Eric Bittner - Academia.edu (original) (raw)
Papers by Eric Bittner
arXiv (Cornell University), Mar 10, 2022
The lineshape of spectroscopic transitions offer windows into the local environment of a system. ... more The lineshape of spectroscopic transitions offer windows into the local environment of a system. Here, we present a novel approach for connecting the lineshape of a molecular exciton to finite-temperature lattice vibrations within the context of the Davydov soliton model (A. S. Davydov and N. I. Kislukha, Phys. Stat. Sol. 59,465(1973)). Our results are based upon a numerically exact, self-consistent treatment of the model in which thermal effects are introduced as fluctuations about the zero-temperature localized soliton state. We find that both the energy fluctuations and the localization can be described in terms of a parameter-free, reduced description by introducing a critical temperature below which exciton self-trapping is expected to be stable. Above this temperature, the self-consistent ansatz relating the lattice distortion to the exciton wavefunction breaks down. Our theoretical model coorelates well with both experimental observations on molecular J-aggregate and resolves one of the critical issues concerning the finite temperature stability of soliton states in alpha-helices and protein peptide chains.
The Journal of Physical Chemistry C, 2022
The homogeneous photoluminescence spectral linewidth in semiconductors carries a wealth of inform... more The homogeneous photoluminescence spectral linewidth in semiconductors carries a wealth of information on the coupling of primary photoexcitations with their dynamic environment as well as between multi-particles. In the limit in which inhomogeneous broadening dominates the total optical linewidths, the inhomogeneous and homogeneous contributions can be rigorously separated by temperature-dependent steadystate photoluminescence spectroscopy. This is possible because the only temperaturedependent phenomenon is optical dephasing, which defines the homogeneous linewidth, since this process is mediated by scattering with phonons. However, if the homogeneous and inhomogeneous linewidths are comparable, as is the case in hybrid Ruddlesden-Popper metal halides, the temperature dependence of linear spectral measurement cannot separate rigorously the homogeneous and inhomogeneous contributions to the total linewidth because the lineshape does not contain purely Lorentzian components that can be isolated by varying the temperature. Furthermore, the inhomogeneous contribution to the steady-state photoluminescence lineshape is not necessarily temperature independent if driven by diffusion-limited processes, particularly if measured by photoluminescence. Nonlinear coherent optical spectroscopies, on the other hand, do permit separation of homogeneous and inhomogeneous line broadening contributions in all regimes of inhomogeneity. Consequently, these offer insights into the nature of many-body interactions that are entirely inaccessible to temperature-dependent linear spectroscopies. When applied to Ruddlesden-Popper metal halides, these techniques have indeed enabled us to quantitatively assess the exciton-phonon and exciton-exciton scattering mechanisms. Here, we will discuss our perspective on how the coherent lineshapes of Ruddlesden-Popper metal halides can be effectively rationalized within an exciton polaron framework.
Science Advances, 2021
Bound primary photoexcitation pairs are characterized in semiconductor polymers.
molecular geometry by strong light-matter coupling? Eric R. Bittner, a) Ravyn A. Malatesta, Gabri... more molecular geometry by strong light-matter coupling? Eric R. Bittner, a) Ravyn A. Malatesta, Gabrielle D. Olinger, and Carlos Silva-Acuña 4 Department of Chemistry, University of Houston, Houston, TX 77204 School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30332 Department of Physics, University of Houston, Houston, TX 77204 School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332
The Journal of Chemical Physics, 2020
We develop a stochastic theory that treats time-dependent exciton-exciton s-wave scattering and t... more We develop a stochastic theory that treats time-dependent exciton-exciton s-wave scattering and that accounts for dynamic Coulomb screening, which we describe within a mean-field limit. With this theory, we model excitation-induced dephasing effects on timeresolved two-dimensional coherent optical lineshapes and we identify a number of features that can be attributed to the many-body dynamics occurring in the background of the exciton, including dynamic line narrowing, mixing of real and imaginary spectral components, and multi-quantum states. We test the model by means of multidimensional coherent spectroscopy on a two-dimensional metal-halide semiconductor that hosts tightly bound excitons and biexcitons that feature strong polaronic character. We find that the exciton nonlinear coherent lineshape reflects many-body correlations that give rise to excitation-induced dephasing. Furthermore, we observe that the exciton lineshape evolves with population time over time windows in which the population itself is static, in a manner that reveals the evolution of the multi-exciton many-body couplings. Specifically, the dephasing dynamics slow down with time, at a rate that is governed by the strength of exciton many-body interactions and on the dynamic Coulomb screening potential. The real part of the coherent optical lineshape displays strong dispersive character at zero time, which transforms to an absorptive lineshape on the dissipation timescale of excitation-induced dephasing effects, while the imaginary part displays converse behavior. Our microscopic theoretical approach is sufficiently flexible to allow for a wide exploration of how system-bath dynamics contribute to linear and non-linear time-resolved spectral behavior.
