Bulletin of the American Physical Society
APS March Meeting 2023
Volume 68, Number 3
Las Vegas, Nevada (March 5-10)
Virtual (March 20-22); Time Zone: Pacific Time
Session VV01: V: Poster Session III (7:00am-8:00am, PST)Poster Undergrad Friendly
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Room: Virtual Room 1 |
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VV01.00001: POLYMER PHYSICS | SOFT CONDENSED MATTER | STATISTICAL AND NONLINEAR PHYSICS | BIOLOGICAL PHYSICS . |
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VV01.00002: Design of stimuli-responsive materials from a diblock copolymer with association between dissimilar monomers Mingge Zhao, Xinyue Zhang, Junhan Cho Recently, stimuli-responsive materials have drawn tremendous attention due to their structures and properties and also due to their smart responses to changes in surrounding environment. In this work, we suggest the design of such materials based on associating A-b-B diblock copolymers. The free energy for the copolymer in the bulk state is first obtained as the perturbed hard sphere chains subject to adhesive potential between dissimilar monomers. Through Gaussian thread approach, the free energy functional is formulated to include effective local interactions from the excess equation of state. The random-phase approximation and self-consistent field analyses are to be readily elicited from the functional. It is demonstrated using these field approaches that the manipulation of disparity in self contact interactions and thermoreversibility of association can yield a variety of nasoscale mesophases upon cooling, heating, pressurization, and depressurization. In addition, micellization and reverse micellization in the solutions of the copolymer in selective solvents are to be probed via the manipulation of cross contact interactions and association. We will also discuss the applicability of such smart materials to various areas. |
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VV01.00003: Phase behaviors of a weakly charged stoichiometric polyanion/polycation blend with asymmetry in chain sizes and van der Waals interactions Xinyue Zhang, Mingge Zhao, Junhan Cho A study on the phase behaviors of a salt-free stoichiometric blend from weakly charged polyanions and polycations has been performed. A free energy functional for the blend is formulated as the sum of Gaussian contribution and effective interaction terms, whose local part is given by the excess equation of state for the blend and nonlocal part through Coulomb interactions. Then, the Landau free energy expansion is obtained as a series in component density fluctuations. Using the Landau energy, the blends with asymmetry in chain sizes and van der Waals interactions are probed at various charge fractions to analyze their nanoscopic phase separation due to global electroneutrality. The location of continuous transition and mesophase formation not only upon cooling but also upon heating are deeply investigated. In addition, the control of the equilibration of mesophases through pressurization is discussed in the viewpoint of designing stimuli-responsive structural materials from the polyelectrolyte blends. |
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VV01.00004: Structural Analysis of Uniaxially Oriented Polysaccharide Films under Humidity Conditioning Ayaka Yamaji, Go Matsuba, Kosuke Okeyoshi, Yuka Ikemoto The uniaxial oriented films were obtained by drying a highly viscous polysaccharide aqueous solution in a limited space. The molecules were arranged along the contact line of the solid-gas-liquid interface. Such alignment film fabrication technology is expected to lead to the development of sustainable materials that have both biocompatibility and environmental adaptability. For this purpose, it is significant to clarify the interaction between the oriented films and water molecules. In this study, we carried out IR spectroscopy and microscopy to understand structural change of uniaxially oriented films under humidity control. We focused on the synchrotron FT-IR spectroscopy. The spectra from the enol form in the amorphous oriented polysaccharide films depend on humidity, while the spectra were independent of humidity in the case of crystalline polysaccharide films. The results suggest that the processes of both water absorption and dehydration occur on the surface of the uniaxially amorphous oriented film. Therefore, the structural change of the amorphous polysaccharide film is greatly affected by humidity, but the crystalline polysaccharide film is not so affected. |
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VV01.00005: Binary Mixtures of Colloidal Cellulose Nanocrystals and Laponite for Preparation of Functional Nanocomposites Catherine Tom, Ravi Kumar Pujala Cellulose nanocrystals (CNCs) are attractive substances with interesting colloidal self-assembly behaviour and rheological properties due to their rigid rod morphology. Aqueous dispersion characteristics as well as the rheological, optical, and structural properties of binary mixtures of CNCs and Laponite (L) are investigated in detail. As the concentration of CNC increased, the interparticle distance decreased exhibiting excellent birefringent properties, which were confirmed by imaging the samples placed between cross polarizers. We obtain various complex structures by using the binary mixtures of CNCs and Laponite. A phase diagram consisting of sol, isotropic gel, and birefringent nematic gel phases is obtained. To go further, we demonstrate the fabrication of nanocomposite thin films and aerogels from the binary colloidal mixtures. For the former, they can be used as efficient absorbers of model pollutants such as Nile blue and Rhodamine B dyes in solution, while as-obtained aerogels display enhanced flame retardation behaviour. Our findings envisage that this system will serve as a model binary system of one and two dimensions with complex interactions. |
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VV01.00006: Streamings in confined active viscoelastic fluids Yuhao Wang, Yilin Wu Confined active matter systems exhibit rich ordering phenomena. A well-known example is bacterial active fluids, which can be stabilized from mesoscale turbulence to a mesoscale spiral vortex when confined. By adding viscoelastic polymers into bacterial active fluids, we previously found that such active viscoelastic fluids would display spatial and temporal ordering at macroscopic scales. Here we study how confinement geometry influences the behavior of viscoelastic bacterial active fluids. We found circulatory streaming in channel-like confinement that resembles biological cytoplasmic streaming with indifferent zones. The findings provide new insight into the control of active matter flows in artificial and biological settings. |
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VV01.00007: Non-monotonic behavior of timescales of passage in heterogenous media : Dependence on the nature of barriers Sougata Guha, Moumita Dasgupta, Leon Armbruster, Dibyendu Das, Mithun K Mitra Usually time of passage across a region maybe expected to increase with the number of barriers along the path. Can this intuition fail depending on the special nature of the barrier? We study experimentally the transport of a robotic bug which navigates through a spatially patterned array of obstacles. Depending on the nature of the obstacles we call them either entropic or energetic barriers. For the energetic barriers we find that the timescales of first passage vary non-monotonically with thenumber of barriers, while for entropic barriers first passage times increase monotonically. To explain this counter-intuitive phenomenon, we present analytically exact as well as simulation results of first passage times for different theoretical models of diffusion. We also show non-monotonic effective diffusivity in the case of energetic barriers. These results maybe relevant for timescales certain biological processes. |
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VV01.00008: Role of noise on directed motion of active particles on Ratchet Anshika Chugh, Rajaraman Ganesh The directed motion of a collection of Brownian particles is known to happen when temporal and spatial symmetries are broken in the system. There are different ways to break these symmetries[1]. Using asymmetric potential called Ratchet is one way to break spatial symmetry and by externally applying unbiased drive to break temporal symmetries one can observe ratchet effects in the system.[2] However, there exists a special kind of particle called active particles[3] which are inherently non-equilibrium in nature because of their ability to convert local energy into work. These particles are known to break the time-reversal symmetries at a particle level. |
