arXiv subjects

Yuangang Deng

Publications and source records attributed to Yuangang Deng.

At least 19 recordsLinked to original sources

arXiv2026

Spin-Exchange-Controlled Nonclassical Light in Cavity Electromagnetically Induced Transparency

Controlling nonclassical light while maintaining a finite cavity response requires selective suppression of unwanted multiphoton excitation. We investigate a ring-cavity system containing two three-level emitters coupled by a coherent spin-exchange interaction, where electromagnetically induced transparency (EIT) provides resonant access to a dark-state polariton. The exchange interaction shifts the polariton resonance while modifying the dressed two-photon excitation pathways. Strong photon antibunching emerges when the one-polariton resonance nearly coincides with a destructive-interference minimum of the second-photon transition amplitude. By jointly tuning the exchange interaction and control-field strength, pronounced photon blockade with a finite intracavity population can be sustained over an extended interaction range. We further show that the relative cavity-coupling phase redistributes optical coupling between symmetric and antisymmetric collective channels with opposite exchange shifts, allowing the photon statistics to switch between antibunching and bunching at fixed exchange strength. This mechanism provides a possible route to tunable nonclassical-light sources based on coherent control of collective excitation pathways.

quant-ph↗

arXiv2026

Path Complementarity Enables Directional Quantum Light in Hybridized Cavity Polaritons

Directional quantum light requires asymmetric photon statistics without sacrificing coherence between propagation paths, a combination that remains difficult to achieve within a single quantum-optical platform. Here we identify a microscopic path-complementarity mechanism in hybridized cavity polaritons that reconciles these two requirements. In a Zeeman-split ring-cavity QED system, cavity backscattering hybridizes the counterpropagating modes, whereas the Zeeman splitting creates spectrally asymmetric excitation channels. Their interplay gives rise, under weak driving, to directional photon blockade coexisting with strong single-photon path entanglement: one input direction exhibits antibunching while the opposite direction is bunched. Remarkably, switching between the two one-photon polariton resonances reverses both the photon-statistical and intensity asymmetries while nearly preserving the path concurrence over a broad parameter regime. Our results establish path complementarity as a general design principle for directional nonclassical light with retained quantum coherence.

quant-ph↗

arXiv2026

Kerr-Filtered Hybrid States from Double-Squeezed Tripartite Interactions

Multipartite interactions provide a unique route to generate hybrid quantum states, yet their intrinsically weak nonlinear coupling limits the controllable manipulation of the resulting correlations. Here we show that cooperative double squeezing and cavity Kerr nonlinearity together enable controllable engineering of Kerr-filtered hybrid states in a tripartite spin-photon-phonon system. Double squeezing exponentially enhances the spin-mediated photon-phonon pair-generation channel, whereas the Kerr interaction selectively reshapes the photonic component while maintaining the underlying tripartite conversion process. This mechanism reconstructs the composition of the hybrid excitation and gives rise to a fourfold phase-space manifold associated with spontaneous $Z_{2}^{(a)}\times Z_{2}^{(b)}$ parity breaking. Our results reveal a strategy for engineering hybrid quantum states by combining interaction amplification with mode-selective nonlinear filtering.

quant-ph↗

arXiv2026

Interaction-enhanced photon blockade and Bell-state protection in microwave-shielded polar molecules

Microwave shielding has recently emerged as a powerful tool for engineering interactions in ultracold polar molecules, yet its potential for controlling cavity quantum electrodynamics remains largely unexplored. Here, we investigate a molecular cavity quantum electrodynamics platform in which two microwave-shielded polar molecules are coupled to a single optical cavity mode and demonstrate that shielding-induced interactions provide a unified mechanism for both photon blockade and Bell-state protection. The anisotropic interaction reshapes the few-excitation spectrum by enhancing its anharmonicity, thereby suppressing multiphoton transitions and improving the single-photon purity by more than three orders of magnitude. The enhanced blockade is accompanied by the emergence of negative longitudinal spin correlations, revealing the interaction-induced suppression of simultaneous molecular excitations. We further show that the photon statistics are highly sensitive to the relative molecular configuration, with positional variations on the scale of the relative zero-point fluctuation substantially modifying the blockade performance. Beyond few-photon nonlinear optics, the same interaction protects an initially prepared molecular Bell state by dispersively decoupling molecular excitations from the lossy cavity mode, thereby suppressing cavity-mediated dissipation and slowing the fidelity decay. Our results establish microwave-shielded interactions as a unified interaction resource for engineering few-photon nonlinearities and protecting quantum states in molecular cavity-QED systems.

cond-mat.quant-gas↗

arXiv2026

Dissipation-selected photon-phonon pair and photon-bundle emission in a tripartite Mollow system