Chemistry of Materials, 2019
Nature communications, Jan 24, 2017
We report upon an analysis of the vibrational modes that couple and drive the state-to-state elec... more We report upon an analysis of the vibrational modes that couple and drive the state-to-state electronic transfer branching ratios in a model donor-bridge-acceptor system consisting of a phenothiazine-based donor linked to a naphthalene-monoimide acceptor via a platinum-acetylide bridging unit. Our analysis is based upon an iterative Lanczos search algorithm that finds superpositions of vibronic modes that optimize the electron/nuclear coupling using input from excited-state quantum chemical methods. Our results indicate that the electron transfer reaction coordinates between a triplet charge-transfer state and lower lying charge-separated and localized excitonic states are dominated by asymmetric and symmetric modes of the acetylene groups on either side of the central atom in this system. In particular, we find that while a nearly symmetric mode couples both the charge-separation and charge-recombination transitions more or less equally, the coupling along an asymmetric mode is far...
Chemical Physics, 2016
We report a theoretical description and experimental implementation of a novel two-dimensional co... more We report a theoretical description and experimental implementation of a novel two-dimensional coherent excitation spectroscopy based on quasi-steady-state photoinduced absorption measurement of a long-lived nonlinear population. We have studied a semiconductor-polymer:fullerene-derivative distributed heterostructure by measuring the 2D excitation spectrum by means of photoluminescence, photocurrent and photoinduced absorption from metastable polaronic products. We conclude that the photoinduced absorption probe is a viable and valuable probe in this family of 2D coherent spectroscopies.
The Journal of Chemical Physics, 1995
The Journal of Chemical Physics, 1994
He scattering from Xe monolayers adsorbed onto Ag substrates is studied using a quantum stochasti... more He scattering from Xe monolayers adsorbed onto Ag substrates is studied using a quantum stochastic method. Both the He atom and the surface and bulk modes are treated quantum mechanically using a mean-field partitioning of the quantum Liouville equation. The resulting equations of motion permit the evaluation of the reduced density matrix of the He atom subsystem by averaging over a series of "quantum trajectories." The final reduced density matrix of the atomic subsystem, when projected onto the asymptotic states, provides an accurate estimate of energy transfer processes between the atom and the surface. Our calculations indicate that inelastic energy transfer is enhanced near adsorption resonances due primarily to the increased lifetime of the atom near the surfaces as evidenced by marked deviations from the Debye-Waller thermal attenuation rates.
Computing in Science & Engineering, 2003
uantum dynamical descriptions of chemical systems help us elucidate and understand chemical react... more uantum dynamical descriptions of chemical systems help us elucidate and understand chemical reactivity, 2 COMPUTING IN SCIENCE & ENGINEERING
arXiv preprint quant-ph/0302088, Feb 11, 2003
Abstract: Although the foundations of the hydrodynamical formulation of quantum mechanics were la... more Abstract: Although the foundations of the hydrodynamical formulation of quantum mechanics were laid over 50 years ago, it has only been within the past few years that viable computational implementations have been developed. One approach to solving the hydrodynamic equations uses quantum trajectories as the computational tool. The trajectory equations of motion are described and methods for implementation are discussed, including fitting of the fields to gaussian clusters.