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VV01.00009: A systems level approach to understanding the role of protein-mRNA droplets in meiotic exit Sima Setayeshgar, Renyu Wang, Soni Lacefield The complex cell division process of meiosis ensures the formation of haploid gametes through two rounds of chromosome segregation after one round of DNA replication. How cells limit meiosis to two and only two divisions is poorly understood. In budding yeast, autophagy degrades the RNA-binding protein Rim4 in meiosis II (Wang et al. Dev. Cell 52 (2020)), which has been shown to form aggregated fibrils that bind various mRNAs to prevent their translation. Liquid-liquid phase separated condensates consisting of key molecules together with other proteins or RNA have been shown to be important in the proper execution of a variety of cellular regulatory processes in a spatially and temporally controlled manner through different mechanisms. Several of the mRNAs bound by Rim4 encode important regulators of meiosis II and meiotic exit. Indeed, with inhibition of autophagy, Rim4-mRNA droplets persist and cells fail to exit meiosis properly. To investigate the role of Rim4-mRNA droplets in the regulation of meiotic exit, we have constructed a parsimonious model of meiotic termination. Combined with experimental analysis, we describe the dynamics of key constituents governing irreversible exit demonstrating good agreement between the model and experiments. Notably, we show how disruption of droplet disintegration could result in exit failure and continued cell-cycle oscillations. |
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VV01.00010: Mechanical signature of non-reciprocal dynamics in active self-assembly Arnab Saha, Mohammad Samsuzzaman An active particulate system bound within a circular external potential of varying steepness is studied in-silico. Individual particles interacting pair-wise via a soft repulsive potential are considered to align their velocities with the mean orientation of their immediate neighbours. Such alignment rule results into non-reciprocal forces which in turn is manifested into emergent collective motion. The steady state structural properties of this system has already been charted in detail in the activity-steepness parameter space. The system goes from a rotating disordered phase to a rolling ordered phase as a function Here, we focus on the dynamics of this system under mechanical quench of the confinement. In particular, we attempt to identify and quantify the onset of the non-reciprocal dynamical transition in terms of space-time correlations of mechanically relevant variables such as vorticity and positional fluctuations. |
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VV01.00011: CHEMICAL PHYSICS | ATOMIC, MOLECULAR, AND OPTICAL PHYSICS . |
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VV01.00012: Revealing the three-component structure of water with principal component analysis (PCA) on X-ray spectra Lei Xu, Zhipeng Jin Combining principal component analysis (PCA) of X-ray spectra with MD simulations, we experimentally reveal the existence of three basic components in water. These components exhibit distinct structures, densities, and temperature dependencies. Among the three, the two major components correspond to the low-density liquid (LDL) and the high-density liquid (HDL) predicted by the two-component model, and the third component exhibits a unique 5-hydrogen-bond configuration with ultra-high local density. As the temperature increases, the LDL component decreases and the HDL component increases, while the third component varies non-monotonically with a peak around 20 °C to 30 °C. The 3D structure of the third component is further illustrated as the uniform distribution of five hydrogen-bonded neighbors on a spherical surface. Our study reveals experimental evidence for water's possible three-component structure, which provides a fundamental basis for understanding water's special properties and anomalies [1]. |
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VV01.00013: Rate-equation approach for qudits Maksym Liul, Sergey Shevchenko Qubits (two-level quantum systems) play a key role in building and development of quantum computers. However, there are systems, which can enhance the efficiency of quantum algorithms and simplify the experimental setup, such systems are qudits (d-level quantum systems). In our research we theoretically investigate the influence of strong driving on one of such systems. The results can give appropriate information about ways of controlling and characterizing qudit states. One of possible tools for theoretical analysis of multi-level quantum systems properties is the rate-equation formalism. The great advantage of considered approach is its simplicity. Firstly we applied the formalism for description of a two-level system and then expanded it on a case of a multi-level system. Obtained theoretical results have good agreement with experiments [1, 2]. Also we compared rate-equation formalism with Lindblad equation approach and got good agreement between them. The presented approach can be considered as one additional way for exploring properties of quantum systems and underlying physical processes such as, for example, interference and Landau-Zener-Stuckelberg-Majorana transition. |
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VV01.00014: Collision-induced fragmentation of biomolecules inside an ion funnel UMA N N, Abheek Roy, Salvi M, Hemanth Dinesan, S Sunilkumar Ion funnels are radiofrequency (RF) devices used for the transmission of ions through a relatively high-pressure vacuum interface (typically 0.01 mbar - 10 mbar) [1]. They are made of ring electrodes with RF voltages of opposite polarity applied on successive electrodes for confining the ions radially, and a DC gradient for guiding the ions along the length of the device. The ring electrodes have reducing inner diameters toward the exit of the ion funnel so that the ions are effectively focused from the entrance to the exit of the device. They are routinely employed as a vacuum interface for electrospray ionization sources. It is known that the ion funnels could induce fragmentation of biomolecular ions generated in an electrospray ion source [2]. However, no systematic characterization of this process is not available in the literature. In this work, we study systematically the collision-induced fragmentation [3] of one of the building blocks of DNA while passing through an ion funnel. We show that the ion funnel parameters can be optimized to reduce the fragmentation process without sacrificing the total number of ions transmitted through the device. |
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VV01.00015: Simulation of non-Hermitian dynamics of many-body quantum systems Anant V Varma We investigate the complexity of simulating many-body non-Hermitian dynamics using the embedding method, as non-Hermitian systems do not exist in nature as closed systems. We show that simulation of even simplest many-body non-Hermitian system namely a system of N-free spin-1/2s or fermions would require a strongly correlated Hermitian system in higher dimensions, with a minimal dilation of Hilbert space. We further show that such highly interacting Hermitian system can be visualized as a central spin or fermion model and exhibit many-body features like orthogonality catastrophe. |
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VV01.00016: The charge transfer dynamics study for He+ - Diatoms interactions DEBOKI REJA Ion-molecule collisions are dominant processes in the interstellar (ISM) and interplanetary (IPM) medium [1]. Such collisions proceed through various elastic and inelastic channels. The study plays an immense role in astrophysics, especially in the cometary and planetary atmosphere, atmospheric physics, and plasma and fusion science. The collision study of major constituents of ISM and IPM ions such as H+, He+, and He2+ with minor neutral molecules (H2, CO, N2, NO, O2, and CO2) has gained a lot of interest due to its astrophysical relevance [2]. Solar wind ions move from 200 km/s to 700 km/s, showing charge exchange phenomena at the high collision energy [3]. Many experimental and theoretical studies have been carried out over the years to understand such phenomena [4-6]. The idea is to understand the interaction of ions present in the ISM and cometary atmosphere with the small molecules from the quantum mechanics perspective. Our work is focused on the ab initio quantum dynamics study of He+- diatom charge transfer (CT) reactions. The high ionization potential of He+ allows a large number of CT product channels accessible. We computed the adiabatic potential energy surface (PESs) and identified the respective product channels (entrance and CT). Several low-mixing excited electronic PESs also interact demanding the non-Born-Oppenheimer treatment for dynamical studies. The CT reactions seem to happen through nonadiabatic coupling between the PESs. Our current focus is on the theoretical development to study the several dynamical outcomes leading to CT in the systems.
