Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session Y01: Quantum DynamicsRecordings Available
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Chair: Zhurun Ji, University of Pennsylvania Room: McCormick Place W-175A |
Friday, March 18, 2022 8:00AM - 8:12AM |
Y01.00001: Quantum Scrambling in Molecules . Chenghao Zhang, Martin Gruebele, Peter G Wolynes In quantum systems, out of time order correlators (OTOCs) can be used to probe the sensitivity of the dynamics to perturbing the Hamiltonian or changing the initial conditions ordinarily associated with classical chaos or its quantum analog. The vibrations of polyatomic molecules are known to undergo a transition from regular dynamics at low energy to facile energy flow at sufficiently high energy. Molecules therefore represent ideal quantum systems to study the transition to chaos in many-body systems of moderate size (here 6 to 36 degrees of freedom). By computing quantum OTOCs and their classical counterparts we quantify how information becomes ‘scrambled’ quantum mechanically in molecular systems. |
Friday, March 18, 2022 8:12AM - 8:24AM |
Y01.00002: Generation of entangled photon pair from biexciton cascade decay in quantum dots Arindam Chakraborty, Nicole Spanedda This work presents a theoretical and computational investigation of biexcitonic decay processes in GaAs QDs for the generation of entangled photon pairs (EPP). Entangled photon pairs (EPP) are important in quantum optics and essential for quantum information, quantum teleportation, quantum key distribution, and controlled logic operations. Semiconductor quantum dots (QD) are especially well suited for the generation of EPP and have been proven to have high-entanglement fidelity, extraction efficiency, and photon indistinguishability. QDs have been shown to be good candidates for entangled photon generation. We have used the electron-hole multicomponent coupled-cluster theory (eh-mcCC) for treating the excitonic and biexcitonic states. We have included light-matter interaction in the eh-mcCC method using the dressed-atom approach and the time-propagation is performed diagrammatically. The inclusion of spin states and spin-orbit coupling is crucial for EPP generation and was included in the eh-mcCC formulation using the spin-orbit relativistic effective potential (SOREP) method. The developed method was applied on a series of GaAs QDs and discussions exciton binding energies, biexciton binding energies, fine-structure splitting, and photon-entanglement characteristics will be presented. The results from this study demonstrate size-effect and chemical design parameters needed for the generation of highly-entangled photons from quantum dots. |
Friday, March 18, 2022 8:24AM - 8:36AM |
Y01.00003: Statistical Correlation Between Quantum Entanglement and Spin-Orbit Coupling in Crossed Beam Molecular Dynamics Sumit S Kale, Sabre Kais, Junxu Li Non-classical features like interference are already being harnessed to control the output of chemical reactions. However, quantum entanglement which is an equally enigmatic many-body quantum correlation can also be used as a powerful resource yet has eluded explicit attention. In this report, an experimental scheme under the crossed beam molecular dynamical setup, with the F + HD reaction, is proposed aiming to study the possible influence of entanglement within reactant pairs on the angular features of the product distribution. The aforesaid reaction has garnered interest recently, as an unusual horseshoe shape pattern in the product (HF) distribution was observed, which has been attributed to the coupling of spin and orbital degrees of freedom. An experimental scheme is proposed aiming to study the possible influence of entanglement on the necessity for the inclusion of such spin-orbit characteristics, under circumstances wherein the existence of entanglement and spin-orbit interaction is simultaneously detectable. The attainable results are further numerically simulated highlighting specific patterns corresponding to various possibilities. Such studies if extended can provide unforeseen mechanistic insight into analogous reactions, too, from the lens of quantum information. |
Friday, March 18, 2022 8:36AM - 8:48AM |