The Journal of Chemical Physics
Spectral line shapes provide a window into the local environment coupled to a quantum transition ... more Spectral line shapes provide a window into the local environment coupled to a quantum transition in the condensed phase. In this paper, we build upon a stochastic model to account for non-stationary background processes produced by broad-band pulsed laser stimulation, as distinguished from those for stationary phonon bath. In particular, we consider the contribution of pair-fluctuations arising from the full bosonic many-body Hamiltonian within a mean-field approximation, treating the coupling to the system as a stochastic noise term. Using the Itô transformation, we consider two limiting cases for our model, which lead to a connection between the observed spectral fluctuations and the spectral density of the environment. In the first case, we consider a Brownian environment and show that this produces spectral dynamics that relax to form dressed excitonic states and recover an Anderson–Kubo-like form for the spectral correlations. In the second case, we assume that the spectrum is ...
arXiv: Materials Science, 2017
Organic Photovoltaic devices (OPVs) are becoming adequately cost and energy efficient to be consi... more Organic Photovoltaic devices (OPVs) are becoming adequately cost and energy efficient to be considered a good investment and it is, therefore, especially important to have a concrete understanding of their operation. We compute energies of charge-transfer (CT) states of the model donor-acceptor lattice system with varying degrees of structural disorder to investigate how fluctuations in the material properties affect electron-hole separation. We also demonstrate how proper statistical treatment of the CT energies recovers experimentally observed "hot" and "cold" exciton dissociation pathways. Using a quantum mechanical model for a model heterojunction interface, we recover experimental values for the open-circuit voltage at 50 and 100meV of site-energy disorder. We find that energetic and conformational disorder generally facilitates charge transfer; however, due to excess energy supplied by photoexcitation, highly energetic electron-hole pairs can dissociate in ...
Advances in Chemical Physics, May 11, 2018
We present a novel ab initio approach for computing intramolecular charge and energy transfer rat... more We present a novel ab initio approach for computing intramolecular charge and energy transfer rates based upon a projection operator scheme that parses out specific internal nuclear motions that accompany the electronic transition. Our approach concentrates the coupling between the electronic and nuclear degrees of freedom into a small number of reduced harmonic modes that can be written as linear combinations of the vibrational normal modes of the molecular system about a given electronic minima. Using a time-convolutionless master-equation approach, parameterized by accurate quantum-chemical methods, we benchmark the approach against experimental results and predictions from Marcus theory for triplet energy transfer for a series of donor-bridge-acceptor systems. We find that using only a single reduced mode-termed the "primary" mode, one obtains an accurate evaluation of the golden-rule rate constant and insight into the nuclear motions responsible for coupling the initial and final electronic states. We demonstrate the utility of the approach by computing the inelastic electronic transition rates in a model donor-bridge-acceptor complex that has been experimentally shown that its exciton transfer pathway can be radically modified by mode-specific infrared excitation of its vibrational mode.
The Journal of Chemical Physics, 2020
Quantum entangled photons provide a sensitive probe of many-body interactions and offer an unique... more Quantum entangled photons provide a sensitive probe of many-body interactions and offer an unique experimental portal for quantifying many-body correlations in a material system. In this paper, we present a theoretical demonstration of how photon-photon entanglement can be generated via interactions between coupled qubits. Here we develop a model for the scattering of an entangled pair of photons from a molecular dimer. We develop a diagrammatic theory for the scattering matrix and show that one can correlate the von Neumann entropy of the outgoing bi-photon wave function to exciton exchange and repulsion interactions. We conclude by discussing possible experimental scenarios for realizing these ideas.