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VV01.00017: Characterization of an experimental setup for ion transmission from atmospheric pressure to a 16-pole ion trap in high vacuum. Abheek Roy, Uma N N, Salvi M, Hemanth Dinesan, Sunil Kumar
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VV01.00018: Self-generation processes as stochastically embedded building mechanisms generating complex molecular chains and simple biological structures from single point spaces: Upgrading origin to both simple particle communities from simplest particles and livable simplest cells from complex molecular chains Taner Sengor A method is designed to explain how the simplest particle, SP that is least than the littlest particle builds particle communities, PCs. Such researches involve new precedencies for extracted particles, generally; however, the approach of single point spaces, sPSs overcomes such inconveniences. The method is a global infimum process relatable to sPSs and generates trapping states, TSs under quantum level governed by time energy, TE and extended black hole, EBH concepts. TSs have self-potential to build mechanisms, SP-BMs of SPs. SPs pass to PCs with global supremum processes. PCs pass to complex molecular chains, CMCs and CMCs pass to biological structures, BSs with electromagnetically equivalence processes, EEPs under suitable conditions. EEPs design conditions preparing SP-BMs for both CMCs and BSs, CMCs-BSs. EEPs are determined for both natural generation processes of CMCs-BSs from equations written with stochastically propagation processes related to TE and an approach equivalent to BH equivalently processes, BHePs in micro-millimeter range. |
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VV01.00019: TOPOLOGICAL MATERIALS | SEMICONDUCTORS, INSULATORS, AND DIELECTRICS . |
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VV01.00020: Symmetry-enforced nodal chain phonons Jiaojiao Zhu Topological phonons in crystalline materials have been attracting great interest. Most cases studied so far are direct generalizations of the topological states from electronic systems. Here, we reveal a class of topological phonons - the symmetry-enforced nodalchain phonons, which manifest the characteristic of phononic systems. We show that in five space groups with D2d little co-group at a non-time-reversal-invariant-momentum point, the phononic nodal chain is guaranteed to exist owing to the vector basis symmetry of phonons, which is a character distinct from electronic and other systems. In other words, this symmetry enforcement feature of the proposed nodal chain is limited to phononic systems. Interestingly, the chains in these five space groups exhibit two different patterns: for tetragonal systems, they are one-dimensional along the fourfold axis; for cubic systems, they form a threedimensional network structure. Based on first-principles calculations, we identify K2O as a realistic material hosting the proposed nodal-chain phonons. We show that the effect of LO-TO splitting helps to expose the nodal-chain phonons in a large frequency window. In addition, the nodal chains may lead to drumhead surface phonon modes on multiple surfaces of a sample. |
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VV01.00021: Thermal Signature of Majorana Fermion in a Josephson Junction Aabir Mukhopadhyay, Sourin Das Experimental attempts for the detection of Majorana bound state(MBS) are primarily based on two theoretical predictions: (1) 2e2/h resonant conductance peak at zero bias and (2) the 4π Josephson Effect, both of which rely heavily on the subgap physics of topological superconductors. In a complementary approach, we look for non-trivial signatures of MBS in heat transport across a Josephson Junction (JJ). Specifically, we consider a thermally biased JJ hosting a pair of MBS in a helical edge state of a2D topological insulator. We show that the presence of Majorana endstates in a three-terminal JJ setup results in two sets of testable relations(1): |
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VV01.00022: Controllable topological superconductivity in superconductor/ferromagnet heterostructures. Giorgos Livanas Majorana zero modes emerge at the defects of topological p-wave superconductors. However since p-wave superconductivity is scarce in nature several proposals have been put forward to engineer Majorana zero modes using conventional superconductors. Our group proposes a novel platform for topological superconductivity and Majorana zero modes comprising conventional superconductor (SC)/ ferromagnet (F) heterostructures. Our mechanism relies on the interplay of applied supercurrents (blue arrows) and weak magnetic fields (black arrows) emerging from the magnetic insulators (MI) in proximity with the conventional superconductors. We demonstrate that the coexistence of the supercurrent, the weak magnetic field and conventional superconductivity induces triplet p-wave correlations which mediate in the ferromagnet, whose magnetization is indicated by the white arrow, realizing an effectively spinless topological superconductor. We assert that the proposed superconductor/ferromagnet heterostructures exhibit enhanced controllability since topological superconductivity can be tuned apart from gate voltages applied on the superconductor or the ferromagnet, also by the applied supercurrents and the orientation of the magnetization of the magnetic insulators. |
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VV01.00023: Engineering Supersymmetric Potentials on the Edge of a Quantum Spin Hall System: Emergence of Volkov-Pankratov States and Construction of Reflectionless Potentials SUBHADEEP CHAKRABORTY, Vivekananda Adak, Krishanu Roychowdhury, Sourin Das Volkov-Pankratov (VP) states are a family of sub-gap states which appear at the smooth interface ( domain wall ) which separates two distinct gapped topological states of matter. We exploit known results from supersymmetry quantum mechanics to study the emergence of such states in the edge spectrum of the quantum spin Hall edge state when exposed to a smoothly varying mass term (Zeeman field) that switches sign at a given spatial point, thereby inducing band-inversion. Both the VP states at non-zero energy and the zero energy Jackiw-Rebbi mode stay localized at the interface, however the spin texture of the VP states turns out to be endowed with periodic windings in real space which is controllable with an electric field to which the Jackiw-Rebbi mode is insensitive. Moreover, the VP states exhibit an intriguing interplay between the electric and the magnetic field with a collapse of the entire spectrum when they are equal. Our theoretical predictions are confirmed with a BHZ model lattice simulation1. We further take a tan hyperbolic type mass term (which is experimentally more realizable) and show the existence of the in-gap bound states. This type of potential also has the interesting property of reflectionless transmission when certain conditions are met. Using this idea, one can engineer such potentials in the BHZ lattice model in a quantum transport simulation to study the above the gap transmission which is very close to unity. This may have a potential application to engineer a device with lossless transmission2. |
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VV01.00024: Symmetry-resolved entanglement of 2D symmetry-protected topological states Daniel Azses, David F Mross, Eran Sela Symmetry-resolved entanglement is a useful tool for characterizing symmetry-protected topological states. In two dimensions, their entanglement spectra are described by conformal field theories but the symmetry resolution is largely unexplored. However, addressing this problem numerically requires system sizes beyond the reach of exact diagonalization. Here, we develop tensor network methods that can access much larger systems and determine universal and nonuniversal features in their entanglement. Specifically, we construct one-dimensional matrix product operators that encapsulate all the entanglement data of two-dimensional symmetry-protected topological states. We first demonstrate our approach for the Levin-Gu model. Next, we use the cohomology formalism to deform the phase away from the fine-tuned point and track the evolution of its entanglement features and their symmetry resolution. The entanglement spectra are always described by the same conformal field theory. However, the levels undergo a spectral flow in accordance with an insertion of a many-body Aharonov-Bohm flux. |
