Bulletin of the American Physical Society
APS March Meeting 2021
Monday–Friday, March 15–19, 2021; Virtual; Time Zone: Central Daylight Time, USA
Session A36: Undergraduate Research I: AMO and Optical TechniquesLive Undergrad Friendly

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Sponsoring Units: APS/SPS Chair: Chih Kuan Tung 
Monday, March 15, 2021 8:00AM  8:12AM Live 
A36.00001: Experimental Studies of the Near Field Enhancement Properties of Metal Resonators for Nonlinear THz Experiments Andrea Perry, Azel Murzabekova, Alexander Littlefield, Lynford Goddard, Fahad Mahmood Developing broadband sources of electromagnetic radiation in the terahertz (THz) frequency range is of current interest for studying novel magnetic phases of matter by directly coupling to the spin degrees of freedom over their intrinsic energy scale [1]. For optical studies in the nonlinear regime, sufficient THz field strengths have typically only been achieved in superradiant linear accelerators or lowgain freeelectron lasers [2]. Micronscale metal antennas offer nearfield enhancement of the incident THz field by orders of magnitude, providing tabletop sources of intense THz radiation [3]. However, experimentally verifying the field enhancement from such antennas proves challenging. We present experimental studies of the field enhancement in photolithographicallypatterned metallic antennas. This work provides insight into the enhancement properties of resonant metal structures and enables tabletop nonlinear THz experiments. 
Monday, March 15, 2021 8:12AM  8:24AM Live 
A36.00002: Twodimensional Superconducting Multimode Resonators for Surface Loss Extraction Youqi Gang, Xuan Hoang Le, Alexander Place, Nathalie De Leon, Andrew Houck Recent advancements in superconducting qubit coherence times by switching to tantalum capacitors demonstrates that understanding and improving materials is indispensable toward creating quantum processors. Superconducting microwave resonators have been widely used to study the materials losses in superconducting circuits, especially losses due to interface dielectrics. However, demonstrated methods for surface loss extraction require processing steps that are not used in, and thus not representative of, stateoftheart fabrication procedures. In this talk we present a set of twodimensional multimode resonators on sapphire that can be used to extract interface dielectric losses locally and with small uncertainty. By using slotline mode and nested structures of conventional resonator geometries, we can obtain a wellconditioned participation ratio matrix for different modes that accurately identifies the most lossy interface. Our design can be used to guide improvements in qubit fabrication. 
Monday, March 15, 2021 8:24AM  8:36AM 
A36.00003: Enhancing OpticsBased Detection of Semiconductor Patterning Defects Using Convolutional Neural Networks Bryan M Barnes, Martin Y. Sohn, Abdul Qadeer Rehan Semiconductor patterning defects have technological and financial consequences in nanoelectronics fabrication. 
Monday, March 15, 2021 8:36AM  8:48AM Live 
A36.00004: Gold nanoantennae and ENZ metamaterials for nonlinear optical effects Anna Shelton, Mariama Rebello Negative refraction is a phenomenon in which light exits the interface between two materials with different refractive indices at an angle negative relative to the normal. The coupling of Epsilon Near Zero (ENZ) thin films and gold nanoantennae show promise in creating metamaterials with negative effective refractive indices (neff) and strong nonlinear effects near the ENZ regime. The high surface energy density necessary for negative refraction is achieved when the localized surface plasmon polariton (LSPP) of the gold nanoantennae are tuned to the mode of an ENZ material. In this work, we simulated six gold nanorod ENZ metamaterials near the ENZ wavelength, where the real part of the permittivity of the ENZ material crossed zero, using the finitedifference timedomain method. We found that wellcoupled gold nanorod metamaterial systems enhanced the surface energy density in the ENZ metamaterials by two orders of magnitude, whereas ENZ film alone saw no magnification of incident light. The large enhancement of energy density via LSPP in metamaterials makes negative refraction more likely to occur, making the system ENZ/nanoparticles the best candidates for near field superlensing. 