Physical Review Research, 2020
Quantum Science and Technology, 2017
View the article online for updates and enhancements. Related content Generation, dynamical build... more View the article online for updates and enhancements. Related content Generation, dynamical buildup and detection of bi-and mulipartite entangled states in cavity systems D Pagel and H Fehske-Entangled photon spectroscopy Frank Schlawin-Quantum photonics at telecom wavelengths based on lithium niobate waveguides
We examine the dynamics of polaron recombination in conjugated polymer systems using mixed quantu... more We examine the dynamics of polaron recombination in conjugated polymer systems using mixed quantum classical molecular dynamics. The model treats the particle-hole pair as a fully correlated two-particle quantum mechanical wave function interacting with a one-dimensional classical vibrational lattice. This description allows a natural evolution of the particle-hole wave function from the polaron limit to the exciton limit, and we have performed real-time simulations of the coupled nuclear and electronic dynamics associated with the scattering of polarons into exciton states. We use these simulations to calculate cross sections for exciton formation as a function of spin state, and explore the variation of these cross sections with respect to changes in the magnitude of the particle-hole Coulomb interaction and the effective masses of the quasiparticles. Our results indicate that for an optimal choice of parameters the electroluminescence quantum yield may be as high as 59%, substantially greater than the 25% predicted by simple spin statistics. We interpret these results in a diabatic framework, and suggest strategies for the design of organic systems for use in electroluminescent devices.
The Journal of Chemical Physics, 1997
The role of quantum coherence loss in mixed quantum-classical dynamical systems is explored in th... more The role of quantum coherence loss in mixed quantum-classical dynamical systems is explored in the context of the theory of quantum decoherence introduced recently by Bittner and Rossky ͓J. Chem. Phys. 103, 8130 ͑1995͔͒. This theory, which is based upon the consistent histories interpretation of quantum mechanics, introduces decoherence in the quantum subsystem by carefully considering the relevant time and length scales over which one must consider the effects of phase interference between alternative histories of the classical subsystem. Such alternative histories are an integral part of any quantum-classical computational scheme which employs transitions between discrete quantum states; consequently, the coherences between alternative histories have a profound effect on the transition probability between quantum states. In this paper, we review the Bittner-Rossky theory and detail a computational algorithm suitable for large-scale quantum molecular dynamics simulations which implements this theory. Application of the algorithm towards the relaxation of a photoexcited aqueous electron compare well to previous estimates of the excited state survival time as well as to the experimental measurements.
arXiv (Cornell University), Mar 10, 2022
The lineshape of spectroscopic transitions offer windows into the local environment of a system. ... more The lineshape of spectroscopic transitions offer windows into the local environment of a system. Here, we present a novel approach for connecting the lineshape of a molecular exciton to finite-temperature lattice vibrations within the context of the Davydov soliton model (A. S. Davydov and N. I. Kislukha, Phys. Stat. Sol. 59,465(1973)). Our results are based upon a numerically exact, self-consistent treatment of the model in which thermal effects are introduced as fluctuations about the zero-temperature localized soliton state. We find that both the energy fluctuations and the localization can be described in terms of a parameter-free, reduced description by introducing a critical temperature below which exciton self-trapping is expected to be stable. Above this temperature, the self-consistent ansatz relating the lattice distortion to the exciton wavefunction breaks down. Our theoretical model coorelates well with both experimental observations on molecular J-aggregate and resolves one of the critical issues concerning the finite temperature stability of soliton states in alpha-helices and protein peptide chains.
The Journal of Physical Chemistry C, 2022
The homogeneous photoluminescence spectral linewidth in semiconductors carries a wealth of inform... more The homogeneous photoluminescence spectral linewidth in semiconductors carries a wealth of information on the coupling of primary photoexcitations with their dynamic environment as well as between multi-particles. In the limit in which inhomogeneous broadening dominates the total optical linewidths, the inhomogeneous and homogeneous contributions can be rigorously separated by temperature-dependent steadystate photoluminescence spectroscopy. This is possible because the only temperaturedependent phenomenon is optical dephasing, which defines the homogeneous linewidth, since this process is mediated by scattering with phonons. However, if the homogeneous and inhomogeneous linewidths are comparable, as is the case in hybrid Ruddlesden-Popper metal halides, the temperature dependence of linear spectral measurement cannot separate rigorously the homogeneous and inhomogeneous contributions to the total linewidth because the lineshape does not contain purely Lorentzian components that can be isolated by varying the temperature. Furthermore, the inhomogeneous contribution to the steady-state photoluminescence lineshape is not necessarily temperature independent if driven by diffusion-limited processes, particularly if measured by photoluminescence. Nonlinear coherent optical spectroscopies, on the other hand, do permit separation of homogeneous and inhomogeneous line broadening contributions in all regimes of inhomogeneity. Consequently, these offer insights into the nature of many-body interactions that are entirely inaccessible to temperature-dependent linear spectroscopies. When applied to Ruddlesden-Popper metal halides, these techniques have indeed enabled us to quantitatively assess the exciton-phonon and exciton-exciton scattering mechanisms. Here, we will discuss our perspective on how the coherent lineshapes of Ruddlesden-Popper metal halides can be effectively rationalized within an exciton polaron framework.