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VV01.00025: A Pressure Dependent Comparative Study of Elastic, Electronic, Optical and Photocatalytic Properties of CsPbX3 (X= Cl, Br, I): A DFT Study for Optoelectronic Applications Mahbuba Aktary, Md Kamruzzaman, Rumana Afrose A systematic hydrostatic pressure dependence of the elastic, electronic, optical and photocatalytic properties of CsPbX3 (X = C, Br and I) has been evaluated based on ab initio simulations. This study reveals that the mechanical stability sustain up to 25 GPa for Cl and I contained perovskites but Br contain sustains stability up to 75 GPa. It is also found that the mechanical properties of CsPbX3 perovskites are ductile under ambient conditions and their ductility has been significantly improved (decreases) with pressure. The electronic properties suggested that CsPbX3 perovskites have a direct energy band gap that decreases with increasing applied pressure due to structural change. The band gap becomes zero at 20, 15 and 10 GPa which insights the transportation of crystal structure. Absorption peak of CsPbX3 perovskites is radically changed toward the lower photon energy region with the applied pressure. The photoconductivity, reflectivity, and dielectric constant have an increasing tendency under pressure. CsPbI3 is the best photocatalyst for hydrogen evolution reaction and CsPbBr3 is the most stable photocatalyst due to its nearly balanced oxidation and reduction potentials, but CaPbCl3 is better for O2 production. These findings would be beneficial for experimental study and suggest that pressure has a significant role on the physical properties of CsPbX3 perovskites that might be promising for optoelectronic, photonic and hydrogen production along with biodegradation of polluted and waste materials. |
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VV01.00026: Twist Induced Tunability of Electronic and Optical Properties in a Van der Waal Janus Heterostructure Subhasmita Kar, Puja Kumari, Soumya J Ray Tremendous research attention is currently in focus onto two-dimensional (2D) nano-materials and their heterostructure due to their rich physical properties and diverse technological applications [1, 2, 3]. Recent discoveries of 2D Janus materials with broken symmetry have shown promising potential for the current semiconductor industry due to their distinctive physical and chemical characteristics (strong Rashba effect, out-of-plane piezoelectric polarisation) [4, 5]. The 2D van der Waals heterostructures (vdWH) are smart artificial materials composed of two similar or different types of monolayers [6]. We have systematically studied the stability, electronic, and optical properties of nine different Janus vdWHs (MoS2/MoSeTe, MoS2/WSeTe, WS2/MoSeTe, WS2/WSeTe, MoSe2/MoSeTe, MoSe2/WSeTe, WSe2/MoSeTe, WSe2/WSeTe, and MoSeTe/WSeTe) through first-principles based calculations. Our results show that when TMD monolayers are stacked vertically with Janus monolayers, an intrinsic electric field appears because of the lack of mirror symmetry and charge accumulation, which leads to the origin of versatile properties in Janus vdWHs. In addition, the interlayer twist also induces an electronic phase crossover from indirect to direct bandgap semiconducting state at some specific rotation angles. |
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VV01.00027: Van der Waals twistronics in a MoS2/WS2 heterostructure Shubham Sahoo, Saurav Sachin, Shivani Rani, Puja Kumari, Subhasmita Kar, Soumya J Ray Twisted Van der Waals heterostructure made of two or more two-dimensional (2D) materials [1,2] has recently gained lot of interest due to the recent exploration of various strong-electron correlation effects. Here, we studied the heterostructure of MoS2/WS2 at different twist angles to look for exciting electronic coupling effects between the individual constituents. In this work, first-principles based density functional theory calculations [3] were used to explore the structural, electronic, mechanical and optical properties of the heterostructure at different twist angles, chosen at the minimum strain configurations. The interlayer twisting induces structural phase transition from orthorhombic => hexagonal => monoclinic symmetry. The semiconducting nature of the heterostructure changes from direct to indirect bandgap semiconductor state at different twist angles. The maximum value of optical conductivity is found to be 2000 AV-1cm-1 at a twist angle of 21.79º. Our investigation showed a variation in the optical band gap value from 1.1 eV to 1.4 eV under different twisted angles. The effective mass of the electrons has a rapid variation as twist angle changes. With changing twist angle, the Poisson's ratio and shear modulus shift from 0.16 to 0.21 and 25.6 GPa to 32.1 GPa, respectively. Young's modulus and shear modulus are found to be maximum at 43.9º angle among all the twisting angles. Also this system showed good absorption in the visible region, which can be an interesting candidate for optoelectronic applications. |
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VV01.00028: Graphene enabled practical Molecular Electronics BHARTENDU PAPNAI, Mario Hofmann The idea of producing functional elements on atomic length scales has become a recent focus of our research since the scaling of conventional electronics is reaching the molecular domain.The concept to build a device within a molecular scale by exploring the properties of 2D material Graphene. |
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VV01.00029: SUPERCONDUCTIVITY | MAGNETISM . |
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VV01.00030: The study of transport and magnetic properties of FeTe0.60Se0.40 single crystals grown by the self-flux method. Shivam K Miglani, HIMANSHU CHAUHAN, Ghanshyam D Varma Iron chalcogenide (FeCh) superconductors have become one of the most investigated superconducting materials because of their good crystalline symmetry, complex electronic and magnetic phase diagrams. They provide a platform for studying correlated quantum matter. Recently topological superconductivity has been discovered in FeCh superconductors. But to support the existence of topological surface states, electrical transport investigations are required. In this approach, we have studied structural, transport, and magnetic properties of synthesized FeTe0.60Se0.40 single crystals grown by self-flux method. The structural properties show the pure tetragonal phase of the grown single crystal and alignment of the layer in c-axis. Transport and magnetic studies demonstrate the anisotropy in the grown single crystal and confirm the transition temperature Tc~14 K. Moreover, linear magnetoresistance at 16 K in the high field region has been observed for field H || c but not detected in the direction H || ab, indicating the presence of topological surface states. Our work will be useful in developing FeCh superconductors with good superconducting properties, and the intrinsic topological superconductivity is relevant for implementing quantum computing devices. |
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VV01.00031: Is spontaneous vortex generation in superconducting 4Hb-TaS2 from vison-vortex nucleation with ℤ2 topological order? Gang Chen
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VV01.00032: Realization of spin torque majority gate logic operation with current induced domain wall motion Dongryul Kim, Chun-Yeol You, June-Seo Kim, Jaehun Cho, Soobeom Lee, Seong Bok Kim, Jun-Su Kim Recently, a study to reduce the power consumption required for artificial neural network (ANN) system calculating is being actively discussed. Due to the bottleneck phenomena or inefficient data transfer method, conventional Von Neumann architecture is improper for the role of the logic calculation of the ANN system. As one of the substitutes, the spin torque majority gate (STMG) is paid attention to for developing logic devices with ultralow power consumption. |
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VV01.00033: Stimuli controlled electronic and magnetic properties of two-dimensional (2D) magnetic Janus materials Saurav Kumar, Subhasmita Kar, Soumya J Ray Magnetic van der Waals nanocrystals with intrinsic magnetic anisotropy provide an ideal platform for exploring magnetism in the low-dimensional limit [1,2]. In the post-graphene era, the discovery of magnetism in two-dimensional (2D) intrinsic nanomagnets has opened up exciting possibilities for low-dimensional spintronics [3,4,5]. In this work, we investigated three new 2D Janus nanomagnets VBrCl2, VBrI2, and VClBrI for the first time. First-principles-based density functional theory calculations reveal that these monolayers are intrinsically magnetic with indirect band gap semiconducting properties and further the magnetic and electronic properties of these monolayers are enhanced with the application of biaxial strain and electric field. We observe interesting electronic and magnetic phase transitions, tunable band gap, and supreme enhancement of the Curie temperature (∼ 686%). Large magnetic anisotropic energy (MAE) with a high magnetic moment and tunable band gap properties make these Janus materials useful candidates for future information storage, optoelectronics, and 2D spin circuit applications. |
