Browsing by Author "Kim, Seongsin M."
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Item Development of a Photonic Link for Enhancements in Quantum Applications(University of Alabama Libraries, 2024) Moseley, Carson; Kung, PatrickQuantum computing leverages the laws of quantum mechanics to process information and solve complex problems at levels that classical computers can't attain. However, its hardware implementation remains challenging due to environmental constraints. To address these concerns, this work explores the use of a photonic link to alleviate the thermal load associated with traditional cryogenic qubit control methods. The development and testing of two separate photonic links is covered, as well as the design and validation of a system to address nitrogen-vacancy centers in diamondItem Impact of Substrate and Bright Resonances on Group Velocity in Metamaterial without Dark Resonator(Nature Portfolio, 2015) Hokmabadi, Mohammad Parvinnezhad; Kim, Jy-Hyung; Rivera, Elmer; Kung, Patrick; Kim, Seongsin M.; University of Alabama TuscaloosaManipulating the speed of light has never been more exciting since electromagnetic induced transparency and its classical analogs led to slow light. Here, we report the manipulation of light group velocity in a terahertz metamaterial without needing a dark resonator, but utilizing instead two concentric split-ring bright resonators (meta-atoms) exhibiting a bright Fano resonance in close vicinity of a bright Lorentzian resonance to create a narrowband transmittance. Unlike earlier reports, the bright Fano resonance does not stem from an asymmetry of meta-atoms or an interaction between them. Additionally, we develop a method to determine the metamaterial "effective thickness", which quantifies the influence of the substrate on the metamaterial response and has remained challenging to estimate so far. By doing so, very good agreement between simulated and measured group delays and velocities is accomplished. The proposed structure and method will be useful in designing optical buffers, delay lines, and ultra-sensitive sensors.Item Investigation of Microwave Transducer for Linearity Dependence and Applications in Quantum Networking(University of Alabama Libraries, 2022) Bolton, Summer Alexis; Kim, Seongsin M.; Kung, Patrick; University of Alabama TuscaloosaQuantum devices have the potential to revolutionize applications in computing, communications, and sensing; however, current state-of-art resources must operate at extremely low temperatures. There is an increasing interest in optical fiber transduction to microwave link with superconducting and Si qubits. The quality depends strongly on the characteristics of the photodiode, specifically uni-traveling carrier photodiodes (UTC-PDs) for high-frequency operation, yet most do not have the high-speed and high-linearity performance or the ability to handle ultracold temperatures. To address these low-temperature and high-frequency problems, an RF photonic microwave transducer is used to measure the frequency response and investigate the linearity dependence on frequency, bias voltage, and temperature. An electro-optical microwave transducer is created using the heterodyning beat method. A high-speed MUTC photodiode designed for cryogenic temperatures is tested as the transducer and characterized with a spectrum analyzer. The linearity of the device is also tested at bias voltages of 0 V and −5 V, frequencies of 3 GHz and 10 GHz, and temperatures of 300 K and 77 K. With a low bias voltage, the frequency response shows a decrease in power due to the increase of harmonic noise. The results show that the linearity does depend on frequency, bias voltage, and temperature. A higher reverse bias voltage showed the highest 1-dB compression point, while a bias voltage of 0 V and a frequency of 10 GHz showed the lowest power and the lowest 1-dB compression point. Our results should help contribute to the future design of highly linear cryogenic quantum links.Item Mieczyslaw Weinberg: violin and piano Sonata no. 3 op. 37 and no. 5 op. 53(University of Alabama Libraries, 2020) Suarez, Silvia; Grégoire, Jenny; Noffsinger, Jonathan; University of Alabama TuscaloosaComposer Mieczyslaw Weinberg (1919 – 1996) wrote six sonatas for violin and piano, and three sonatas for solo violin, as well as an extensive number of chamber music, symphonic, vocal, and instrumental works. There is very little written on Weinberg’s violin and piano sonatas. The technical challenges and creative musical language employed in these works make them worthy of being studied, investigated, and added to the standard violin and piano chamber music repertoire. For this project I will write about the Sonatas no. 3 op. 37 (1947), and no. 5, op. 53 (1953) of Mieczyslaw Weinberg. I will also discuss Jewish influences and Shostakovich’s influences on Weinberg’s life and compositional style. To support this research, I will include excerpts from the scores to analyze Weinberg’s musical language. The performance of these two works will take place in the Spring of 2020 in conjunction with my final manuscript.Item Plasmon-Induced Transparency by Hybridizing Concentric-Twisted Double Split Ring Resonators(Nature Portfolio, 2015) Hokmabadi, Mohammad Parvinnezhad; Philip, Elizabath; Rivera, Elmer; Kung, Patrick; Kim, Seongsin M.; University of Alabama TuscaloosaAs a classical analogue of electromagnetically induced transparency, plasmon induced transparency (PIT) has attracted great attention by mitigating otherwise cumbersome experimental implementation constraints. Here, through theoretical design, simulation and experimental validation, we present a novel approach to achieve and control PIT by hybridizing two double split ring resonators (DSRRs) on flexible polyimide substrates. In the design, the large rings in the DSRRs are stationary and mirror images of each other, while the small SRRs rotate about their center axes. Counter-directional rotation (twisting) of the small SRRs is shown to lead to resonance shifts, while