Science Advances, 2021
Bound primary photoexcitation pairs are characterized in semiconductor polymers.
molecular geometry by strong light-matter coupling? Eric R. Bittner, a) Ravyn A. Malatesta, Gabri... more molecular geometry by strong light-matter coupling? Eric R. Bittner, a) Ravyn A. Malatesta, Gabrielle D. Olinger, and Carlos Silva-Acuña 4 Department of Chemistry, University of Houston, Houston, TX 77204 School of Chemistry and Biochemistry, Georgia Institute of Technology, 901 Atlantic Drive, Atlanta, GA 30332 Department of Physics, University of Houston, Houston, TX 77204 School of Physics, Georgia Institute of Technology, 837 State Street, Atlanta, GA 30332
The Journal of Chemical Physics, 2020
We develop a stochastic theory that treats time-dependent exciton-exciton s-wave scattering and t... more We develop a stochastic theory that treats time-dependent exciton-exciton s-wave scattering and that accounts for dynamic Coulomb screening, which we describe within a mean-field limit. With this theory, we model excitation-induced dephasing effects on timeresolved two-dimensional coherent optical lineshapes and we identify a number of features that can be attributed to the many-body dynamics occurring in the background of the exciton, including dynamic line narrowing, mixing of real and imaginary spectral components, and multi-quantum states. We test the model by means of multidimensional coherent spectroscopy on a two-dimensional metal-halide semiconductor that hosts tightly bound excitons and biexcitons that feature strong polaronic character. We find that the exciton nonlinear coherent lineshape reflects many-body correlations that give rise to excitation-induced dephasing. Furthermore, we observe that the exciton lineshape evolves with population time over time windows in which the population itself is static, in a manner that reveals the evolution of the multi-exciton many-body couplings. Specifically, the dephasing dynamics slow down with time, at a rate that is governed by the strength of exciton many-body interactions and on the dynamic Coulomb screening potential. The real part of the coherent optical lineshape displays strong dispersive character at zero time, which transforms to an absorptive lineshape on the dissipation timescale of excitation-induced dephasing effects, while the imaginary part displays converse behavior. Our microscopic theoretical approach is sufficiently flexible to allow for a wide exploration of how system-bath dynamics contribute to linear and non-linear time-resolved spectral behavior.
Chemistry of Materials, 2019
Nature communications, Jan 24, 2017
We report upon an analysis of the vibrational modes that couple and drive the state-to-state elec... more We report upon an analysis of the vibrational modes that couple and drive the state-to-state electronic transfer branching ratios in a model donor-bridge-acceptor system consisting of a phenothiazine-based donor linked to a naphthalene-monoimide acceptor via a platinum-acetylide bridging unit. Our analysis is based upon an iterative Lanczos search algorithm that finds superpositions of vibronic modes that optimize the electron/nuclear coupling using input from excited-state quantum chemical methods. Our results indicate that the electron transfer reaction coordinates between a triplet charge-transfer state and lower lying charge-separated and localized excitonic states are dominated by asymmetric and symmetric modes of the acetylene groups on either side of the central atom in this system. In particular, we find that while a nearly symmetric mode couples both the charge-separation and charge-recombination transitions more or less equally, the coupling along an asymmetric mode is far...