Y01.00004: Polariton-mediated coupling of spatially separated quasi-degenerate porphyrin excitons. Aleksandr Avramenko, Aaron Rury When an ensemble of excitons strongly couples to single photons in a nano scale Fabry-Perot (FP) cavity, one drives the formation of hybrid light-matter states known as cavity polaritons. Previous studies have proposed polaritons formed from nearly degenerate Frenkel and Wannier-Mott excitons drives a photon-mediated entanglement of spatially separated material excitations across all light-matter coupling conditions. However, it remains unclear in what limit of near degeneracy these results exist and how to characterize similar entanglement for excitons stemming from highly disordered molecular ensembles. Previous studies show the Soret transition of porphyrin molecules enables the formation of robust molecular exciton cavity polaritons whose properties change relative to free space conditions. In this study, we form cavity polaritons using two quasi-degenerate porphyrin molecules, H2TPP, and CuTPP, by strongly coupling them to cavity photons in a multilayer FP resonator structure. We show that despite their apparent degeneracy in linear absorption spectra, the fraction of the H2TPP and CuTPP excitons in each polariton branch will vary as the cavity photon energy is tuned through its dispersion curve. The ability to tune the photonic and excitonic fraction of the polariton energy levels could be a pathway to create optical devices with selectively engineered optical properties. |
Friday, March 18, 2022 8:48AM - 9:00AM |
Y01.00005: The role of topological disorder and heterogeneity on the dissolution kinetics of glasses Luis A Ruiz Pestana The quest for sustainable concrete has led to the search of materials with a low-carbon footprint, known as supplementary cementitious materials (SCMs), that can substitute ordinary Portland cement (OPC) as binder. The major bottleneck limiting the replacement of OPC by SCMs is the slower reactivity of the latter, which results in insufficient early-strength development of the cement paste. As a result, there is a pressing need for discovering or designing new, highly reactive SCM formulations. However, our understanding of the dissolution kinetics of SCMs, which are made of calcium aluminosilicate (CAS) amorphous phases arranged in complex morphologies, remains very limited. Here, we use kinetic Monte Carlo simulations on a model system of a 3-D SCM particle to systematically investigate the role of topological disorder and multiphase morphology on the far-from-equilibrium dissolution kinetics. We find an interesting complex interplay between the average topological disorder in the particle, which is correlated to the average activation barrier associated to the dissolution events, and the heterogeneous distribution of that topological disorder in the particle. For high average activation barriers (i.e., more crystalline SCMs), heterogeneity in the topological disorder slows down dissolution, which is in agreement with our theoretical expectations. However, for low average activation barriers, increased heterogeneity speeds up dissolution. We show that his non-trivial, counterintuitive behavior arises from the incongruent dissolution mechanism of these systems and the fact that dissolution is a non-equilibrium, path-dependent process. Our results provide fundamental insight into the fundamental mechanisms that govern the dissolution kinetics of complex disordered materials like SCMs. |
Friday, March 18, 2022 9:00AM - 9:12AM |
Y01.00006: Ammonia formation on hexagonal Molybdenum Nitride Surfaces using DFT with added van der Waals effects Muhammad Sajid, William Kaden, Abdelkader Kara It has been estimated that Ammonia production is responsible for 2% of world energy consumption. It is produced industrially by the reaction of H2 and N2 gases through Haber-Bosch catalytic reaction over Iron based catalysts which require extreme pressures and temperatures. Though, Ru-based catalysts involve milder conditions with more activity, they are ruled out due to high cost of Ru metal. In order to produce “greener ammonia”, development of efficient as well as cheap alternate catalysts is necessary. In recent years, scientific community has shown great interest in Molybdenum Nitride based materials as potential catalysts for Ammonia production. |
Friday, March 18, 2022 9:12AM - 9:24AM |
Y01.00007: Characterization of light-induced potentials in the strong-field dissociation of O2+ Paul Abanador, Uwe Thumm We examine the imprints of light-induced potentials (LIPs) on the dissociation dynamics of O2+ molecular ions, as observed in the angle-resolved fragment kinetic-energy-release (KER) spectra. By numerically solving the time-dependent Schrödinger equation within the Born-Oppenheimer approximation, we follow the vibrational and rotational motion of O2+ molecular ions exposed to 800-nm, 40-fs laser pulses. For peak intensities between 1013 and 1014 W/cm2, we calculate angle-resolved KER spectra which reveal characteristic energy- and angle-dependent fringe structures associated with the LIPs. |
Friday, March 18, 2022 9:24AM - 9:36AM |
