Bulletin of the American Physical Society
APS March Meeting 2020
Volume 65, Number 1
Monday–Friday, March 2–6, 2020; Denver, Colorado
Session J05: The Chemical Physics of Molecular Polaritons IV. Photophysics 3Focus
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Sponsoring Units: DCP DCMP DPOLY Chair: Raphael Ribeiro, University of California, San Diego Room: 111 |
Tuesday, March 3, 2020 2:30PM - 3:06PM |
J05.00001: Quantum cavities and Floquet materials engineering from first principles QEDFT Invited Speaker: Angel Rubio An appealing and challenging route towards engineering materials with specic properties is to find ways of designing or selectively manipulate materials, especially at the quantum level. We will provide an overview of how well-established concepts in the fields of quantum chemistry and materials have to be adapted when the quantum nature of light becomes important. We will pursue the question whether it is possible to create these new states of materials as groundstates of the system. To this end we will show how the emerging (vaccum) dressed states resembles Floquet states in driven systems. A particular appeal of light dressing is the possibility to engineer symmetry breaking which can lead to novel properties of materials, e.g coupling to circularly polarized photons leads to local breaking of time-reversal symmetry enabling the control over a large variety of materials properties (e.g.topology). We show that the new quantum electrodynamics density-functional formalism (QEDFT) can acocunt for those effects. We illustrate the realisation of those ideas in molecular complexes and 2D materials. |
Tuesday, March 3, 2020 3:06PM - 3:18PM |
J05.00002: Investigating New Reactivities Enabled by Polariton Photochemistry Arkajit Mandal, Pengfei Huo We perform quantum dynamics simulations to investigate new chemical reactivities enabled by cavity quantum electrodynamics. With quantum dynamics simulations, we demonstrate that the selectivity of a model photo-isomerization reaction can be controlled by tuning the photon frequency of the cavity mode or the light-matter coupling strength, providing new ways to manipulate chemical reactions via light-matter interaction. We further investigate collective quantum effects enabled by coupling quantized radiation mode to multiple molecules. Our results suggest that in the resonance case, a photon is recycled among molecules to enable multiple excited state reactions, thus effectively functioning as a catalyst. In the non-resonance case, molecules emit and absorb virtual photons to initiate excited state reactions through fundamental quantum electrodynamics processes. These results from quantum dynamics simulations reveal basic principles of polariton photochemistry as well as promising reactivities that take advantage of intrinsic quantum behaviors of photons. |
Tuesday, March 3, 2020 3:18PM - 3:30PM |
J05.00003: Polariton Mediated Charge Transfer Reaction through Cavity-Quantum Electrodynamics Arkajit Mandal, Pengfei Huo
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Tuesday, March 3, 2020 3:30PM - 4:06PM |
J05.00004: Polaronic effects on exciton-polaritons in two-dimensional metal-halide perovskite microcavities Invited Speaker: Carlos Silva While polarons --- charges bound to a lattice deformation induced by electron-phonon coupling --- are primary photoexcitations at room temperature in bulk metal-halide hybrid organic-inorganic perovskites (HOIP), excitons --- Coulomb-bound el\-ectron-hole pairs --- are the stable quasi-particles in their two-dimensional (2D) analogues. Here we address the fundamental question: are polaronic effects consequential for excitons in 2D-HIOPs? Based on our recent work, we argue that polaronic effects are manifested intrinsically in the exciton spectral structure, which is comprised of multiple non-degenerate resonances with constant inter-peak energy spacing. We highlight our own measurements of population and dephasing dynamics that point to the apparently deterministic role of polaronic effects in excitonic properties. We contend that an interplay of long-range and short-range exciton-lattice couplings give rise to exciton polarons, a character that fundamentally establishes their effective mass and radius, and consequently, their quantum dynamics. Finally. we consider how the exciton spectral struture and dynamics controls exciton-polaron properties in Fabry-Perot microcavities. |
Tuesday, March 3, 2020 4:06PM - 4:18PM |
J05.00005: A variational approach for the dynamics of triplet harvesting in the polariton regime. Luis Angel Martinez Martinez, Elad Eizner, Stephane Kena-Cohen, Joel Yuen-Zhou The recent interest on the manipulation of chemical processes within confined electromagnetic environments has opened up new directions on theoretical efforts to understand the emergent dynamics of organic molecules embedded in the former. |