Chemical Physics, 2016
We report a theoretical description and experimental implementation of a novel two-dimensional co... more We report a theoretical description and experimental implementation of a novel two-dimensional coherent excitation spectroscopy based on quasi-steady-state photoinduced absorption measurement of a long-lived nonlinear population. We have studied a semiconductor-polymer:fullerene-derivative distributed heterostructure by measuring the 2D excitation spectrum by means of photoluminescence, photocurrent and photoinduced absorption from metastable polaronic products. We conclude that the photoinduced absorption probe is a viable and valuable probe in this family of 2D coherent spectroscopies.
The Journal of Chemical Physics, 1995
The Journal of Chemical Physics, 1994
He scattering from Xe monolayers adsorbed onto Ag substrates is studied using a quantum stochasti... more He scattering from Xe monolayers adsorbed onto Ag substrates is studied using a quantum stochastic method. Both the He atom and the surface and bulk modes are treated quantum mechanically using a mean-field partitioning of the quantum Liouville equation. The resulting equations of motion permit the evaluation of the reduced density matrix of the He atom subsystem by averaging over a series of "quantum trajectories." The final reduced density matrix of the atomic subsystem, when projected onto the asymptotic states, provides an accurate estimate of energy transfer processes between the atom and the surface. Our calculations indicate that inelastic energy transfer is enhanced near adsorption resonances due primarily to the increased lifetime of the atom near the surfaces as evidenced by marked deviations from the Debye-Waller thermal attenuation rates.
Computing in Science & Engineering, 2003
uantum dynamical descriptions of chemical systems help us elucidate and understand chemical react... more uantum dynamical descriptions of chemical systems help us elucidate and understand chemical reactivity, 2 COMPUTING IN SCIENCE & ENGINEERING
arXiv preprint quant-ph/0302088, Feb 11, 2003
Abstract: Although the foundations of the hydrodynamical formulation of quantum mechanics were la... more Abstract: Although the foundations of the hydrodynamical formulation of quantum mechanics were laid over 50 years ago, it has only been within the past few years that viable computational implementations have been developed. One approach to solving the hydrodynamic equations uses quantum trajectories as the computational tool. The trajectory equations of motion are described and methods for implementation are discussed, including fitting of the fields to gaussian clusters.
The Journal of Chemical Physics
Spectral line shapes provide a window into the local environment coupled to a quantum transition ... more Spectral line shapes provide a window into the local environment coupled to a quantum transition in the condensed phase. In this paper, we build upon a stochastic model to account for non-stationary background processes produced by broad-band pulsed laser stimulation, as distinguished from those for stationary phonon bath. In particular, we consider the contribution of pair-fluctuations arising from the full bosonic many-body Hamiltonian within a mean-field approximation, treating the coupling to the system as a stochastic noise term. Using the Itô transformation, we consider two limiting cases for our model, which lead to a connection between the observed spectral fluctuations and the spectral density of the environment. In the first case, we consider a Brownian environment and show that this produces spectral dynamics that relax to form dressed excitonic states and recover an Anderson–Kubo-like form for the spectral correlations. In the second case, we assume that the spectrum is ...
arXiv: Materials Science, 2017
Organic Photovoltaic devices (OPVs) are becoming adequately cost and energy efficient to be consi... more Organic Photovoltaic devices (OPVs) are becoming adequately cost and energy efficient to be considered a good investment and it is, therefore, especially important to have a concrete understanding of their operation. We compute energies of charge-transfer (CT) states of the model donor-acceptor lattice system with varying degrees of structural disorder to investigate how fluctuations in the material properties affect electron-hole separation. We also demonstrate how proper statistical treatment of the CT energies recovers experimentally observed "hot" and "cold" exciton dissociation pathways. Using a quantum mechanical model for a model heterojunction interface, we recover experimental values for the open-circuit voltage at 50 and 100meV of site-energy disorder. We find that energetic and conformational disorder generally facilitates charge transfer; however, due to excess energy supplied by photoexcitation, highly energetic electron-hole pairs can dissociate in ...