Y01.00008: Insights into the formation of methane and methanol via photocatalytic water splitting in in the presence of methyl iodide on a TiO2(100) surface MIhai E Vaida The detection of intermediate species during surface photoinduced and photocatalytic reactions and the correlation of their dynamics with the properties of a surface is crucial to fully understand and control heterogeneous reactions. In this study, a novel technique that combines time-of-flight mass spectrometry with laser spectroscopy and fast surface preparation with molecules is employed to investigate the mechanism of photoinduced reactions through the direct detection of intermediate species and final products. As a model system, the photoinduced reaction of D2O in the presence of CH3I is investigated on an n-type (Nb) doped TiO2(100) and surface. The reaction is induced by a femtosecond (fs) laser pulses with the central wavelength at 266 nm that triggers the photocatalytic water splitting and simultaneously the photodissociation of the CH3I molecule via A-band excitation. A subsequent fs laser pulse in the UV domain is used to ionize the reaction intermediates and final products, which are immediately analyzed by the TOF-MS. Intermediates such as D, OD, and DO2 radicals are detected when only water is dosed on TiO2. When both D2O and CH3I are dosed on the surface, besides the intermediate species mention above, CH3 and I radicals as well as methane (CH3D) and methanol (CH3OD) are observed. This indicates that D and OD radicals obtained via water splitting can attach to CH3 radicals to form methane and methanol. Details about the surface properties and how this affects the surface chemical reactions will be provided. |
Friday, March 18, 2022 9:36AM - 9:48AM |
Y01.00009: Quantum dynamics simulation of intramolecular singlet fission in covalently linked tetracene dimer Sam Mardazad Organic solar cells provide the possibility to enhance the efficiency and to overcome the Shockley-Queisser limit. In this talk we present results for the simulation of quantum transport effects in a tetracene para dimers, a large organic molecule modelled by a Frenkel-exciton Hamiltonian. We account for the full quantum dynamics going beyond the Born-Oppenheimer approximation. For that purpose we use a new numerically unbiased representation of the molecule's wave function enabling us to compare with experiments, exhibiting good agreement. With this powerful approach we map out a phase diagram aiming and determining the experimental sweet spot yielding the highest charge carrier production rate. Furthermore, we develop a physical picture indicating that the coherent time scale in which most of the yield is generated is driven by a renormalization of the bare modes and make suggestions on how to manipulate this for the development of more efficient organic solar cells. |
Friday, March 18, 2022 9:48AM - 10:00AM |
Y01.00010: Non-Hermitian topology in a spatially-extended system of chemical reactions Tamoghna Das, Tsvi Tlusty A system of reaction-diffusion-advection is studied on a two-dimensional lattice. We show that the interplay between advection, diffusion, and reaction gives rise to non-Hermitian phenomena, in particular exceptional points related to symmetry breaking. We discuss a minimal theoretical framework to characterize such exotic topological phenomena and possible experimental realizations. |
Friday, March 18, 2022 10:00AM - 10:12AM |
Y01.00011: Exploring Chiral-Induced Spin Selectivity using Nitrogen–Vacancy Centers in Diamond John M Abendroth Spin-dependent and enantioselective interactions between electrons and non-identical mirror-image molecules, described by chiral-induced spin selectivity (CISS), enable chiral molecules to polarize spins sans external magnetic fields. This has broad applicability in chemical analysis, spintronics, quantum sciences, and biology. However, advancement in the field is limited by lack of unifying mechanisms and difficulty in detecting spin dynamics in complex systems. New methods are needed to test possible mechanistic roles of magnetic exchange-related effects and spin coherence in CISS. In this talk, the nitrogen–vacancy (NV) center in diamond is introduced as a novel quantum sensing platform to investigate CISS in adsorbed molecules. The optically detected magnetic resonance of NVs can be used to measure localized magnetic fields due to CISS that can arise at chiral molecule–diamond interfaces. Routes are described to overcome sensing limits of shallow NVs, i.e. charge state instability and decoherence, while enabling robust chemical functionalization. Optimizing diamond surface chemistry and optical detection methods provides new avenues toward much needed tests of spin polarization and magnetization resulting from electron transport in chiral molecules. |
Friday, March 18, 2022 10:12AM - 10:24AM |