Monday, March 15, 2021 8:48AM  9:00AM Live 
A36.00005: Using Static Light Scattering (SLS) to Determine the Structure of Polymeric Microgels Andrew Scherer, Samantha Tietjen, Kiril Streletzky We synthesized polysaccharide microgels with varying crosslinker concentrations, resulting in particles with different temperature dependent structure and dynamics depending on the crosslinker concentration. At least three behavioral regimes were observed in the microgel volume phase transition. It was found that with the increase of solution temperature microgels deswelled at low crosslinker, grew in size at high crosslinker, and showed a transitional behavior at intermediate crosslinker concentration. We studied structure of the microgels in each behavioral regime through SLS. The SLS data was analyzed using Zimm and Berry plots both above and below the volume phase transition yielding molecular weight, radius of gyration, and second virial coefficient. The SLS form factors were obtained and analyzed (e.g. using Kratky plots) both below and above the transition. Apparent and contrasting changes in the form factors were observed in different regimes during the transition. The applicability of common form factor models to the microgels in different regimes was considered. The measured form factors were also fit with various models (including hard and fuzzy sphere) by varying size parameters to determine analytically best structure describing the microgel SLS data. 
Monday, March 15, 2021 9:00AM  9:12AM Live 
A36.00006: Interferometric Measurement of Stochastic Pathlength Fluctuations in an Interferometer aimed at Optical Fouriertransform Spectroscopy Jiahao Jiang, Krishna H Patel, Christopher Smallwood Optical interferometers are the workhorse components of many different forms of Fouriertransform spectroscopy, including Fouriertransform infrared spectroscopy (FTIR), twopulse correlation spectroscopy, and multidimensional coherent spectroscopy (MDCS). In order for these elements to function properly in devices, it is vital that the random fluctuations in the associated interferometric optical path lengths be either actively eliminated or passively measured and subtracted out from the final data so that signals of interest can be separated from noise. In this research project, we report a dualphase measurement of optical path length noise in a MachZehnder interferometer incorporating homebuilt photodetectors and fieldprogrammable gate array (FPGA)based analogtodigital signal converters. We use the setup to monitor the effect of ambient laboratory temperature fluctuations on interferometer dimensions, extracting an optical table’s thermal expansion coefficient in the process. 
Monday, March 15, 2021 9:12AM  9:24AM Live 
A36.00007: Interferometer Networks Benjamin Krawciw, Cecilia Behn, Lincoln D Carr My work has been to generalize complex network theory further, giving it the ability to describe complex networks with interference. I did this by working with complex networks whose edges have complexnumber weights and solving the systems of equations those networks describe. This has proven to be a useful notation for describing interferometers, and I have used it to rederive the Michelson interferometer and the Sagnac Effect. To work with interferometer networks, I had to generalize the concepts of degree, clustering, and path length. Using these tools, I have analyzed complex generalizations of random networks, WattsStrogatz networks, and the Kuramoto Model. Random networks have average complex network measures near zero and always converge to a stable solution when a system of equations was solved on their complex adjacency matrix. WattsStrogatz networks and Complex Kuramoto models have network measures that depend on their input parameters, and certain choices create systems with no stable solution, which perpetually oscillate when solved numerically. More investigation is needed to determine how those complex network measures relate to instability, and what kind of network structure is necessary to create this instability. 
Monday, March 15, 2021 9:24AM  9:36AM Live 
A36.00008: Longwavelength, coherent injector GaAs/AlGaAs quantum cascade lasers Misael Campos, Ming Lyu, Loren Pfeiffer, Claire Gmachl We report on the design, fabrication, and characterization of GaAs/AlGaAs quantum cascade (QC) lasers with an emission wavelength in the range of 12 to 16 μm. Quantum cascade lasers in this wavelength range are of major interest for the creation of sensors to detect carcinogenic trace gases such as xylene, benzene, or toluene, which are released during the combustion of gasoline and forest fires. GaAs/AlGaAs is the material of choice for these designs despite the prevalence and greater understanding of InGaAs/AlInAs because the InP substrate on which InGaAs/AlInAs designs are grown has a large twophonon absorption near 16μm, hindering and even preventing high performance InGaAs/AlInAs QC lasers in the target wavelength range. To achieve highpower performance, the coherent injector behavior exhibited by a wellresearched In_{0.53}Ga_{0.47}As/Al_{0.52}In_{0.48}As QC laser structure was successfully recreated in GaAs/Al_{0.33}Ga_{0.67}As via simulations of a Schrödinger solver. This GaAs/Al_{0.33}Ga_{0.67}As QC laser has a designed emission wavelength of 12.4 μm; and, indeed, initial experiments show an electroluminescence wavelength of 12.0 ± 0.8 μm. Further experiments will determine whether the structure lases and future designs are scaling the wavelength to 16 μm. 