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VV01.00034: Microwave-synthesis of Two-Dimensional Metal Oxychloride Using Metal Chloride Precursor: Experimental and Thoretical Study Towhidur Rahaman, SHANTANU MAJUMDER, Soumya J Ray The existence of intrinsic ferromagnetism in Two-dimensional (2D) materials has invited numerous opportunities for applications in spintronics, memory devices, and data storage [1,2]. Among them, 2D van der Waals magnetic insulators at nanoscale level has received significant attention for their electronic, magneto-electronic and magneto-optical properties. Microwave synthesis is an extremely promising technique for the scalable synthesis of the 2D metal oxides and oxychlorides in a reproducible manner. Metal Chloride precursor CrCl3.6H2O was dispersed in a suitable solvent like dimethylformamide (DMF) or even direct microwave heating can immediately convert to the corresponding metal oxychloride 2D sheets of CrOCl due to the partial elimination of chlorine. Morphology and crystallographic structure are confirmed by the Scanning electron microscopy (SEM), High resolution transmission electron microscopy (HRTEM) and X-Ray Diffraction (XRD). We use energy dispersive spectroscopy (EDS) to examine the atomic ratio for Cr, O and Cl of 1:1:1. The experimental results have been complementd with density functional theory calculations to explore the spin-specific electronic, magnetic and transport properties of the system under different stimuli [3]. The material is found to be semiconducting and offering rapid enhancement of the critical temperature in the presence of strain [4]. This ferromagnetic semiconducting phase of CrOCl can have great significance in designing 2D spintronic devices and sensors. |
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VV01.00035: Proximity induced exchange coupling in a Phosphorene heterojunction with CrI3 substrate: a first-principles calculation Puja Kumari, Soumya J Ray The two-dimensional (2D) van der Waals (vdW) materials offer a platform to design heterojunctions in various stacking orders to create different functionalities at an atomically thin thickness [1]. Recently, the family of 2D ferromagnetic materials [2, 3, 4] has emerged as a new field of research, which violates the Mermin-Wagner theorem, and their exciting electron charge and spin behavior offer potential for spin devices. In this study, we have systematically investigated the electronic and magnetic behavior of phosphorene - CrI3 (P/CrI3) heterojunction through the first-principles based density functional theory (DFT) calculations. We built the heterojunction by using a single layer of black phosphorene with magnetic substrate 2D CrI3 by weak vdW force, where the average relaxed interlayer distance is 3.51Å [5]. The result indicates that the valence and conduction bands near the Fermi level are localized in different monolayers of P/CrI3 heterojunction, where the energy gap of heterojunction is reduced from that of the monolayers of black phosphorene and CrI3. The intrinsically nonmagnetic phosphorene layer [6] is also magnetized and enhances the magnetic anisotropy energy of the CrI3 substrate in heterojunction. In addition, we demonstrate perfect spin filtering by spin injection from a ferromagnetic substrate to a phosphorene layer. These results help in a fundamental understanding of the 2D heterojunctions and are of significant importance for CrI3-based spintronic devices. |
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VV01.00036: Magnetic skyrmion diode based on symmetry breaking of potential energy barriers Hee-Sung Han, Dae-Han Jung, Namkyu Kim, Ganghwi Kim, Suyeong Jeong, Sooseok Lee, Mi-Young Im, Ki-Suk Lee Magnetic skyrmion are topologically nontrivial spin structures that can be stabilized on a ferromagnetic background with the Dzyaloshinskii-Moriya interaction. They represent the ultimate small achievable size for nonvolatile magnetic memory elements and can be driven by low-density spin-polarized currents. Thus, they are being proposed as information carriers for a new generation of ultra-dense magnetic memories and logic devices. For skymion-based potential applications, we present a skyrmion diode operated by a unidirectional skyrmion transport, which has recently been realized by us. We manipulate the skyrmion transport by engineering asymmetric shapes of geometric structures. Furthermore, we develop a simple method to describe the underlying mechanism behind the unidirectional skyrmion transport by characterizing the topography of potential energy surfaces from a purely geometric perspective. Our approach enables a deeper physical insight into skyrmion transport manipulation and efficient design of skyrmion-based devices in geometric structures. |
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VV01.00037: STRONGLY CORRELATED SYSTEMS, INCLUDING QUANTUM FLUIDS AND SOLIDS | COMPLEX STRUCTURED MATERIALS, INCLUDING GRAPHENE | SUPERLATTICES, AND OTHER ARTIFICALLY STRUCTURED MATERIALS | SURFACES, INTERFACES, AND THIN FILMS . |
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VV01.00038: Title: Light-induced band-topology & metal-insulator transitions in interacting Kagome lattice SUBHAJYOTI PAL Abstract: |
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VV01.00039: Anomalous Enhancement in Tunneling density of states in a Luttinger liquid : interplay of nonlocal interactions and proximitized superconductivity. Amulya Ratnakar Suppression of local single-electron tunneling density of states (TDOS) in zero bias limit is the hallmark property of Luttinger liquids (LLs) and is due to the fact that there are no electronlike quasiparticles in the low-energy excitation spectrum of LL. An exception to this suppression, leading to enhancement in TDOS, is possible if we have Andreev-reflection (AR) like process at the junction. This can be achieved for a LL in proximity to a superconductor (SC) or due to strong correlations localized at the junction of multiple LLs which can drive the system to a fixed point. All such junction fixed point hosting AR-like process were found to be unstable against relevant perturbations in the RG sense. We report the possibility of having TDOS enhancement along with stable fixed point, for a much simpler junction of two LLs in the presence of non-local interactions. We consider a LL junction with current conserving normal (N) boundary condition (BC) and current non-conserving Superconducting (SC) BC. We establish symmetry relation between the normal and superconducting sectors of the theory. Such a model can be realized on the edge states of a bilayer quantum Hall (QH) system with tunnel (SC pair) coupling such that intralayer and interlayer interactions mimics the local and nonlocal interactions. This study is inspired by the current experimental advances where Large cross Andreev reflection has already been observed for a fractional QH edge in proximity to a superconductor. |
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VV01.00040: Many-body localization transition in a frustrated XY chain Murod Bahovadinov We show evidence of many-body localization (MBL) transition in a one-dimensional isotropic XY chain with a weak next-nearest-neighbor frustration in a random magnetic field. We perform finite-size exact diagonalization calculations of level-spacing statistics and fractal dimensions to characterize the MBL transition with increasing the random field amplitude. An equivalent representation of the model in terms of spinless fermions explains the presence of the delocalized phase by the appearance of an effective nonlocal interaction between the fermions. This interaction appears due to frustration provided by the next-nearest-neighbor hopping. |