Dissipation is generally regarded as detrimental to nonclassical-state generation, yet whether it can determine which quantum resource is emitted from an open hybrid quantum system remains largely unexplored. Here, we show that the symmetry of bosonic dissipation channels can select and switch quantum-emission pathways in a tripartite Mollow system, where a strongly driven two-level emitter simultaneously couples to cavity photons and motional phonons. In the Mollow regime, higher-order tripartite interactions generate resonant photon-phonon pair excitations, whose emitted quantum states are subsequently selected by dissipation. Under symmetric dissipation, the system produces strongly correlated photon-phonon pairs, enabling both single-pair emission and correlated multipair bundles with pronounced nonclassical correlations. Breaking the dissipation symmetry progressively suppresses the hybrid correlations and dynamically decouples the photonic and phononic degrees of freedom. In the strongly asymmetric regime, long-lived phonons accumulate in highly excited Fock states, while rapidly leaking cavity photons are converted into high-purity single-photon and two-photon bundles. The crossover between these distinct emission regimes is characterized through time-resolved correlation functions, Fock-state distributions, and Wigner quasiprobability distributions. Our results establish dissipation symmetry as a resource for steering quantum emission between hybrid and purely photonic nonclassical states, providing a route toward programmable hybrid quantum emitters and dissipative quantum-state engineering.

quant-ph↗

arXiv2026

Quantum Interference Amplifies Weak Chirality into Giant Quantum Nonreciprocity

Quantum nonreciprocity at few-photon level typically requires strong symmetry breaking, posing significant experimental challenges. Here we demonstrate that phase-controlled quantum interference can amplify weak chirality into giant quantum nonreciprocity. We consider two phase-programmable atoms coupled to a spinning whispering-gallery-mode resonator, where interference dramatically amplifies the effect of weak Fizeau splitting. This mechanism generates pronounced directional asymmetry in photon statistics, featuring bright antibunched emission in one direction and strongly bunched emission in the opposite direction. Remarkably, both correlation and brightness isolations obey phase-controlled power-law scaling with Fizeau splitting, reaching up to 65~dB and 17.3~dB, respectively. Our results establish interference-enhanced weak chirality as a powerful route toward directional nonclassical light sources.

quant-ph↗

arXiv2026

Many-Body Amplified Nonclassical Photon Emission in Cavity-Coupled Atomic Arrays

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.

quant-ph↗

arXiv2026

Deterministic multiphoton bundle emission via interference-interaction control

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.

quant-ph↗

arXiv2026

Dual-mode ground-state cooling in quadratic optomechanical systems: from multistability to general dark-mode suppression

We theoretically investigate a quadratic optomechanical system comprising a single-mode optical cavity linearly coupled to one mechanical resonator and quadratically coupled to a second resonator. By tuning the cavity detuning and optomechanical coupling strengths, we demonstrate the transition from optical bistability to multistability with up to seven steady-state solutions. Notably, simultaneous ground-state cooling of both mechanical resonators occurs on the dynamically stable branch of the nonlinear steady-state solutions, offering new opportunities for combined nonlinear optical and quantum cooling functionalities. Beyond the multistable regime, we systematically study dual-mode ground-state cooling and find that robust simultaneous cooling can be achieved over a broad parameter range, except when the linear and quadratic couplings become comparable, where a dark-mode effect arises. In this case, tuning the second-order optomechanical-induced frequency shifts effectively suppresses dark-mode interference, enabling controllable and simultaneous ground-state cooling. Our results provide a versatile framework for engineering multimode quantum states in optomechanical systems and open new avenues for the development of multifunctional quantum devices, including ultra-sensitive sensors, scalable quantum memories, and integrated quantum networks.

quant-ph↗

arXiv2025

Tunable Single- and Multiphoton Bundles in Cavity-Coupled Atomic Arrays

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.

quant-ph↗

arXiv2025

Dark Superradiance in Cavity-Coupled Polar Molecular Bose-Einstein Condensates

We propose an experimental scheme to realize phase transition from {\it dark superradiance} to conventional superradiance in a microwave cavity coupled to polar molecules. The competition between cavity-mediated infinite-range repulsions and finite-range attractive dipolar interactions stabilizes a variety of exotic quantum phases, including vortex, vortex anti-vortex pairs, and superradiant phase, all emerging without external driving fields. In vortex phase associated with {\it dark superradiance}, cavity remains in vacuum state while profoundly reshaping the condensate's ground-state wave functions. In particular, the spin configuration locally parallel but globally anti-parallel is a direct consequence of competing for two nonlocal interactions. Beyond Dicke paradigm, dipolar dressing of condensate enables access to an unexplored regime of repulsion-dominated superradiance. A Bogoliubov analysis of low-energy excitation spectrum confirms that the condensate remains stable, avoiding roton-maxon induced collapse even in strongly dipolar regime.

