Strong light-matter coupling in optical cavities is being widely explored as a strategy for modifying molecular dynamics and enhancing coherence. At the same time, structured vibrational environments can exhibit non-Markovian memory that promotes information backflow and coherence revival. We investigate the competition between these effects in a vibronic molecular system strongly coupled to a lossy optical cavity. Using hierarchical equations of motion to treat structured vibrational baths, we quantify both system coherence and non-Markovianity via the l1 norm of coherence and the Breuer-Laine-Piilo measure, respectively. We find that cavity coupling enhances coherence in overdamped environments but can suppress memory-assisted coherence in resonant underdamped regimes, even in the absence of significant photon loss. This suppression arises from hybridization-induced modification of system-bath information flow. We demonstrate that cavity coupling does not universally protect coherence but establishes limits governed by the competition between vibrational recurrence time scales and polaritonic hybridization.
Strong light-matter coupling in optical cavities is being widely explored as a strategy for modifying molecular dynamics and enhancing coherence. At the same time, structured vibrational environments can exhibit non-Markovian memory that promotes information backflow and coherence revival. We investigate the competition between these effects in a vibronic molecular system strongly coupled to a lossy optical cavity. Using hierarchical equations of motion to treat structured vibrational baths, we quantify both system coherence and non-Markovianity via the l1 norm of coherence and the Breuer-Laine-Piilo measure, respectively. We find that cavity coupling enhances coherence in overdamped environments but can suppress memory-assisted coherence in resonant underdamped regimes, even in the absence of significant photon loss. This suppression arises from hybridization-induced modification of system-bath information flow. We demonstrate that cavity coupling does not universally protect coherence but establishes limits governed by the competition between vibrational recurrence time scales and polaritonic hybridization.
In an optical cavity, strong light-matter coupling between excitons and photons has been widely reported as a way to enhance energy delocalization through spatially extended polaritonic states. In contrast, leveraging cavity-mediated light-matter effects to promote the reciprocal phenomenon, namely, energy localization, remains largely underexplored. In the present work, we address this question by focusing on a special form of energy localization arising from nonlinear matter interactions: quantum self-trapping (QST). We employ a generalized Tavis-Cummings model to investigate the transport of vibrational excitons, i.e., vibrons, between two anharmonic vibrational modes and examine their interplay with cavity photons. In the absence of a cavity, the arising of true and complete QST, i.e., a fully stabilized localization, is not possible due to the symmetry of the system. The energy transfer between the two modes still occurs, slowed down by the many-body interactions. Coupling the system to a single-mode cavity strongly alters this behavior, with two emerging regimes. First, at weak light-matter coupling, destructive interference between newly opened transition pathways suppresses energy exchange, leading to cavity-enhanced self-trapping. As the coupling strength increases, these interference effects evolve, leading to cavity-assisted energy transfer, where we observe an acceleration of the vibrational energy flow. Most notably, we identify critical coupling strengths that separate both regimes in which the dynamics almost totally freeze, suggesting the arising of a “stabilized” light-induced QST of many-vibron bound states. These results suggest that optical cavities can not only enhance transport but could also stabilize energy localization phenomena, providing a route to control energy flow in quantum systems.
In an optical cavity, strong light--matter coupling between excitons and photons has been widely reported as a way to enhance energy delocalization through spatially extended polaritonic states. In contrast, leveraging cavity-mediated light--matter effects to promote the reciprocal phenomenon, namely \textit{energy localization}, remains largely underexplored. In the present work, we address this question by focusing on a special form of energy localization arising from nonlinear matter interactions: \textit{Quantum Self-Trapping} (QST). We employ a generalized Tavis--Cummings model to investigate the transport of vibrational excitons -- \textit{i.e., vibrons} -- between two anharmonic vibrational modes and examine their interplay with cavity photons. In the absence of a cavity, the arising of true and complete QST -- \textit{i.e.}, an infinite-lifetime localization -- is not possible due to the symmetry of the system. The energy transfer between the two modes still occurs, slowed down by the many-body interactions. Coupling the system to a single-mode cavity strongly alters this behavior, with two emerging regimes. First, at weak light--matter coupling, destructive interference between newly opened transition pathways suppresses energy exchange, leading to cavity-enhanced self-trapping. As the coupling strength increases, these interference effects evolve leading to cavity-assisted energy transfer, where we observe an acceleration of the vibrational energy flow. Most notably, we identify critical coupling strengths that separate both regimes in which the dynamics almost totally freeze, suggesting the arising of a ``stabilized'' light-induced~QST of many-vibron bound states. These results suggest that optical cavities can not only enhance transport but could also stabilize energy localization phenomena, providing a new route to control energy flow in quantum systems.