Y01.00012: Quantum Monte Carlo study on Van der Waals interactions in hydrogen adsorption on a silicon-carbide nanotube Genki I Prayogo, Hyeondeok Shin, Anouar Benali, Ryo Maezono, Kenta Hongo Hydrogen is one of the alternatives being pursued for a clean energy resource. In order to remain competitive with other technologies, further improvements to its storage capacity and safety are necessary. Physisorption on high surface area nanostructures is one of the promising material-based solution to the problem. This solution relies on van der Waals (vdW) interaction to bind the hydrogen, with ideal interaction energy estimated at around 3.5-11.5 kcal/mol for achieving optimal adsorption at room temperature. To accelerate screening of materials capable of achieving these values, a reliable materials simulation scheme is essential. Unfortunately, vdW interaction is not treated by conventional density functional theory (DFT). Recent years have seen the development of new vdW corrections to the DFT based on diverse approach, ranging from simpler pairwise corrections to nonlocal functionals; however their accuracy can be strongly dependent on the studied system. In this work we applied, for the first time, diffusion Monte Carlo (DMC) to model the interaction of hydrogen on an (5,5) armchair silicon carbide nanotube (SiCNT) [1]. Unlike DFT, DMC is able to directly capture the dispersion interactions through stochastic solution of the exact many-body Hamiltonian. This provides a reliable benchmark for the vdW corrections. We found all of the tested vdW corrections to be reasonably accurate, thus present a clear improvement over conventional DFT. The vdW contribution to the adsorption was not insignificant at about 1 kcal/mol or 9-29% of the expected adsorption energy. |
Friday, March 18, 2022 10:24AM - 10:36AM |
Y01.00013: Benchmark all-electron ab initio quantum Monte Carlo calculations with Antisymmetrized Geminal Power (AGP) and Pfaffian Ansatz for G2-set molecules using TurboRVB package Abhishek Raghav, Ryo Maezono, Kenta Hongo, Sandro Sorella, Kousuke Nakano In this work, we report accurate binding energy calculations for 55 molecules in the G2 set, using lattice regularized diffusion Monte Carlo (LRDMC) within TurboRVB quantum Monte Carlo package. We employ both the more traditional Ansatz namely the Jastrow Slater Determinant (referred here as JDFT) as well as the more flexible Ansatz namely the Jastrow antisymmetrized geminal power with singlet correlation (JAGPs) and the Pfaffian (Pf) including both singlet and triplet correlations. Being the most general electron pairing function, we expect the Pfaffian Ansatz to be the most efficient in determining the correlation energy. The many-body wave functions are first optimized at the variational Monte Carlo (VMC) level (Jastrow factor + nodal surface optimization), followed by the LRDMC projection of the Ansatz. Remarkably, for many molecules the LRDMC binding energies obtained using the JAGPs Ansatz reach the chemical accuracy (~1 kcal/mol) and for most of the other cases the binding energies are accurate within ~5 kcal/mol. We further expect to improve upon the JAGPs binding energies by using the Pfaffian Ansatz. This work shows the effectiveness of these more flexible Ansatz in TurboRVB code for binding energy calculations and electronic simulations in general. |
Friday, March 18, 2022 10:36AM - 10:48AM |
Y01.00014: Semi-empirical Quantum Optics for Mid-Infrared Molecular Nanophotonics Felipe Herrera, Johan F Triana, Mauricio Arias, Jun Nishida, Markus B Raschke, Roland Wilcken, Eric Muller, Samuel C Johnson, Aldo Delgado Nanoscale infrared resonators with sub-diffraction mode volumes are new platforms for implementing cavity QED at room temperature. Infrared nano-antennas and tip probes are ideal for studying vibrational strong coupling and for implenting quantum control schemes with nanometer and femtosecond resolution. We develop a general semi-empirical quantum optics approach to describe vibration-tip-antenna interactions under femtosecond laser driving [1]. The theory reproduces recent experiments on the acceleration of the vibrational relaxation rate in nanostructures and gives physical insights for the implementation of coherent phase rotations of the near-field using broadband nanotips. We apply the quantum framework to construct tip-design rules for the experimental manipulation of vibrational strong coupling and Fano interference effects in open infrared resonators, and propose a feasible scheme for transfering the anharmonicity of molecular vibrations to the resonator near-field in weak coupling for implementing nonlinear phase shifts in the coupled infrared response of the system. Our work can facilitate the rapid design of infrared nanophotonic hardware for applications in quantum control of materials, infrared quantum metrology, and quantum information processing [2-5]. |
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