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VV01.00041: Finite-bias first-principles calculations of contact resistance of transition metal dichalcogenides Tae Hyung Kim, Juho Lee, Yong-Hoon Kim Despite the tremendous amount of experimental and theoretical efforts to achieve the low contact resistance between metal electrodes and transition metal dichalcogenide (TMDC) semiconductors, a critical issue in developing TMDC-based electronic and optoelectronic devices, the atomic-scale understanding of metal-TMDC interfaces is still incomplete. In this study, adopting the junction models based on the Ag/MoS2 top- and edge-contact models, we perform equilibrium density functional theory (DFT) and finite-bias multi-space DFT calculations [1,2] and extract contact resistance values at different TMDC channel lengths. From finite-bias calculations, we identify the transitions in the contact resistance scaling with the increase of the channel length and find that they result from the transition from the regime where Ag metal-induced gap states dominate the charge injection to that where the conduction band edge states of the MoS2 channel contribute to the charge transport. Such transition behavior cannot be observed, indicating a critical missing ingredient of the previous first-principles studies of TMDC contact resistance. Quantitatively, the finite-bias contact resistance value of the Ag/MoS2 top contact is found to be lower than that of the Ag/MoS2 edge contact. However, considering the Ag/WSe2 top- and Ag-WSe2 edge-contact models, we obtain an opposite conclusion, which indicates that the optimal contact geometry for TMDCs can be different depending on the metal-TMDC material combination. This work clarifies many contradicting conclusions in the literature and provides theoretical guidelines for designing low-resistance metal-TMDC contact. |
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VV01.00042: Harmonic Scattering of Nonlinear Waves from Layered Materials that mimics Additively Manufactured Metals Pravinkumar R Ghodake Recent developments in additively manufactured materials show its capabilities towards designing single and multi-material layered metallic structured materials. Additively manufactured structures perform efficiently towards the targeted performance at the macro-scale level. However, their structural health monitoring using nonlinear ultrasonic techniques becomes challenging and complex due to multiple layers deposited during additive manufacturing and the various microscale damages such as micro-voids, micro-cracks, accumulation of local plasticity at the interfaces, etc. In this study, various numerical experiments are conducted using the finite element method to gain insight into the interaction of nonlinear elastic waves with such additively manufactured metallic materials. The presence of backscattered harmonic waves along with the forward scattered waves and their properties is demonstrated through studies such as the interaction of monochromatic waves, one-way two-wave mixing, and two-way two-wave mixing. Similarly, the harmonic scattering of waves from an additively manufactured bi-metallic material is demonstrated and discussed in detail. The interplay between linear and nonlinear impedance-mismatch leads to interesting forward and backscattered wave responses. Amplitudes of backscattered waves are nearly equal to the forward scattered waves in some case studies. |
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VV01.00043: Resistive switching in a Bio-Resistive Random-Access Memory device (Bio-ReRAM) Dimpal Kumari, Soumya J Ray Resistive Random Access Memory (ReRAM) is considered as one of the prominent emerging memory technologies having enhanced storage density, high speed, high scalability, long endurance and low power operation with CMOS compatibility [1,2,3]. Organic biomaterials like pectin, sericin, starch, egg albumen, chitosan etc. are potential elements for environmentally benign, biocompatible, non-toxic, transient, transferable and biodegradable electronic memory devices which uses resistive switching mechanism for information storage and required medical implants. Here, we highlighted the process of extracting and exploiting a biomaterial Aloe vera Gel to fabricate a distinctive type of bio-electronic memory device. This memory cell comprises of a simple MIM structure, in which a thin nanolayer of Aloe vera Gel is sandwiched between an Ag top and ITO bottom electrode. FTIR and UV- Visible spectroscopy have been done to investigate the presence of polymers, bonds, functional groups, constituents for the confirmation of purity and transparency and insulating behavior respectively. The Bipolar resistive switching behavior is observed due to electrochemical growth and dissolution of Ag metallic filaments between top and bottom electrodes over a large number of switching cycles. The behavior of current-voltage curve for SET and RESET state is confirmed by fitting the curve, which gives the desired value of slopes. Detailed analysis revealed that the memory device based on Aloe vera Gel thin film is very robust and reliable because of its high on/off ratio, long retention time and endurance up to 100 cycles. Thus, such biomaterials can provide a promising platform for the sustainable development of green electronics and construct the way towards next generation memory applications. |
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VV01.00044: Temperature dependent resistive switching behavior of a pectin based heterostructure Arpita Roy, Soumya J Ray Organic material-based optoelectronic and electronic devices have recently received a lot of attention due to their simple device structure, preferred scalability, low cost, low power consumption etc. Resistive random-access memory (RRAM) works on the principle of resistive switching which has potential for application in memory storage and neuromorphic computing [1, 2, 3]. Here, natural orange peel was used to extract biocompatible pectin to design a resistive switching memory device of the structure Ag/Pectin/Indium tin oxide (ITO) and studied a behaviour between a temperature range of 50K and 300K. The basic principle of Resistive Switching behaviour is based on the formation of a conductive filament. While applying voltage, Ag is broken down by Ag+ ions and at higher temperature Ag ions have enough energy to break out of their lattice sites and move easily towards bottom electrode. But at low temperature, due to lack of sufficient energy, Ag+ ions cannot freely move inside the sample to form a conductive filament-like structure. The microscopic characterisation releaved the texture of the surface and thickness of the layers. From FTIR spectra, we confirmed the presence of C–OH, COOH, OH bonds in pectin. The current-voltage characteristics done over 100 cycles of repeated cycling revealed sustainable resistive switching behaviour with appropriate ON/OFF ratio from endurance plot. The robust switching characteristics suggested the possible use of such devices for bioelectronic memory applications. |
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VV01.00045: Enhanced Catalytic Dehydrogenation of Methylcyclohexane over Colloidal Pt-Decorated Functionalized Graphene Sheets as Fuel Additives SUJIN KIM, Sungwook Hong, Chang-Min Yoon, Hyung Ju Lee, Hyung Sub Sim This study explores the reaction mechanisms of hydrocarbon loaded with colloidal Pt-decorated functionalized graphene sheets (Pt@FGS) using high-pressure liquid flow reactor experiment and the reactive force-field (ReaxFF) molecular dynamics (MD) simulation. Previous work [Sim et al. Combustion and Flame, 217, 212-221, 2020] on the supercritical fuel decomposition of methylcyclohexane (MCH) loaded only with FGS showed that there is a slight enhancement in fuel conversion rate due to the interactions between oxygen-containing functional groups onto the FGS surface and fuel molecules. In this study, we present a remarkable improvement in the fuel decomposition and hydrogen formation of MCH resulting from the enhanced catalytic dehydrogenation by the suspension of Pt@FGS at a very low loading concentration. From high-pressure and high-temperature experiments, it was found that the bicomposite structure of Pt@FGS at the loading concentration of 50 ppmw served to lower the reaction energy and energy barrier for dehydrogenation, which could result in the enhanced conversion rates and increased reactive product yields such as hydrogen and low-carbon number species. Subsequent molecular dynamics studies provide evidence that the Pt nanoparticles attached to the FGS significantly catalyze the dehydrogenation of methylcyclohexane into intermediate C7H13 radical. Interestingly, when the presence of Pt@FGS in the fuel even at the very low concentration, the hydrogen yield is increased. |
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VV01.00046: Modulating the magneto-transport properties of epitaxial SrRuO3 (111) thin films by controlling the defects Santosh K Khetan, Shwetha G Bhat, Pranav P Pradeep, Debakanta Samal, P S Anil Kumar (111) oriented perovskite transition metal-oxide is believed to host topological states due to their buckled honeycomb lattice structure1. Further, SrRuO3 (SRO) films along (111) are predicted to have emergent phases such as Haldane’s quantum Hall state even without the presence of any magnetic field2. In this regard, we have grown high-quality epitaxial SRO thin films using the RHEED-assisted PLD on atomically terminated SrTiO3 (111). These films are characterized using XRD, magnetic, and magnetoresistance (MR) /Hall transport studies. |