We investigate qubit entanglement dynamics in a two-qubit cavity system with stochastically fluctuating coupling strength, comparing white noise (Markovian) and Ornstein-Uhlenbeck noise (non-Markovian) processes. We analytically solve the system dynamics for both Fock and coherent cavity states and systematically characterize how initial qubit configurations affect entanglement generation and preservation. Our results reveal distinct dynamical regimes: in the Fock-state cavity, initial states in the single-excitation subspace generate robust qubit entanglement in decoherence-free subspaces, while initially entangled states in the double-excitation subspace exhibit inevitable decay without protective symmetries. For coherent cavities, we identify a critical photon-number threshold in the intermediate coherent-state amplitude regime where dynamics transition from low-frequency to high-frequency entanglement oscillations, while universal entanglement loss occurs at large amplitudes. Remarkable resilience against entanglement sudden death emerges under strong non-Markovian noise with long correlation times, where repeated revivals occur. These findings establish cavity photon statistics and environmental memory time as key control parameters for engineering qubit entanglement dynamics in qubit-cavity systems, revealing how system-environment correlations govern quantum information preservation.
High Resolution Image Download MS PowerPoint Slide Protecting quantum coherences in matter from the detrimental effects introduced by its environment is essential to employ molecules and materials in quantum technologies and develop enhanced spectroscopies. Here, we show how dressing molecular chromophores with quantum light in the context of optical cavities can be used to generate quantum superposition states with tunable coherence time scales that are longer than those of the bare molecule, even at room temperature and for molecules immersed in solvent. For this, we develop a theory of decoherence rates for molecular polaritonic states and demonstrate that quantum superpositions that involve such hybrid light-matter states can survive for times that are orders of magnitude longer than those of the bare molecule while remaining optically controllable. Further, by studying these tunable coherence enhancements in the presence of lossy cavities, we demonstrate that they can be enacted using present-day optical cavities. The analysis offers a viable strategy to engineer and increase quantum coherence lifetimes in molecules.
Strong coupling between molecular excitations and quantized electromagnetic fields in optical cavities provides a powerful means to control the physical and chemical properties of molecular systems. Here, we study electron transfer (ET) dynamics in cavity-coupled molecules using the numerically exact hierarchical equations of motion (HEOM) method, which captures nonperturbative and non-Markovian effects beyond standard perturbative theories. We identify distinct resonance and collective effects associated with polariton formation and show that the ET rate saturates in the strong-coupling regime, a feature not captured by perturbative approaches. We further extend the cavity-modified ET model by incorporating the nuclear-coordinate dependence of molecular electric dipole moments, which gives rise to a three-body interaction involving molecular electronic and vibrational degrees of freedom and cavity photons. This vibronic polariton formation leads to non-monotonic, oscillatory dependencies of the ET rate on the light-matter coupling strength and cavity frequency, which we attribute to quantum interference among multiple transfer pathways. These findings establish cavity-modified electron transfer as a multichannel quantum process governed by the interplay of electronic, vibrational, and photonic degrees of freedom.
The field of Polaritonic Chemistry studies molecules strongly coupled to the light field of optical cavities. The resulting modification of the potential energy landscape has been demonstrated to enable control over the chemical and physical properties of materials and molecular ensembles. This thesis extends the Tavis–Cummings model to describe molecules under strong light–matter coupling, incorporating static dipole moments and dipole self-energy contributions derived from the Pauli–Fierz Hamiltonian. These additional terms are shown to be essential for reproducing cavity-modified molecular dynamics and spectra. Simulations on the nuclear wavefunction propagation of MgH+ molecules demonstrate the impact of these terms, while an effective two-level system model accurately captures the behavior of large ensembles. Beyond single excitations, the thesis also explores the higher excitation manifolds of the Tavis-Cummings model, which reveals that allowing for more than a single excitation makes the reaction of the involved polaritons entropically more favorable. Open-system simulations highlight how the coherence of the system's initial state governs decay pathways and enables long-lived energy storage. Finally, a multilevel vibrational model coupled to a two-mode cavity is introduced, where a Raman scheme enables selective mixing of vibrational states. The simulation results show that continuous pumping can drive molecules into specific vibrational states while suppressing electronic excitation, both for single molecules and small ensembles. Together, these results provide new theoretical insights into the mechanisms by which optical cavities reshape molecular energy landscapes. The results suggest approaches for controlling photonic, electronic, and vibrational dynamics in strongly coupled systems, contributing to the theoretical foundation of polariton chemistry.