co-directional rotation results in splitting of the lower frequency resonance and emergence of a PIT window. We develop an equivalent circuit model and introduce a mutual inductance parameter M whose sign is shown to characterize the existence or absence of PIT response from the structure. This model attempts to provide a quantitative measure of the physical mechanisms underlying the observed PIT phenomenon. As such, our findings can support the design of several applications such as optical buffers, delay lines, and ultra-sensitive sensors.Item Strong Solar Radiation Forces from Anomalously Reflecting Metasurfaces for Solar Sail Attitude Control(Nature Portfolio, 2018) Ullery, Dylan C.; Soleymani, Sina; Heaton, Andrew; Orphee, Juan; Johnson, Les; Sood, Rohan; Kung, Patrick; Kim, Seongsin M.; University of Alabama Tuscaloosa; National Aeronautics & Space Administration (NASA)We examine the theoretical implications of incorporating metasurfaces on solar sails, and the effect they can have on the forces applied to the sail. This would enable a significant enhancement over state-of-the-art attitude control by demonstrating a novel, propellant-free and low-mass approach to induce a roll torque on the sail, which is a current limitation in present state-of-the-art technology. We do so by utilizing anomalous optical reflections from the metasurfaces to generate a net in-plane lateral force, which can lead to a net torque along the roll axis of the sail, in addition to the other spatial movements exhibited by the sail from solar radiation pressure. We characterize this net lateral force as a function of incidence angle. In addition, the influence of the phase gradients and anomalous conversion efficiencies characteristics of the metasurfaces are independently considered. The optimum incidence angle that corresponded with the maximum net lateral-to-normal force ratio was found to be -30 degrees for a metasurface exhibiting 75% anomalous conversion efficiency with a phase gradient of 0:71k(0).Item Terahertz Polarizers: from Flexible Metamaterials to Tunable Meta-Devices(University of Alabama Libraries, 2021) Philip, Elizabath; Kim, Seongsin M.; University of Alabama TuscaloosaSeveral of the unprecedented advancements in terahertz spectroscopy and imaging can be elucidated by the incorporation of polarization studies into their characterization mechanisms. However, these characterization systems are constantly developing, and as a result, are currently needing to replace their conventional terahertz polarization converters that are bulky and expensive. Consequently, this research work aims to develop metamaterial-based polarization converters that are compact, easy to fabricate, and versatile replacements to the traditional terahertz polarizers. We first explore a flexible, reflective metamaterial with two concentric ring structures demonstrating stereoisomeric properties. By modulating the lateral displacement of the concentric rings, we tune the polarization-dependent absorption properties of this stereo-metamaterial. More importantly, by inducing this spatially modulated structural asymmetry, we elicit linear-to-elliptical polarization conversion and pure optical rotation properties of the device. Six different spatial orientations of the stereo-metamaterial are analyzed through simulations and successfully verified experimentally. Of the six stereo-metamaterials, the one with the largest polarization conversion capability is leveraged to modify it into an actively tunable quarter-waveplates for low terahertz frequencies. Converting the passive stereo-metamaterial into an active device gives it the versatility needed for real-life application. We augment the stereo-metamaterial with liquid crystal to exploit its voltage-dependent birefringence property. Two distinct biasing techniques— an in-plane switching mode of biasing using interdigitated electrodes, and a homogeneous mode of biasing using transparent graphene electrodes are evaluated in detail. Both meta-devices exhibit great success as proof-of-concept devices. The in-plane switching mode of biasing offers polarization-dependent circular polarization conversion with moderate tunability. The limitations of the in-plane switching mode of biasing are circumvented using the graphene electrode-based homogeneous mode of biasing. Consequently, the meta-device using graphene electrodes manifests remarkable results in terms of its tunability and multifunctionality as — a quarter-waveplate, half-waveplate, linear rotator, and broadband linear-to-elliptical polarization converter. All three devices exude significant potential at expanding the frontiers of THz polarization conversion and influencing the fields of THz polarization spectroscopy and imaging, THz circular dichroism spectroscopy, and even THz communication.Item Ultra-High Efficiency and Broad Band Operation of Infrared Metasurface Anomalous Reflector based on Graphene Plasmonics(Nature Portfolio, 2019) Soleymani, Sina; Gungordu, M. Zeki; Kung, Patrick; Kim, Seongsin M.; University of Alabama TuscaloosaInfrared metasurface anomalous reflector with ultra-high efficiency and broad band operation is designed via multi-sheet graphene layer with triangular holes. The anomalous reflection angle covers the range of 10 degrees to 90 degrees with the efficiency higher than 80%, over a broad spectral range from 7 mu m-40 mu m of infrared spectrum. It reaches above 92% at the center wavelength in the spectral response. By increasing the periodicity of phase gradient, we can expand this frequency band even further without losing efficiency. The compact design of metasurface affords the adjustability of the electrochemical potential level of graphene by means of gating. Additionally, the impact of the number of graphene sheets for the optimum efficiency of the proposed structure is investigated. By adding the secondary graphene metasurface with opposite direction of phase gradient, we demonstrated the tunability of the reflection angle from 0(r) to - 0(r) with bias voltage.