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VV01.00047: Electronic structure of monolayer TiTe2 thin films studied by high-resolution ARPES Koki Yanagizawa, Tappei Kawakami, Ken Yaegashi, Katsuaki Sugawara, Takashi Takahashi, Takafumi Sato Atomically-thin transition-metal dichalcogenides (TMDs) have attracted much attention since they show exotic quantum phenomena associated with two-dimensionalities, such as unconventional charge-density waves (CDW) and Ising superconductivity. Among TMDs, 1T-TiTe2 with the octahedral structure has been a target of intensive studies since monolayer 1T-TiTe2 undergoes CDW transition with (2×2) periodicity, while CDW vanishes in bilayer or thicker films. To elucidate the origin and the layer dependence of CDW transition, we have fabricated monolayer TiTe2 on bilayer graphene by molecular-beam-epitaxy method and studied their electronic states by micro-focused angle-resolved photoemission spectroscopy. We clearly observed the semi-metallic nature and CDW-induced band folding in monolayer 1T-TiTe2. In this talk, we will discuss the possibility of controlling the CDW phase transition by precisely tuning the carrier concentration. |
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VV01.00048: QUANTUM INFORMATION, CONCEPTS, AND COMPUTATION | INSTRUMENTATION AND MEASUREMENTS | ENERGY RESEARCH AND APPLICATIONS | APPLICATIONS (IT, MEDICAL/BIO, PHOTONICS, ETC.) | DATA SCIENCE | EARLY CAREER SCIENTISTS . |
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VV01.00049: Full tunability and quantum coherent dynamics of a driven multilevel system Yuan Zhou The tunability of a quantum system is crucial to its capacity in quantum computing, though it always poses significant demand on the design and fabrication of a device. Here, we demonstrate that Floquet engineering based on a longitudinal drive provides possibilities for enhancing the tunability of a quantum system without additional resources. In particular, we study a driven singlet-triplet (ST) system in a gate-defined quantum dot system and derive the effective Hamiltonian which captures the dynamics well. Notably, the engineered Hamiltonian reveals a full tunability controlled by the microwave field. Such tunability yields several featured phenomena as we would like to discuss, such as the odd-even effect, engineered coherent population trapping (CPT), and adiabatic state transfer based on amplitude modulation. We demonstrate the odd-even effect and engineered CPT based on an ST system in a double-quantum-dot system. With no surprise, the experimental phenomena agree well with the effective Hamiltonian, which indicates the nontrivial tunability enabled by the driving field. |
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VV01.00050: Effective Hamiltonian for Cross-Cross Resonance gate and Frequency tuning in Transmon qubits Kyungsun Moon, yousung kang Two-qubit entangler is one of the most important components for quantum computer. For a quantum computer based on transmon qubit, the Cross-Cross Resonance(CCR) gate has been recently proposed, which seems to operate faster than Cross-Resonance(CR) gate as an iSWAP gate. However, unlike the CR gate, the CCR gate needs a frequency change induced by Stark shift. Here, we present the theoretical study of CCR gate in transmon qubits. Using the Schrieffer–Wolff transformation and rotating-wave approximation, we obtain both the effective Hamiltonian for CCR gate and the frequency condition of CCR gate. We also perform numerical simulation using Quantum Toolbox in Python(QuTip). Our numerical simulation result shows an excellent agreement with the analytical one. |
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VV01.00051: A Few Studies based on Circuit QED system with Triple-Leg Stripline Resonator Kyungsun Moon, Dongmin Kim We have theoretically proposed a new circuit QED system implemented with a triple-leg stripline resonator (TSR). Unlikely from the LSR, the fundamental intra-cavity microwave modes of the TSR are two-fold degenerate. When a superconducting qubit is placed near one of the TSR legs, one fundamental mode is directly coupled to the qubit, while the other one remains uncoupled. Using our circuit QED system, we have theoretically studied a two-qubit quantum gate operation in a hybrid qubit composed of a flying microwave qubit and a superconducting qubit. |
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VV01.00052: A Hybrid Quantum-Classical Molecular Force Calculator (VQE-F) Integrated with Atomic Simulation Environment (ASE) for Molecular Geometry Optimization Shampa Sarkar, M R Nirmal, Manoj Nambiar, Sriram G Srinivasan To trace accurately the chemical reaction pathway of molecules, one requires accurate determination of the equilibrium or lowest energy molecular geometry, by computing energy gradients with respect to molecule’s nuclear coordinates or perturbatively distort the nuclear configuration to find the minimum energy configuration. In this work, we present a modular quantum-classical hybrid framework for molecular geometry optimization. We report here for the first-time an interface for the Variational Quantum Eigensolver (VQE) based Energy (VQE-E) and Force (VQE-F) calculation, to the classical computational Atomic Simulation Environment (ASE). ASE is a widely used open-source suite of Python modules for ab-initio atomistic simulation towards molecular geometry optimization and molecular dynamics. We used a finite-difference based, nested numerical differentiation technique to compute the atomic forces where the energy is obtained from the VQE algorithm. The working of this hybrid quantum-classical interface is demonstrated by optimizing the geometry of water molecule in different molecular orbital basis sets, which demonstrated a trade-off between computational accuracy and quantum circuit complexity. The calculator can further be configured to select different active space transformations, trial state ansatzes, fermion to qubit mappings and classical optimizers in the VQE workflow, for efficient and accurate estimates of molecular geometry. |
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VV01.00053: Federated Learning with Quantum Secure Aggregation Yichi L Zhang
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VV01.00054: Neural ray tracing for a neutron triple axis spectrometer Anton P Stampfl The behaviour of a neutron scattering instrument may be approached both analytically as well as numerically. Traditionally numerical studies entail some form of ray-tracing approach that allows for a realistic and accurate model of the behaviour of an instrument. In-particular resolution and flux are two important parameters that require accurate determination when building an instrument like a triple-axis. The numerical approach produces realistic results albeit often using a skeleton type model of the instrument. Despite the success of a triple-axis configuration where radiation is conditioned in reciprocal and energy space, background signal observed in all spectra measured, is a very important parameter that isn’t easily quantifiable without including the structural and shielding materials that also go into a full working spectrometer. |
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VV01.00055: Ultralow thermal conductivity and thermoelectric performance of two-dimensional KCuX (X=S, Se) materials for energy harvesting Neelam Gupta, Shubham Kumar, Shivani Rani, Soumya J Ray, Puja Kumari Two - dimensional (2D) materials have attracted considerable attention recently due to their outstanding electronic, optical, magnetic, and transport properties which can be widely used in electronic, optoelectronics, spintronic, sensing, energy storage (e.g. batteries and supercapacitors) and energy conversion devices (e.g., thermoelectric, and solar cells) [1,2]. The 2D materials possess excellent electrical and mechanical properties, which are suitable to fabricate high-performance composite thermoelectric materials as well [3]. In this work, we studied thermoelectric properties of KCuS and KCuSe monolayers which belong to a 2D ternary quintuple layer family named PQR (P = K, Na, and Rb), (Q =Cu, Au, and Ag), and (R = S, Se, and Te). Using First-principles based density functional theory (DFT) calculations and Boltzmann transport equation (BTE), we have calculated the thermoelectric (TE) properties of KCuX (X = S, Se). The result indicates that KCuS and KCuSe possess a direct band gap of 0.193 eV and 0.211 eV respectively. The obtained ultralow value of lattice thermal conductivity of 0.015 Wm−1K−1 for KCuS, and 0.006 Wm−1K−1 for KCuSe indicates towards large value of the figure of merit (ZT). We have estimated the values of various TE parameters like the Seebeck coefficient, electronic transport properties, power factor, and ZT at various temperatures. These combination of TE properties indicates towards potential use of KCuX (X=S, Se) family of materials for energy harvesting applications. |
