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.
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 propose an experimentally accessible scheme for realizing tunable nonclassical light in cavity-coupled reconfigurable atomic arrays. By coherently controlling the collective interference phase, the system switches from single-photon blockade to high-purity multiphoton bundle emission, unveiling a hierarchical structure of photon correlations dictated by atom-number parity and cavity detuning. The scaling of photon population identifies the transition between superradiant and subradiant regimes, while parity- and phase-dependent spin correlations elucidate the microscopic interference processes enabling coherent multiphoton generation. This work establishes a unified framework connecting cooperative atomic interactions to controllable nonclassical photon statistics and introduces a distinct interference-enabled mechanism that provides a practical route toward high-fidelity multiphoton sources in scalable cavity QEDs.
High-quality special nonclassical states beyond the strong single atom-cavity coupling regime are fundamental elements in quantum information science. Here, we study strong single-photon blockade to two-photon bundles emission in a single spin-1 atom coupled to an optical cavity by constructing a spin-1 Jaynes–Cummings model (JCM). By tuning the quadratic Zeeman shift, the energy-spectrum anharmonicity can be significantly enhanced, leading to a remarkable increase in the dressed-state splitting of the well-resolved n-photon resonance. The mechanism, which benefits from the internal degrees of freedom in high-spin systems, compensates for the strong coupling condition required by the multi-photon blockade, thereby facilitating the experimental feasibility of engineering special nonclassical states beyond the strong-coupling limit. It is shown that the photon emission from the spin-1 JCM demonstrates high-quality single photon and two-photon bundles with large steady-state photon numbers in the cavity-driven and atom-pump cases, respectively. In particular, compared to the two-level two-photon JCM, the antibunching amplitude of the three-order correlation function for two-photon bundles in the spin-1 JCM is enhanced by 3 orders of magnitude. More interestingly, a multimode transducer, enabling a transition from strong single-photon blockade to two-photon bundles and super-Poissonian photon emission, is achieved and highly controllable by the light-cavity detuning in the presence of both atom and cavity driven fields. This study based on the high-spin JCM broadens the scope of engineering special nonclassical quantum states beyond the standard two-level JCM. Our proposal not only opens up a new avenue for generating high-quality n-photon sources but also provides versatile applications in quantum networks and metrology.
We propose a component-selective scheme for improving two-photon sources in a cavity-coupled two-atom system, where a single cavity mode interacts with two two-level atoms driven by phase-controlled classical fields of the same frequency. By controlling the atomic detunings and driving phase, the system can be tailored toward optimized cavity-field two-photon blockade or strongly correlated fluorescence photon-pair emission. When the two-cavity-photon component is enhanced, the cavity field exhibits optimized two-photon blockade with simultaneous suppression of unwanted one- and three-photon components at a comparable two-photon population. In another parameter regime, strongly correlated fluorescence photon pairs can also be generated from the two atoms by selecting the double-atomic-excitation component in the same two-excitation manifold. This approach provides a route toward high-quality and versatile two-photon sources, with potential applications in few-photon quantum optics and quantum information processing.
A recent experiment [H. S. Han et al., Phys. Rev. Lett. 127, 073604 (2021); see also accompanying online supplemental material] shows that when a three-level
V-type atom with two closely lying upper states interacts with the same vacuum radiation field, its excited states enable vacuum-induced coupling (VIC) owing to the quantum interference between the spontaneous emission pathways. Here, we propose a feasible scheme for phase-engineered photon correlations in the presence of the VIC in an optical nanofiber (ONF) cavity quantum electrodynamics (QED) system. Specifically, we show that a phase-dependent strong photon antibunching with high brightness can be generated in the weak-coupling regime of light-atom interactions. This occurs because of the VIC, leading to both the destructive quantum interference between the different pathways for two-photon excitation and the total closed-loop coupling phase. Different types of purely quantum correlations, such as single- and two-photon blockades, can occur by properly tuning the total closed-loop coupling phase adhering on the VIC, and the switch from photon blockade to photon induced tunneling is revealed as well. On the other hand, the strong photon antibunching can be achieved in a broad driving frequency range, which relaxes the requirement for the driving frequency in the ONF cavity QED system. In addition, we compare the analytical and numerical results of the second- and third-order intensity correlation functions, and they are in good agreement. The present study may provide an alternative route to manipulate the few-photon states and have potential applications in single-photon sources and quantum communications.