Bulletin of the American Physical Society
APS March Meeting 2018
Volume 63, Number 1
Monday–Friday, March 5–9, 2018; Los Angeles, California
Session R08: Superconductors, Correlated Materials, Spectroscopic Observations |
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Sponsoring Units: DCMP Chair: Yizhou Xin, Northwestern University Room: LACC 153C |
Thursday, March 8, 2018 8:00AM - 8:12AM |
R08.00001: Fermi liquid - Non Fermi liquid transition in a holographic model for high temperature superconductors. Gaston Giordano, Nicolas Grandi, Adrian Lugo, Rodrigo Soto Garrido In a recent paper, Kiritsis and Li (JHEP01(2016)147) introduced a holographic model to study the competition between different order phases similar to the ones observed in high temperature superconductors (HTSC). Within their model, they found four different phases: the normal phase, the SC phase, the antiferromagnetic phase and a striped phase as a function of temperature and doping. In the present work, we introduce fermions to their holographic model and study the fermionic spectral functions in the normal phase (Non-SC phase) at zero and finite temperature. Combining analytic and numerical methods, we found that for a range of parameters of the model there is a crossover from a Landau Fermi liquid to a strange metallic phase (Non Fermi liquid) as the doping is decreased. |
Thursday, March 8, 2018 8:12AM - 8:24AM |
R08.00002: The Magnetic Field Dependence of the Light hole Transition and Mixing in a GaAs/AlGaAs Quantum Well from Optically Pumped NMR Sunil Thapa, Ryan Wood, Clifford Bowers, Matthew Willmering, Erika Sesti, Sophia Hayes, Arneil Reyes, Philip Kuhns, Stephen McGill, Christopher Stanton We present a theoretical interpretation of OPNMR (Optically Pumped NMR) measurements in undoped, lattice-matched Al0.31Ga0.69As/GaAs MQWs grown on (001) GaAs substrate subjected to transverse static magnetic field (B) varying between 1 to 12 T. An 8-band k.p band structure calculation is performed for the energy eigenvalues and band mixing probabilities using a finite-difference method. Using Fermi’s golden rule, inter-band absorption coefficients and conduction band spin-polarization are calculated as a function of photon energy for both σ+ and σ- optical helicities. The calculated band structure and transition probabilities aid in the understanding the origin of the OPNMR profile. We show that the strongest light hole transition for σ- absorption occurs at energies higher than the energies for transitions for σ+ absorption. The curvature seen in the B-dependence for the σ+ OPNMR profile is attributed to the strong Landau level mixing of the LH↓ (light hole down) with the HH↓ (heavy hole down) states. For the σ- absorption, a strong mixing of the LH↑ (light hole up) with the HH↓ states is seen in the B<6T regime. Finally, we discuss additional effects including excitons and self-consistent electric field that can improve the accuracy of the calculations with the experiments. |
Thursday, March 8, 2018 8:24AM - 8:36AM |
R08.00003: Fundamental limits to the secure key rate of quantum key distribution using Gaussian-modulated coherent states in the presence of quantum noise and device mismatch uncertainty SungWon Chung, Abhilash Ravindranath, Xi Yang High-speed quantum key distribution enables unconditionally secure communication, but has not been in widespread usage yet in part due to its slow secure data rate. By exploiting photonic integrated circuit technologies for near infrared wavelengths, continuous-variable quantum key distribution using Gaussian-modulated coherent states has been recently reported to operate at room temperature in a chip-scale realization. Nevertheless, the highest secure key rate achieved is still well below the multi-gigabit capability of conventional optical communication technologies. Measured noise characteristics of silicon transistors show that the fundamental limits to the secure key rate may come from the device mismatch uncertainty, which is inherent in the physical realization of a balanced optical quantum key distribution receiver for the detection of Gaussian-modulated coherent states. Here we discuss simulation results on a programmable silicon quantum photonic integrated circuit, predicting that the programmability can mitigate the impact of device mismatch and thus a multi-gigabit/sec secure key rate will be achieved in line-of-sight free-space optical quantum channels and short-distance fiber channels. |
