optical functionality cannot be changed. In this project, the fellow will develop an active metasurface platform based on germanium-antimony-tellurium (GST) phase-change material wherein the optical functionality can be changed with temperature (through thermal, electrical or optical means). The fellow will use the nanofabrication facility at NIST to deposit and characterize the optical properties of GST thin films, and develop etching recipe for fabrication of metasurface building blocks. Active metasurface and plasmonic devices based on phase change materials is expected to result in a low-energy reconfigurable switching platform for application in nanophotonics and optical information processing.
Bryan Barnes 301-975-3947 Quantitative Machine Learning: Deep-subwavelength dimensions using optical microscopy and statistics Compared to the Apollo 11’s onboard guidance computer, a modern cellphone is about 1,400 times faster and has 4,000,000 times more memory [1], with these improvements due to miniaturization and high-volume manufacturing (HVM).  Today’s phones enable not just access to artificial intelligence hosted on cloud servers but also empower, for example, local convolutional neural networks (CNNs) for image identification.  Measurement of these powerful chips as they are fabricated in HVM is essential, and no measurement method is as ubiquitous in HVM as optics given its low cost, non-destructiveness, and inherent speed; optics ensures that nanoscale features in the chip are properly aligned, free of defects, and correctly sized even as widths are well-below conventional resolution limits.  We are researching how optics can be enhanced with CNN for better detecting “killer” defects, a binary problem (i.e. defect/no-defect) [2].  We are also tackling the challenge of applying ML to optical results for quantitative dimensional measurements.  Here, we seek not just a numeric value from ML but also the uncertainty in that result.  This project aims to demystify the “black box” for application in quantitative measurements, and we envision publication of not just peer-reviewed articles but also of data and code as well to serve U.S. industry.  [1] Silverman, Houston Chronicle (11 April 2019); [2] Henn et al., OSA Continuum 2, 2683 (2019).
Gillian Nave 301-975-4311 Measurements of branching fractions and oscillator strengths in singly-ionized chromium This project is to measure oscillator strengths of spectral lines of singly-ionized chromium (Cr II) that are needed for the interpretation of astrophysical spectra such as those from instruments on the Hubble Space Telescope. The student will analyze existing spectra of chromium hollow cathode lamps and radiometric standard lamps measured using Fourier transform spectroscopy. They will intensity calibrate the hollow cathode spectra with the standard lamp spectra and use the results to measure relative intensities of spectral lines of singly-ionized chromium. If necessary, additional spectra will be measured using a vacuum ultraviolet Fourier transform spectrometer. They will use relative intensities to measure branching fractions and oscillator strengths.
Darine El Haddad / Stephan Schlamminger 301-975-3609 A GUI for mass realization in the revised quantum SI For more than a century, the kilogram (kg) — the fundamental unit of mass in the International System of Units (SI) — has been defined as exactly equal to the mass of a small polished cylinder, cast in 1879 of platinum and iridium. In May 2019, the SI was revised and the unit of mass is now realized from three fundamental reference constants: the Planck constant h, the speed of light c, and the unperturbed ground state hyperfine transition frequency of the cesium 133 atom. Experimentally the realization is carried out with a Kibble balance. At NIST, the is the fourth generation Kibble balance NIST-4 provides the nation's mass standard. A data-analysis software and graphical user interface are required to analyze multiple channels and visualize the useful data in a user-friendly interface. 
Created January 15, 2020