Tuesday, March 3, 2020 4:18PM - 4:30PM |
J05.00006: Modifying reverse intersystem crossing with cavity polaritons Francesca Fassioli Olsen, Courtney DelPo, Bryan J Kudisch, Kyu Hyung Park, Daniele Fausti, Greg Scholes Strong light-matter coupling gives rise to a superposition of light and matter states called polaritons. In the molecular setting, strong light-matter coupling is usually achieved when a large number of molecules is coupled to the same mode of an optical cavity. In this case, the energy structure is normally described as consisting of two distinct polaritonic states together with a large set of intermediate molecular dark states, that due to their purely molecular nature are believed to exhibit dynamics that resemble those of the bare molecular states. In this work we investigate the nature of these intermediate states and how their dynamics and optical response deviate from those of molecules outside the cavity. We apply our framework to simulate linear and non-linear optical responses of an experimentally studied system, namely 4CzIPN, to gain insight into how these intermediate states are involved in and modify intersystem crossing and reverse intersystem crossing under the strong light matter coupling regime. |
Tuesday, March 3, 2020 4:30PM - 5:06PM |
J05.00007: Multiscale Molecular Dynamics Simulations of Polaritonic Chemistry Invited Speaker: Gerrit Groenhof When photoactive molecules interact strongly with confined light modes in optical cavities new hybrid light-matter states form, the polaritons. These polaritons are coherent superpositions of excitations of the molecules and of the cavity mode. Because light-matter hybridization can change the potential energy surface with respect to the bare molecules, polaritons are considered a promising paradigm for controlling photochemical reactions. To gain insight into the effects of strong coupling on the reactivity of molecules, we have extended the Tavis-Jaynes-Cummings model into an all-atom hybrid quantum chemistry / molecular mechanics approach, capable of simulating thousands of molecules inside cavities. After presenting our model, we will discuss recent simulations that illustrate how the dynamics and reactivity of large ensembles of molecules are affected by their strong interaction with the confined light modes of the cavity. |
Tuesday, March 3, 2020 5:06PM - 5:18PM |
J05.00008: Polariton assisted down-conversion of photons via nonadiabatic molecular dynamics: a molecular dynamical Casimir effect Juan Perez-Sanchez, Joel Yuen-Zhou Recently it has been possible to reach new regimes in which the light-matter interaction energy is comparable to electronic or vibrational energies using optical microcavities or nanostructures, giving rise to new hybrid light-matter states called polaritons. Most recent works focus on using strong light-matter coupling to change molecular processes such as photodissociation and charge and energy transfer.Here, we focus on a less addressed complementary question: can the emergent molecular dynamics be harnessed for photonic applications? We calculate the quantum dynamics of the photoisomerization of a single molecule embedded in an optical microcavity. We found that for specific cavity frequencies and sufficiently strong couplings, molecular photoexcitation into an electronic excited state can be followed by the spontaneous emission of two photons of a lower frequency via the cavity after isomerization, thus offering a new mechanism for photonic down-conversion using molecular polaritons. We show how this mechanism occurs when the light-matter coupling is strong enough so the nuclear dynamics cannot be considered to be adiabatic with respect to the electronic and photonic degrees of freedom. |
Tuesday, March 3, 2020 5:18PM - 5:30PM |
J05.00009: Cavity controlled inverse harmonic generation Davis Dave Welakuh, Mary-Leena Martine Tchenkoue Djouom, Michael Ruggenthaler, Heiko Appel, Angel Rubio Interaction between quantized light and matter lies at the heart of a broad range of applications, such as frequency down-conversion in ultrastrong cavity QED [1]. Frequency down-conversion schemes are often treated with few-level approximations of the matter subsystem. In the present work, we consider the case of a semiconductor quantum ring described in real space coupled to more than one mode and investigate a down-conversion process. We show that the down-converted photons have unique features such as non-classicality and entanglement. In addition, we show shortcomings of few-level approximations and mean-field theory. An interesting outcome for down-conversion is that ultrastrong coupling is more efficient than just increasing the incoming field strength. |
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