Thursday, March 8, 2018 8:36AM - 8:48AM |
R08.00004: Phonon Mediated Optical Stark Effect for Inorganic-Organic Hybrid Heterostructures Que Huong Nguyen Phonon mediated optical Stark effect for organic-semiconductor heterostructures (the quantum well, the system of quantum dots) with existence of hybrid Wannier-Frenkel excitons will be studied theoretically and modelled numerically, taking into account in the macroscopic phonoriton equations the two-component exciton state. |
Thursday, March 8, 2018 8:48AM - 9:00AM |
R08.00005: Characterization of rare earth elements by laser-induced breakdown spectroscopy Chet Bhatt Laser-induced breakdown spectroscopy (LIBS) is an emerging in situ analytical technique for material characterization. Qualitative and quantitative analyses of various rare earth elements (REEs) in three different types of samples by LIBS is demonstrated. Firstly, analysis of six rare earth elements [cerium (Ce), europium (Eu), gadolinium (Gd), neodymium (Nd), samarium (Sm), and yttrium (Y)] have been performed using standard samples. Natural geological samples with low concentration of REEs were used for the LIBS study in the second part. Low and high intensity spectral signals of Ce, La, Nd, Y, Pr, Sm, Eu, Gd, and Dy were detected and multivariate analysis was executed by developing partial least squares regression (PLS-R) models for the quantification of Ce, La, and Nd. After studying REEs in standard and natural geological samples in powder form, two rare earth elements (Eu and Yb) in aqueous solutions were studied at ambient and high-pressure conditions. |
Thursday, March 8, 2018 9:00AM - 9:12AM |
R08.00006: Kβ1,3 x-ray emission spectra in the elements from Ca to Ge Yoshiaki Ito, Tatsunori Tochio, Michiru Yamashita, Sei Fukushima, Aurel Vlaicu, Katarzyna Slabkowska, Lukasz Syrocki, Ewa Weder, Marek Polasik, Kinga Sawicka, Paul Indelicato, Jose Marques, Maria Martins, Fernando Parente, Jose Santo The Kβ1,3, Kβ' and Kβ" spectra in the elements from Ca to Ge were systematically investigated using a high-resolution anti-parallel double-crystal x-ray spectrometer. Each Kβ1,3 natural linewidth was corrected using the instrumental function of this type of x-ray spetrometer and the spin doublet energies were obtained from the peak position values in 3d Kβ1,3 spectra. The width of the Kβ1 spectra linearly increases with the 3d elements. However, that of the Kb3 spectra is not linear in 3d elements and increased from Sc to Ni elements by around 0.5 eV. The contribution of Kβ' and Kβ" satellites is considered to be [KM] shake processes. From the calculation of Ca, Cu and Zn Kβ1,3 spectra, [KM] shake processes are mainly contributed to the Kβ1,3 spectra. |
Thursday, March 8, 2018 9:12AM - 9:24AM |
R08.00007: A Novel Design of Thermally Activated Delayed Fluorescence Molecules: Experimental and Computational Studies. Ramin Ansari, MOUNGGON Kim, SEONG JUN YOON, Daniel Hashemi, Jinsang Kim, John Kieffer In an organic light emitting diode (OLED), electrically injected charge carriers form singlet and triplet excitons in a 1:3 ratio. The goal of OLED research is to overcome the limitation imposed by forbidden decay from triplet states. One approach is to enhance T1 to S1 reverse intersystem crossing (ISC) by carefully designing organic molecules that exhibit a small energy gap (EST) between S1 and T1 levels. This allows for non-radiative triplet states to up-convert to radiative singlet states, a process called thermally activated delayed fluorescence (TADF). One strategy to minimize EST is to configure molecules in a donor-acceptor (D-A) electronic alternation. However, this may cause geometric changes in molecular conformation, resulting in low quantum yields and a broad emission. By synergistically combining experiments and simulation, we were able to design novel TADF emitting molecules based on the donor-acceptor-donor (D-A) concept, but where the in molecular conformation change is successfully suppressed, leading to higher electroluminescence efficiencies and sharp emissions. This design can guide the development of future TADF organic molecules. |