Advances in Chemical Physics, May 11, 2018
We present a novel ab initio approach for computing intramolecular charge and energy transfer rat... more We present a novel ab initio approach for computing intramolecular charge and energy transfer rates based upon a projection operator scheme that parses out specific internal nuclear motions that accompany the electronic transition. Our approach concentrates the coupling between the electronic and nuclear degrees of freedom into a small number of reduced harmonic modes that can be written as linear combinations of the vibrational normal modes of the molecular system about a given electronic minima. Using a time-convolutionless master-equation approach, parameterized by accurate quantum-chemical methods, we benchmark the approach against experimental results and predictions from Marcus theory for triplet energy transfer for a series of donor-bridge-acceptor systems. We find that using only a single reduced mode-termed the "primary" mode, one obtains an accurate evaluation of the golden-rule rate constant and insight into the nuclear motions responsible for coupling the initial and final electronic states. We demonstrate the utility of the approach by computing the inelastic electronic transition rates in a model donor-bridge-acceptor complex that has been experimentally shown that its exciton transfer pathway can be radically modified by mode-specific infrared excitation of its vibrational mode.
The Journal of Chemical Physics, 2020
Quantum entangled photons provide a sensitive probe of many-body interactions and offer an unique... more Quantum entangled photons provide a sensitive probe of many-body interactions and offer an unique experimental portal for quantifying many-body correlations in a material system. In this paper, we present a theoretical demonstration of how photon-photon entanglement can be generated via interactions between coupled qubits. Here we develop a model for the scattering of an entangled pair of photons from a molecular dimer. We develop a diagrammatic theory for the scattering matrix and show that one can correlate the von Neumann entropy of the outgoing bi-photon wave function to exciton exchange and repulsion interactions. We conclude by discussing possible experimental scenarios for realizing these ideas.
Physical Review Research, 2020
Quantum Science and Technology, 2017
View the article online for updates and enhancements. Related content Generation, dynamical build... more View the article online for updates and enhancements. Related content Generation, dynamical buildup and detection of bi-and mulipartite entangled states in cavity systems D Pagel and H Fehske-Entangled photon spectroscopy Frank Schlawin-Quantum photonics at telecom wavelengths based on lithium niobate waveguides
We examine the dynamics of polaron recombination in conjugated polymer systems using mixed quantu... more We examine the dynamics of polaron recombination in conjugated polymer systems using mixed quantum classical molecular dynamics. The model treats the particle-hole pair as a fully correlated two-particle quantum mechanical wave function interacting with a one-dimensional classical vibrational lattice. This description allows a natural evolution of the particle-hole wave function from the polaron limit to the exciton limit, and we have performed real-time simulations of the coupled nuclear and electronic dynamics associated with the scattering of polarons into exciton states. We use these simulations to calculate cross sections for exciton formation as a function of spin state, and explore the variation of these cross sections with respect to changes in the magnitude of the particle-hole Coulomb interaction and the effective masses of the quasiparticles. Our results indicate that for an optimal choice of parameters the electroluminescence quantum yield may be as high as 59%, substantially greater than the 25% predicted by simple spin statistics. We interpret these results in a diabatic framework, and suggest strategies for the design of organic systems for use in electroluminescent devices.
The Journal of Chemical Physics, 1997
The role of quantum coherence loss in mixed quantum-classical dynamical systems is explored in th... more The role of quantum coherence loss in mixed quantum-classical dynamical systems is explored in the context of the theory of quantum decoherence introduced recently by Bittner and Rossky ͓J. Chem. Phys. 103, 8130 ͑1995͔͒. This theory, which is based upon the consistent histories interpretation of quantum mechanics, introduces decoherence in the quantum subsystem by carefully considering the relevant time and length scales over which one must consider the effects of phase interference between alternative histories of the classical subsystem. Such alternative histories are an integral part of any quantum-classical computational scheme which employs transitions between discrete quantum states; consequently, the coherences between alternative histories have a profound effect on the transition probability between quantum states. In this paper, we review the Bittner-Rossky theory and detail a computational algorithm suitable for large-scale quantum molecular dynamics simulations which implements this theory. Application of the algorithm towards the relaxation of a photoexcited aqueous electron compare well to previous estimates of the excited state survival time as well as to the experimental measurements.