Bulletin of the American Physical Society
Joint Fall 2021 Meeting of the Texas Sections of APS, AAPT, and SPS
Volume 66, Number 10
Thursday–Saturday, October 21–23, 2021; Houston; Central Time
Session T02: Atomic, Molecular, and Optical Physics II |
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Chair: Rebecca Forrest, UH Room: STEM 2105 |
Saturday, October 23, 2021 10:00AM - 10:36AM |
T02.00001: Exact Solutions of the Time-Independent Schr$\ddot {\rm o}$dinger and Gross-Pitaevskii Equations Invited Speaker: Mark Novotny A prescription is given to obtain some exact results for certain external potentials $V\left({\vec r}\right)$ of the time-independent Schr$\ddot{\rm o}$dinger equation and Gross-Pitaevskii (non-linear Schr$\ddot{\rm o}$dinger) equation. The study is motivated by the ability to program $V\left({\vec r}\right)$ experimentally in Bose-Einstein condensates (BEC). The company ColdQuanta has developed the first generation of such a machine, and a BEC has been made and measured on the International Space Station. The BEC ground state is, under certain assumptions, modeled using the Gross-Pitaevskii equation. We present several examples of these two equations in 1D (one dimension) including the Gaussian, Lorentzian, Gumbel, logistic, Rayleigh, chi, and beta pdfs (probability distribution functions). The Gaussian pdf is obtained from the groundstate wavefunction that is the solution of the Schr$\ddot{\rm o}$dinger equation in a simple harmonic oscillator potential. Examples in 2D and 3D are also presented, including for the hydrogen atom in momentum space. [Preview Abstract] |
Saturday, October 23, 2021 10:36AM - 10:48AM |
T02.00002: Comparing the Born-Oppenheimer Approximation and Fully Nonadiabatic Calculations Steve Alexander, R.L. Coldwell Using Variational Monte Carlo methods we have calculated Born-Oppenheimer energies for the H2$+$ molecular ion at several internuclear distances. With these we then construct the potential curve and the lowest several rovibrational energies. Using the trial wavefunctions at each internuclear distance we also evaluate both the diagnonal and non-diagonal corrections to the Born-Oppenheimer approximation. These corrections are then added to the Born-Oppenheimer energies to produce more accurate estimates for the lowest several rovibrational energies. We compare the results of each level of approximation with results obtained from a fully-nonadiabatic wavefunction. [Preview Abstract] |
Saturday, October 23, 2021 10:48AM - 11:00AM |
T02.00003: Dependence of Photon Entanglement on Coincidence Window Size Sarah Darbar, Emily Padilla We investigated the properties of entangled photon pairs as a function of the coincidence window size in an experiment with a type-I parametric down conversion source. We verified that, for coincidence windows below 10 ns, the prepared Bell states exhibited a visibility of over 95\%. We furthermore observed a violation of the Bell-CHSH inequality but only for coincidence windows below 25 ns. These results show the significant implications for choosing windows for coincidence detections, since both our measured visibilities and Bell statistic parameters decreased for larger windows. We hypothesize that for larger coincidence windows there is more of a likelihood for either dark counts or additional photons from our entanglement source to set off coincidence detections. In reality, these may not be actual coincidence counts from a single pair of entangled photons. This may imply that an increased window may show more of a classical representation for our state than a quantum one. [Preview Abstract] |
Saturday, October 23, 2021 11:00AM - 11:12AM |
T02.00004: The Effect of Laser Power on the Fidelity of a Polarized State Cordell Mazzetti, Alejandro Villalobos For experimentalists measuring polarization states using Quantum State Tomography, the fidelity of the measured state reflects the success in recreating an ideal state. Errors in alignment and collimation can drastically affect this fidelity. Another variable that can affect this fidelity is the intensity of light or, equivalently, the rate of photons sent into an experimental setup. Using an experimental setup with attenuated laser light that can prepare states of polarized light with fidelities of up to 0.99, we found that by varying the intensity of light, the fidelity ranged from 0.25 to 1.0. Our results showed that for a single-photon counter module capable of measuring up to 500,000 photons per second, with the dark count rate around 330 Hz, the photon count rate that yielded the best fidelities sat around 31000 to 94000 photons per second. The data we collected also showed that, as photon counts increased, the standard basis states, on average, maintained higher fidelities than mixed states but were more likely to have fidelities that fell below 0.5. This discrepancy was likely due to the large differences in horizontal and vertical components of the basis states as the single-photon counter modules became oversaturated. [Preview Abstract] |
Saturday, October 23, 2021 11:12AM - 11:24AM |
T02.00005: Optical vortex efficiency of envelope varying gratings using high-phase modulation spatial light modulators. Edward Sanchez, Sachin Sharma, Ioannis Chatzakis Spatial light modulators used for diffraction and to induce angular momentum in laser beams has been studied extensively by various teams. Missing in the literature is a systematic analysis of how varying the envelope of the grating can affect the diffraction efficiency of SLMs, both for grating diffraction and for optical vortex generation. The work of Bowman shed light on how one can analyze the potential distortion of an SLM by viewing its phase unwrapping scheme, doing ones best to ensure this line is as linear as possible. Analysis of efficiency through phase unwrapped lines for each hologram has been applied to different grating envelopes. In specific, we have analyzed sinusoidal, sawtooth, triangle, and square envelopes and compared with experimental results. The results show that the sawtooth grating achieves the highest efficiency at a specific diffraction order. [Preview Abstract] |
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