The generation of high-performance nonclassical light remains a cornerstone of quantum technologies, yet faces a fundamental trade-off between emission purity and brightness. Here, we demonstrate that cavity-mediated many-body spin-exchange interactions provide a route to overcome this constraint by collectively amplifying spectral anharmonicity. In a cavity-coupled atomic array with a programmable relative phase
φ, the resulting interference-interaction mechanism reshapes the dressed-state manifold and enables deterministic switching between distinct quantum emission regimes. For
φ=0, constructive interference yields high-purity single-photon emission with antibunching improved by four orders of magnitude while preserving strong photon flux. Conversely, for
φ=π, destructive interference creates a dark single-photon manifold, resonantly activating two-photon processes to produce bright and pure photon-pair bundles. Our work establishes interference-engineered many-body interactions as a scalable mechanism for on-demand quantum light generation and open a new avenue for harnessing collective many-body physics in quantum photonics.
The controlled generation of nonclassical light beyond single photons remains a central challenge in quantum optics, due to the difficulty of enhancing multiphoton processes while suppressing lower-order excitations. Here we propose an interference-interaction-engineered scheme for programmable few-photon emission in a cavity-QED system of three atoms coupled to orthogonal cavity modes. By adiabatically eliminating an auxiliary Fabry-Pérot cavity, we generate a tunable cavity-mediated spin-exchange interaction
χ, which, combined with a controllable geometric phase
φ, reshapes the many-body dressed-state spectrum. This interplay enables selective addressing of excitation manifolds (
N=1,2,3), establishing a direct mapping between excitation structure and photon-emission channels. For
φ=0, constructive interference enhances the spectral anharmonicity of low-excitation manifolds, yielding tunable single- and two-photon emission associated with the
N=1 and
N=2 manifolds. In contrast, for
φ=2π/3, destructive interference suppresses lower-order excitation pathways and activates a resonant three-photon channel originating from the
N=3 manifold. Importantly, the cavity-mediated interaction
χ further enhances spectral separation between manifolds, enabling a substantial improvement in multiphoton purity while maintaining a sizable photon population. We demonstrate a three-order-of-magnitude enhancement in two-photon purity and more than two orders of magnitude improvement in three-photon emission. Our results establish a unified interference-interaction framework in which effective optical nonlinearities can be programmably engineered through phase and interaction, providing a scalable route toward high-purity multiphoton sources and programmable quantum photonic devices.
We present a study on manipulation and enhancement of multiphoton bundles emission under a moderate atom-cavity coupling, by constructing a two-photon Jaynes-Cummings model integrated with Kerr nonlinearity in a single atom-cavity system. We show that the vacuum-Rabi splittings for the n th dressed states can be significantly enhanced by Kerr interaction. This remarkable enhancement in energy-spectrum anharmonicity with the well-resolved multiphoton resonance facilitates the generation of special nonclassical states beyond the strong-coupling limit in the experiment. In particular, both two- and three-photon blockades are observed with adjusting the amplitude of the cavity-driving or atom-pump fields. Moreover, we discover that transitions between two- and three-photon bundles can be achieved through tuning the atom-cavity detuning or Kerr nonlinearity. It further showcases the three-photon blockade is substantially strengthened when both the cavity and atomic fields are jointly driven. Our proposal unveils a pathway for realizing highly controllable nonclassical states and quantum devices with combining two-photon Jaynes-Cummings interactions and Kerr nonlinearity, which may pave the way for versatile applications in quantum information science, e.g., all-optical switches and transistors. Published by the American Physical Society 2024
When multiple quantum emitters couple to a common electromagnetic environment, interference in their collective radiative dynamics gives rise to superradiance and subradiance. In regimes where coherent interactions and collective dissipation compete, the microscopic many-body dynamics and quantum correlations among the emitters that underlie superradiance and subradiance are theoretically challenging and remain experimentally elusive, even though collective emission has been observed in many physical systems. Here, we realize a superconducting qubit array coupled to a common microwave waveguide that mediates collective dissipation, with simultaneous access to coherent interactions and microscopic measurements of many-body dynamics. Engineered qubit-waveguide couplings with tunable amplitude and phase enable control of collective interference and the resulting super- and subradiant states. Leveraging site-resolved control and readout, we directly observe the microscopic decay dynamics of multi-qubit states across different excitation manifolds and track the evolution of populations and tunable quantum correlations. We reveal collective decay in regimes beyond the ideal Dicke model, where strong qubit-qubit interactions stabilize superradiance and subradiance against local dephasing and reshape decay pathways through spatially and spectrally structured many-body eigenstates. Our results establish a flexible platform for exploring collective phenomena in many-body quantum optics and driven-dissipative approaches to robust quantum information processing.
Abstract The generation of nonclassical light with strong photon antibunching and appreciable brightness remains an important goal in quantum technologies. Here, we demonstrate that cavity-mediated spin-exchange interactions provide a route to overcome this constraint by amplifying spectral anharmonicity. In a two-emitter cavity-QED system with a controllable relative phase φ , the resulting interference-interaction mechanism reshapes the dressed-state manifold and enables switching between distinct quantum emission regimes. For φ = 0, constructive interference yields highquality single-photon emission with near-perfect antibunching, suppressing g 1 (2) (0) by more than three orders of magnitude while maintaining a substantial intracavity photon population. Conversely, for φ = π , destructive interference suppresses direct single-photon excitation and selectively enhances two-photon excitation, producing signatures of correlated two-photon emission with appreciable intracavity photon populations and suppressed higher-order excitations. Our work establishes interference-engineered interactions as a mechanism for the controllable selection of single-photon and photon-pair emission, opening new opportunities for programmable nonclassical light sources and quantum photonic applications.
High-purity and bright single-photon sources are important for quantum information processing and precision measurement. We propose a collectively enhanced universal photon-blockade scheme in a multi-emitter two-photon Tavis--Cummings system. Independent coherent drives of the cavity and collective emitter enable destructive interference between two-photon excitation pathways, while collective coupling supplies level anharmonicity. Full-quantum master-equation simulations, the Holstein--Primakoff approximation, and a non-Hermitian probability-amplitude analysis yield the optimal conditions: cavity resonance together with phase and amplitude matching. Compared with a purely collective blockade, the proposed scheme lowers
g(2)(0), and essentially preserves the single-photon population. As the emitter number
N increases, the optimal point remains at
Δc=0, while the minimum correlation follows
gmin(2)(0)∝N−2. By contrast, unconventional photon blockade shifts away from resonance as
N increases, limiting its purity improvement and brightness. In the weak-drive regime, universal blockade obeys
g(2)(0)∝εa2, owing to a higher-order bypass through the three-excitation manifold. The drive strength therefore provides an additional purity--brightness control, although the interference mechanism makes the scheme more sensitive to dissipation-rate mismatch. Our results establish a scalable route to bright, high-purity, and tunable single-photon emission in multi-emitter cavity-QED systems.