Bulletin of the American Physical Society
2020 Annual Meeting of the APS Four Corners Section (Virtual)
Volume 65, Number 16
Friday–Saturday, October 23–24, 2020; Albuquerque, NM (Virtual)
Session B03: Atomic, Molecular, and Optical Physics ILive
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Chair: Samuel Brewer, CSU |
Friday, October 23, 2020 10:30AM - 10:54AM Live |
B03.00001: Quantum-based optical clocks for improved frequency standards and tests of fundamental physics Invited Speaker: Samuel Brewer For decades, atomic clocks based on trapped ions and ensembles of trapped neutral atoms have been at the forefront of precision frequency metrology and tabletop experiments to search for physics beyond the standard model. Simultaneously, advances in trapped-ion quantum information science have led to exquisite control of quantum systems. In recent years, a new field of quantum metrology has emerged, which seeks to harness quantum information science techniques for use in the development of high-performance frequency standards and tests of fundamental physics. In this talk, I will describe an Al$^{+}$ quantum-logic clock, developed at NIST, which is a prime experimental example of this new field of quantum metrology. This system has recently demonstrated a fractional frequency uncertainty of ${\Delta \nu / \nu = 9.4 \times 10^{-19}}$. I will give an overview of the systematic uncertainty evaluation of the Al$^{+}$ clock, recent optical clock comparisons for tests of fundamental physics, and discuss future work on quantum-enabled spectroscopy of highly charged ions. [Preview Abstract] |
Friday, October 23, 2020 10:54AM - 11:06AM Live |
B03.00002: Quantum-based optical clocks for improved frequency standards and tests of fundamental physics Samuel Brewer For decades, atomic clocks based on trapped ions and ensembles of trapped neutral atoms have been at the forefront of precision frequency metrology and tabletop experiments to search for physics beyond the standard model. Simultaneously, advances in trapped-ion quantum information science have led to exquisite control of quantum systems. In recent years, a new field of quantum metrology has emerged, which seeks to harness quantum information science techniques for use in the development of high-performance frequency standards and tests of fundamental physics. In this talk, I will describe an Al$^{+}$ quantum-logic clock, developed at NIST, which is a prime experimental example of this new field of quantum metrology. This system has recently demonstrated a fractional frequency uncertainty of ${\Delta \nu / \nu = 9.4 \times 10^{-19}}$. I will give an overview of the systematic evaluation of the Al$^{+}$ clock, recent optical clock comparisons for tests of fundamental physics, and discuss future work on quantum-enabled spectroscopy of highly charged ions. [Preview Abstract] |
Friday, October 23, 2020 11:06AM - 11:18AM Live |
B03.00003: Modeling Reflectance Spectra of Nanorod Arrays by Arrays of Light Sources Christian Lange, T.-C. Shen It is known that carbon-nanotube forests, nanopillar arrays, and other formations of quasi-periodic nanostructures of various materials (semiconductors, semimetals, and metals) can display a very low light reflectance over a wide range of wavelengths, and that the reflectance eventually starts to rise beyond an onset wavelength. As these materials can be quite reflective in planar form, this phenomenon indicates that morphology rather than material plays a dominant role. However, a quantitative analysis of the reflectance spectra of periodic structures has yet to be established. As a first step, we use an array of light sources to model the reflection from an array of nanorods. We find that similar spectra can be generated. Details of our modeling and comparison with FDTD simulations will be presented. [Preview Abstract] |
Friday, October 23, 2020 11:18AM - 11:30AM Live |
B03.00004: Efficiency Measurement of Two Photon Excitation of Metastable Xenon Daniel Reinfurt, Michael Shaffer, Jacob DeLange, Randy Knize We report on the progress an experiment to characterize the optical generation of metastable xenon with two photon excitation. In order to trap xenon inside a magneto optical trap (MOT), it must first be excited to the metastable state, such that the MOT can utilize the 882 nm cycling transition. We have designed a system to measure the efficiency of two photon excitation in generating metastable Xenon in a collimated atomic beam. Using a retro-reflected 252 nm laser beam, we will optically pump the Xenon, Doppler free, directly from the \textsuperscript{1}S\textsubscript{0} 5p\textsuperscript{6}(0) state to the \textsuperscript{2}P\textsubscript{3/2} 6p[3/2]\textsubscript{2} excited state, removing the need for an intermediate state. This method offers a potential gain of orders of magnitude in efficiency over both the RF discharge and UV lamp excitation methods. This will be a key step in improving the ability of our MOT system to trap samples of xenon, reducing the demands on our differentially pumped vacuum system. PA#: USAFA-DF-2020-332 [Preview Abstract] |
Friday, October 23, 2020 11:30AM - 11:42AM Live |
B03.00005: Studying Materials in Extreme Conditions by Using Single-Shot Ptychography and Talbot Interferometry Methods Daniel Hodge, Arianna Gleason, Richard Sandberg In this talk, we will present how we are developing a method to study materials under extreme conditions with the combination of Talbot interferometry and single-shot ptychography with x-ray free electron lasers. In general, ptychography is a computational method of microscopic imaging. This is an experimental technique that involves recording and processing an extensive amount of diffraction patterns from an object that is displaced to various positions relative to an illuminating beam. Allowing for quicker acquisition time, we plan to use single-shot ptychography, where several partially overlapping laser beams will illuminate an object simultaneously. Similar to ptychography, for single-shot ptychography, we will use sophisticated phase retrieval algorithms to reconstruct the phase and amplitude of the object based on the information in the diffraction data we obtain. Since we will be working with ultrafast x-ray beams, we will use the Talbot wavefront sensor to monitor the x-ray beam incident on the object, thus ensuring that the beam is operating as expected. Characterization of the beam, together with the knowledge of how materials behave under extreme conditions, will enable us to create better materials for fusion energy. [Preview Abstract] |
Friday, October 23, 2020 11:42AM - 11:54AM Live |
B03.00006: ~Coherent Diffraction Imaging and Sample Characterization Landon Schnebly, Richard Sandberg We seek to use x-ray coherent diffraction imaging (CDI) to study how things break at the nanometer scale. Computer simulations using Fourier transforms and their inverse were used to simulate diffraction and highlight the importance of a priori information in retrieving the complex image of a sample. A physical sample of gold nanoparticle clusters on a sapphire substrate was then characterized using electron backscatter diffraction in order to identify interesting sites and retrieve surface level information. After applying stress by heating the sample to 700 degrees Celsius, the sites were imaged again and some evidence of annealing was present. Twin grain boundaries were identified as prime sites for CDI because their unique orientations allow for a support constraint of known values. The goal is to use the 3 dimensional reconstructive capabilities of CDI to analyze how a material's atomic lattice surrounding these boundaries or other defects shifts when stress is applied. [Preview Abstract] |
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