The spectral structure of a photonic reservoir shapes radiation phenomena for embedded quantum emitters. We implement an all-optical analog to study such an effect, particularly to observe the non-Markovian radiation dynamics of an emitter coupled to two-dimensional structured reservoirs. Its dynamics is simulated by light propagating through a photonic lattice, acting as a reservoir for an adjacent waveguide that mimics a coupled quantum emitter. We study radiation dynamics in square and Lieb lattices under different coupling regimes and observe how the flat band properties of the Lieb lattice significantly enhances light-matter coupling and non-Markovianity. Our platform opens a path for the experimental exploration of single-photon quantum optical phenomena in structured reservoirs to enhance light-matter interactions.
The spectral structure of a photonic reservoir shapes radiation phenomena for embedded quantum emitters. We implement an all-optical analog to study such an effect, particularly to observe the non-Markovian radiation dynamics of an emitter coupled to two-dimensional structured reservoirs. Its dynamics is simulated by light propagating through a photonic lattice, acting as a reservoir for an adjacent waveguide that mimics a coupled quantum emitter. We study radiation dynamics in square and Lieb lattices under different coupling regimes and observe how the flat band properties of the Lieb lattice significantly enhances light-matter coupling and non-Markovianity. Our platform opens a path for the experimental exploration of single-photon quantum optical phenomena in structured reservoirs to enhance light-matter interactions.
Quantum emitters coupled to structured photonic reservoirs experience unconventional individual and collective dynamics emerging from the interplay between dimensionality and non-trivial photon energy dispersions. In this work, we systematically study several paradigmatic three dimensional structured baths with qualitative differences in their bath spectral density. We discover non-Markovian individual and collective effects absent in simplified descriptions, such as perfect subradiant states or long-range anisotropic interactions. Furthermore, we show how to implement these models using only cold atoms in state-dependent optical lattices and show how this unconventional dynamics can be observed with these systems.
Recent advances are enabling quantum emitters to interact with photonic crystals, whose electromagnetic modes exhibit complex dispersion relations, spatial mode structure, and polarization textures. However, modeling light-matter behavior in these systems faces a persistent trade-off: electromagnetic approaches based on Maxwell-equation solvers provide realistic vectorial descriptions but are difficult to integrate with quantum many-body and non-perturbative methods, whereas simplified quantum-optical lattice models are tractable but typically rely on scalar and spatially independent light-matter couplings that miss essential features of these structured photonic environments. Here, we introduce a constructive framework to derive quantum-optical lattice descriptions that overcome this trade-off. Combining symmetry-constrained tight-binding constructions with numerically computed photonic band structures and field profiles, our method yields minimal, symmetry-enforced lattice Hamiltonians that reproduce the target photonic dispersion while retaining the mode-resolved (position- and polarization-dependent) structure of the light-matter coupling. We show that these models recover Green's-function-based emitter dynamics in the perturbative regime, while providing access to non-perturbative quantum dynamical simulations beyond emitter-only descriptions. As a proof of principle, we apply the framework to a two-dimensional photonic crystal and show that it captures polarization-dependent directional emission inaccessible to scalar models, while enabling the analysis of non-Markovian light-matter dynamics and entanglement. Our results provide a practical bridge between classical electromagnetic simulation tools and quantum-optical many-body and non-Markovian modeling in photonic crystal settings.
The interaction of quantum emitters with structured baths modifies both their individual and collective dynamics. In A. Gonz\'alez-Tudela and J. I. Cirac, Phys. Rev. Lett. 119, 143602 (2017), we show how exotic quantum dynamics emerges when quantum emitters are spectrally tuned around the middle of the band of a two-dimensional structured reservoir, where we predict the failure of perturbative treatments, anisotropic non-Markovian interactions, and remarkable superradiant and subradiant behavior. In this work, we provide further analysis of that situation, together with a complete analysis for the quantum emitter dynamics in spectral regions different from the center of the band.
We develop a comprehensive theoretical framework that unifies quantum emission dynamics in one-dimensional Lieb lattices, bridging the gap between ideal flat-band coherence and realistic narrow-band dissipation. By coupling an emitter to sublattices with finite flat-band wavefunction overlap, we activate a collective, size-independent interaction fundamentally distinct from dispersive-band processes. Controllably breaking lattice symmetry transforms the flat band into a narrow dispersive band, enabling a continuous crossover from non-Markovian to Markovian dynamics governed by the competition between coupling strength and engineered bandwidth. Crucially, we derive explicit scaling laws that provide a quantitative blueprint for tuning spontaneous emission from coherent trapping to Markovian decay. Our work provides a unified framework that connects idealized flat-band physics to emerging narrow-band platforms such as moireˊ photonic crystals, offering a practical toolkit for interpreting experiments and engineering quantum emission in structured photonic environments.
While non-Markovian dynamics have been extensively studied in the single-excitation limit to predict non-trivial phenomena, this regime remains an idealization. Moving beyond it is essential, as optical nonlinearities and phase-error accumulation in multi-photon processes render the Markovian approximation fragile. In this work, we present a Green's function-based framework for modeling non-Markovian multi-emitter quantum electrodynamics within the two-excitation manifold. The modified Langevin noise (M-LN) formalism is employed for first-principles treatment of dissipative environments, while the emitter-centered mode (ECM) framework ensures computational tractability. Unlike conventional approaches that integrate out the reservoir, we construct a non-Markovian hierarchy of coupled differential equations by explicitly retaining photonic amplitudes. Within the two-excitation hierarchy, the formulation preserves total probability and retains phase information necessary to capture multi-photon interference. As numerical demonstrations, we investigate non-Markovian atom-field interactions in structured semi-infinite waveguide environments. We first consider a homogeneous waveguide as a baseline, observing enhanced Bell-state fidelity in selected configurations. Next, we examine collective decay of symmetric Dicke states in a waveguide with an embedded lossy dielectric slab, revealing selective stabilization and delayed excitation transfer induced by the structured reservoir. Finally, we analyze entanglement dynamics in the same setting, highlighting entanglement sudden birth and oscillatory revivals. In principle, the framework applies to arbitrary electromagnetic environments for which the dyadic Green's function can be obtained numerically, providing a versatile tool for investigating complex non-Markovian multi-photon phenomena beyond the single-excitation limit.
In non-Markovian light-matter interactions, a spectrally structured bath can alter the evolution of a quantum emitter by modifying the vacuum fluctuations experienced by the emitter. This raises the question of how the localization transition and the associated multifractal critical modes induced by a quasiperiodic potential shape the emitter dynamics. We investigate this scenario in the single-excitation sector for a two-level quantum emitter coupled to an Aubry-André-Harper (AAH) photonic lattice. By externally tuning the strength of the quasiperiodic onsite modulation, the lattice is tuned from the extended to the localized regime through a critical point characterized by multifractal modes. Using modal analysis, we show that the quasiperiodic modulation reshapes the local density of states at the coupling site and thereby controls the effective spectral coupling between the emitter and the lattice. The transient dynamics depend strongly on the spatial and spectral overlap between the emitter and the lattice modes: extended modes below the critical modulation generally produce rapid depopulation, whereas critical and localized modes give rise to coherent back-action and persistent Rabi-like oscillations, with particularly pronounced behavior at the critical point. We further identify emitter-photon bound states whose formation is controlled by the quasiperiodic spectral structure of the bath and whose overlap with the initially excited state leads to partial long-time population trapping. These results establish a direct connection between quasiperiodic localization, non-Markovian dynamics, and emitter-photon bound-state formation.