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VV01.00056: Machine learning-driven smart web app interface for effective urine pH detection using polyaniline functionalized paper sensor Souvik Biswas, Arijit Pal, Koel Chaudhury, Soumen Das A paper-based disposable impedimetric pH sensor has been developed to measure urine pH. In situ polymerization of aniline over paper substrate by chemical oxidative method is utilized to fabricate the sensing device. The acidic pH of the analyte solution maintains the emeraldine salt form of polyaniline, while the alkaline pH converts the emeraldine salt into emeraldine base. This sensing principle is employed to detect the urine pH with a sensitivity of 1.6 kΩ/pH for acidic region and 6.2 kΩ/pH for alkaline region, at a frequency of 1kHz. The sensing mechanism is also verified by employing a density functional theory-based first principle calculation. The formation of emeraldine salt and emeraldine base at acidic and alkaline pH can be validated by experimental Raman spectra. The observed spectra corroborate with the theoretical Raman spectra computed from the first principle calculations. The structural changes after exposure to acidic and alkaline solutions were experimentally verified by impedance spectroscopic method and correlated with the theoretical energy band gap study using density functional theory. Furthermore, the impedimetric responses were used to develop a machine learning-based smart and interactive web application, which predicts urine pH with an average accuracy of 98%. |
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VV01.00057: Jamming-controlled shear stiffening in particle-filled soft solids Yiqiu Zhao, Haitao HU, Qin Xu Dispersing hard particles into a soft polymer gel forms a soft composite that is widely used in mechanical and biomedical applications. The global mechanics of such composites is strongly affected by the collective interactions among the embedded particles. Predicting the nonlinear mechanical features of such materials presents a great challenge. To address the problem, we performed a systematic experimental study on a model system consisting of micron-sized polystyrene spheres randomly dispersed in a crosslinked polydimethylsiloxane (PDMS) matrix. We found that the shear modulus of densely filled samples grows significantly, in some cases more than ten-fold, under small deformations. Inspired by the stress-controlled shear-thickening effects in dense suspensions, we proposed a phenomenological model that explains the stiffening effect through critical scaling laws near a stress-dependent jamming point. The model not only captured our observations but also predicted the emergence of mechanical instability for extremely dense samples. Our work provides the experimental evidence to support that jamming criticality controls the responses of soft composites, and revealed a similar role played by the particle contact networks in determining both the elasticity of dense particle-filled soft solids and the rheology of dense granular suspension. |
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VV01.00058: Wednesday Poster Miscellaneous I . |
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VV01.00059: Effect of Jahn-Teller distortion on the magnetic characteristics of orthorhombic YMnO3 thin films MY NGOC DUONG, Yu-Xun Chen, Tahta Amrillah, Song Yang, Chen-En Liu, Shu-Chih Haw, Chia-Hung Hsu, Jin-Ming Chen, Kaung-Hsiung Wu, Chang-Yang Kuo, Jenh-Yih Juang The local strain on the MnO6 octahedra in perovskite multiferroic manganite has been found to impose various intriguing effects on orbital and magnetic ordering texture, which is the key to the magnetoelectric coupling giving rise to the eventual multiferroicity. In this study, we deliberately grew the orthorhombic YMnO3 (o-YMO) thin films on SrTiO3(100) and SrTiO3(110) single crystal substrates by pulsed laser deposition (PLD) to manipulate the lattice strain along specific crystallographic orientations. The crystal structure and relevant lattice strain of the thin films were characterized by X-ray scattering, including θ-2θ and Φ-scans, and reciprocal space mapping (RSM). Moreover, the measured Mn L2,3-edge X-ray absorption spectroscopy (XAS) spectra were rigorously compared with the theoretically calculated ones, which evidently exhibited two distinctly different orbital ordering textures for o-YMO films grown on different SrTiO3 substrates. The shift of Mn d-orbital degeneracy is expected to result in significant effect on the magnetic properties of the thin films. Indeed, the temperature dependent susceptibility χ(T) showed evidence of coexistence of the E-type and cycloidal antiferromagnetic ordering in the temperature range of 30-40 K in both films with, nevertheless, very different and complicated associated M-H hysteresis loops, which were also very much dependent on the direction of the applied field with respect to crystallographic orientations. |
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VV01.00060: A highly effcient thermionic cathode for thermionic emission and energy conversion Feng Jin We have developed a highly efficient thermionic cathode that exhibits both strong thermionic emission and thermionic energy conversion (cooling). The cathode consists a triple coiled tungsten filament as its base and the barium strontium oxide coated carbon nanotubes (CNTs) as its emitters. The cathode produces a strong thermionic emission of around 3 A/cm2 at 1400 K. It operates at a much lower cathode fall voltage in a low-pressure Ar plasma, confirming its high efficiency in electron emission. The cathode also exhibits high efficiency in thermionic energy conversion, a large thermionic cooling effect of the emitting cathode surface was observed as a result hot electron emission. Details of the cathode structure and its fabrication process will be presented, along with the measurement results on thermionic emission, cathode fall in plasma environment and thermionic cooling of the emitting surface. |
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VV01.00061: Cluster glass vs. Multiferroic state in MnSb2Se4 Rahul Kumar In the last few decades, the quaternary and ternary transition-metal chalcogenides, having low crystal symmetry, have become a rich playground for independently organized investigations of magnetic exchange and electronic transport interactions in magnetic semiconductors. Among the known quaternary transition-metal chalcogenides, the transition-metal chalcogenide family AB2X4; (A = Fe, Mn; B = Sb, Bi, and X = S, Se) exhibits diverse crystal structures, where the A-site cation connectivity ranges from 1 to 3 D, depending on B-site cations, and anions. Among these compounds, MnSb2Se4 crystallizes in a monoclinic space group C2/m and orders antiferromagnetically below TN = 22.5 K. In addition, careful analysis of the x-ray diffraction revealed the presence of antisite disorder (∼ 19 %) between Mn and Sb sites. As we know, antisite disorder can be a significant parameter in determining the ground state of a magnetic material. In this talk, I’ll be talking about the impact of antisite disorder on the magnetic ground state of MnSb2Se4. |
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VV01.00062: Reservoir crowding in a far-from-equilibrium exclusion process with dynamic defects Nikhil Bhatia, Arvind K Gupta The transport phenomena frequently happen in many systems at all scales; be it the micro level such as the intracellular transport in biological systems or the macro level which includes vehicular traffic, pedestrian flow, etc. These physical systems exhibit complex behavior and violate the law of detailed balance under a stationary state. These processes are classified as driven-diffusive systems, driven by some external field or self-driven, and eventually reveal a non-equilibrium steady state having a distinctive non-zero current. In the last few decades, the totally asymmetrically simple exclusion process (TASEP) is found to be a classical model that provides a unified framework to analyze the collective properties of these stochastic transport problems. TASEP is a 1D lattice comprised of particles that hop stochastically and uni-directionally along the linear track following the hard-core exclusion principle. |
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