Monday, March 15, 2021 9:36AM  9:48AM Live 
A36.00009: Machine Learning with Temperature Sensing Quantum Dots Data Marissa Iraca Building from previous research of Cadmium Telluride (CdTe) quantum dots (QD) that emit at 520 nm, a CdTe QD sample that emits at slightly more than 790 nm was studied. By recording photoluminescent (PL) data and corresponding temperature at which light was emitted, we were able to train a neural network that takes the PL as an input and outputs the corresponding temperature within 0.599 K mean absolute error. 
Monday, March 15, 2021 9:48AM  10:00AM Live 
A36.00010: Fast Quantum Control of BoseEinstein Condensates for Inertial Sensing Applications Skyler A Wright, Chris Larson, Edward Carlo C Samson We report on our numerical simulations of highfidelity, fast quantum control of BoseEinstein condensates (BECs) as we study the viability of using shortcutstoadiabaticity (STA) launching protocols for BEC transport and for use in applications of inertial sensing interferometry in 2D. Arbitrary and dynamic painting potentials are used to confine and control the spatial transport of the BECs. Counterdiabatic driving STA protocols are used because they provide fast quantum control while suppressing excitations from free energies. Our preliminary simulations address how STA protocols compare with more classical approaches to transport in terms of quantum coherence based on the depth of the potential trap used and the total time of transport. Using these tests as a baseline, we analyze the effects of STA protocols when used in BEC MachZehnder interferometry. 
Monday, March 15, 2021 10:00AM  10:12AM Live 
A36.00011: Temperature dependence of the index of refraction of TOPAS cyclic olefin copolymer in the terahertz range Timothy Kritzell, Rebekah Smith, Nicholas Crescimanno, Matthew T Warren, Daniel Michael Heligman, Thuc Mai, Evan Jasper, Frank C Peiris, Rolando Valdes Aguilar Past measurements on the cyclic olefin copolymer TOPAS reveal a spectrallyflat refractive index within the terahertz range, giving the material exciting potential applications in optical apparatuses. Here we use THz spectroscopy to expand the understood frequency range, and as a probe to extract information regarding the temperature dependence of the refractive index, in which we find that the index of refraction increases with decreasing temperature. In hopes to understand this counterintuitive behavior, we report the temperature dependence of the reflectivity due to vibrational modes within the CH band via FTIR. Doing so, we find a similarly reversed behavior in which the excitation energy of some of the vibrational modes seems to increase with temperature, providing a puzzling departure from expected behaviors. 
Monday, March 15, 2021 10:12AM  10:24AM Live 
A36.00012: Eikonal approximation in electromagnetic scattering Avinash Khatri, K. V. Shajesh, Dipanjan Mazumdar Eikonal approximation, which uses the laws of geometrical optics, has been used in the study of scattering theories for over a century. Although eikonal approximation originated in the field of optics and electromagnetism, it has been extensively used in quantum mechanics and quantum field theories in the form of a closely related WKB approximation. Eikonal approximation is an uncontrolled approximation and often fails to give an unambiguous nexttoleading order contribution. The region of validity of eikonal approximation has not been explored well and this motivates us to explore its validity regime. In this work, we revisit the scattering of a monochromatic wave through a weak dielectric sphere to understand the validity of the eikonal approximation in electromagnetism. Scattering of a monochromatic wave through a weak dielectric sphere is exactly solvable and we compare the total crosssection calculated using the exact method with the eikonal approximation. We expect our work will highlight the regime of validity under which eikonal approximation gives a precise nexttoleading order contribution. 
Monday, March 15, 2021 10:24AM  10:36AM Live 
A36.00013: Developing a network of synthetically coupled mechanical oscillators to demonstrate topological effects. Yaashnaa Singhal, Ritika Anandwade, Ellen Carlson, Michael Castle, Sai Paladugu, Bryce Gadway The exchange of energy between harmonic oscillators coupled in a network provides a mechanical analog for the exploration of lattice transport phenomena relevant to condensed matter physics. Using accelerometerbased position monitoring and external driving by magnetic fields, we implement a new platform of synthetic mechanical network in which oscillators can be tuned and coupled through a remote feedbackcontrol system. We will discuss how this approach enables the control of tunneling phases and artificial gauge fields, and we will present preliminary experimental results on the implementation of this approach. 
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