Thursday, March 8, 2018 9:24AM - 9:36AM |
R08.00008: Abstract Withdrawn
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(Author Not Attending)
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R08.00009: Analysis of sensors to detect the planetary boundary value of atmospheric aerosol loading caused by anthropocentric activities. Arpan Sharma As per Rockstrom, many thresholds have been crossed by the anthropocentric activities. These thresholds are called as planetary boundaries. The atmospheric aerosol loading is one of the thresholds, but its proper value is not determined entirely. This paper firstly explains the social and scientific reasons and later on analyses various technologies that can detect the aerosol loadings. One of the technology being NASA’s MODIS (Moderate Resolution Imaging Spectroradiometer) on Terra and Aqua satellites. The recent finding from this sensor has suggested that there is a decrease in atmospheric aerosol loading in North American Monsoon and so on. The variation of the atmospheric aerosol loading over various areas has also been discussed so that its impact on the climate is understood. |
Thursday, March 8, 2018 9:48AM - 10:00AM |
R08.00010: Development of mm-wave sensors for measurements of the Cosmic Microwave Background Trupti Khaire, Faustin Carter, Evan Mayer, Junjia Ding, Chrystian Posada, Volodymyr Yefremenko, Steve Padin, John Carlstrom, Clarence Chang, Valentyn Novosad In the process of developing superconducting sensor technology for the next generation of Cosmic Microwave Background (CMB) experiments, we have been working on a design that couples the CMB signal from a microstrip antenna to transition edge sensors (TES). In our detector design, the signal from the microstrip antenna is split into passbands centered at 95 GHz, 150 GHz and 220 GHz [1,2], and is then routed to different transition edge sensors. Making this possible in a compact topology requires crossover structures that isolate the high frequency superconducting lines from each other. Here, we will discuss the design optimization that replaces these superconducting cross-over structures with ground layer embedded cross-under structures. This change reduces the number of required depositions and circumvents liftoff issues associated with cross-over structures. In doing so, we had to ensure no cross talk in the high frequency lines, confirmed by HFSS simulation results. [1] C. M. Posada et al., Supercond. Sci. Technol. 28, 94002 (2015), [2] J. Ding et al., IEEE Trans. Appl. Supercond. 27, 2100204 (2017) |
Thursday, March 8, 2018 10:00AM - 10:12AM |
R08.00011: A New Form of Parallel Processing in Gravitational/Spacetime Exploration Kenneth Beck, Brianna Lee, Kelli Lee The LISA space probe has a first launch date projected for 2034. It may represent humanity's best attempt yet to undercover the basic workings of the Universe we inhabit. Our knowledge of a predictable four-dimensional spacetime will increase with hard work. In equal measure, our ignorance will also be exposed. As it must. Singularities and discontinuities may occur more or less frequently than we imagined. We will need new forms in space navigation as our probes record "the new realities" they encounter and even continue their mission, safely, and possibly return. Computing the transition and saddle points between, say, an elliptical and a parabolic orbit from Earth will become less possible. Set for over decades of study, instrument development, launch, perhaps assembly in space, the aim of LISA is to study gravitational waves, and particles in a myriad array of unknowns below 0.2 eV. Where we lack knowledge new forms will be developed to test our theories, numerically and rapidly. A proto-type only, based on the i5/i7 mixed iMac-mini cluster with detached memory with Thunderbolt 2 virtual interface has been assembled and tested , and put to work computing orbital dynamics. We present the results on this one form. |
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