cond-mat.quant-gas↗

arXiv2025

Topological Dynamics and Correspondences in Composite Exceptional Rings

The study of unconventional phases and elucidation of correspondences between topological invariants and their intriguing properties are pivotal in topological physics. Here, we investigate a complex exceptional ring (CER), composed of a third-order exceptional ring and multiple Weyl exceptional rings, and establish a direct correspondence between Chern numbers and the distinctive behaviors of these structures. We show that band braiding during quasistatic encircling processes correlates with nontrivial Chern numbers, resulting in triple (double) periodic spectra for topologically nontrivial (trivial) middle bands. Moreover, Chern numbers predict mode transfer during dynamical encircling. Experimental schemes for realizing CER in cold atoms are proposed, emphasizing the crucial role of Chern numbers as both measurable quantity and descriptor of exceptional physics in dissipative systems. This discovery broadens topological classifications in non-Hermitian systems, with promising applications in quantum computing and metrology.

cond-mat.quant-gas↗

arXiv2025

Atom-Molecule Superradiance and Entanglement with Cavity-Mediated Three-Body Interactions

Ultracold atoms coupled to optical cavities offer a powerful platform for studying strongly correlated many-body physics. Here, we propose an experimental scheme for creating biatomic molecules via cavity-enhanced photoassociation from an atomic condensate. This setup realizes long-range three-body interactions mediated by tripartite cavity-atom-molecule coupling. Beyond a critical pump strength, a self-organized square lattice phase for molecular condensate emerges, resulting in hybrid atom-molecule superradiance with spontaneous $U(1)$ symmetry breaking. Distinct from previously observed ultracold bosonic (fermionic) atomic superradiance, our findings demonstrate bosonic enhancement characterized by a cubic scaling of steady-state photon number with total atom number. Additionally, strong photon-matter entanglement is shown to effectively characterize superradiant quantum phase transition. Our findings deepen the understanding of quantum superchemistry and exotic many-body nonequilibrium dynamics in cavity-coupled quantum gases.

cond-mat.quant-gas↗

arXiv2024

$N$-photon bundles emission in high-spin Jaynes-Cummings model

High-spin quantum systems, endowed with rich internal degrees of freedom, constitute a promising platform for manipulating high-quality $n$-photon states. In this study, we explore $n$-photon bundles emission by constructing a high-spin Jaynes-Cummings model (JCM) within a single-mode cavity interacting with a single spin-$3/2$ atom. Our analysis reveals that the $n$-photon dressed state splittings can be significantly enhanced by adjusting the linear Zeeman shift inherent to the internal degrees of freedom in high-spin systems, thereby yielding well-resolved $n$-photon resonance. The markedly enhanced energy-spectrum anharmonicity, stemming from strong nonlinearities, enables the realization of high-quality $n$-photon bundles emission with large steady-state photon numbers, in contrast to conventional spin-1/2 JCM setups. Of particular interest is the realization of an optical multimode transducer capable of transitioning among single-photon blockade, two- to four-photon bundles emission, and photon-induced tunneling by tuning the light-cavity detuning in the presence of both cavity and atomic pump fields. This work unveils significant opportunities for diverse applications in nonclassical all-optical switching and high-quality multiphoton sources, deepening our understanding of creating specialized nonclassical states and fundamental physics in high-spin atom-cavity systems.

cond-mat.quant-gas↗

arXiv2024

Tunable multiphoton bundles emission in a Kerr-type two-photon Jaynes-Cummings model

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.

quant-ph↗

arXiv2024

The synthetic gauge field and exotic vortex phase with spin-orbital-angular-momentum coupling

Ultracold atoms endowed with tunable spin-orbital-angular-momentum coupling (SOAMC) represent a promising avenue for delving into exotic quantum phenomena. Building on recent experimental advancements, we propose the generation of synthetic gauge fields ,and by including exotic vortex phases within spinor Bose-Einstein condensates, employing a combination of a running wave and Laguerre-Gaussian laser fields. We investigate the ground-state characteristics of the SOAMC condensate, revealing the emergence of exotic vortex states with controllable orbital angular momenta. It is shown that the interplay of the SOAMC and conventional spin-linear-momentum coupling induced by the running wave beam leads to the formation of a vortex state exhibiting a phase stripe hosting single multiply quantized singularity. The phase of the ground state will undergo the phase transition corresponding to the breaking of rotational symmetry while preserving the mirror symmetry. Importantly, the observed density distribution of the ground-state wavefunction, exhibiting broken rotational symmetry, can be well characterized by the synthetic magnetic field generated through light interaction with the dressed spin state. Our findings pave the way for further exploration into the rotational properties of stable exotic vortices with higher orbital angular momenta against splitting in the presence of synthetic gauge fields in ultracold quantum gases.

cond-mat.quant-gas↗

arXiv2024

Self-Ordered Supersolid in Spinor Condensates with Cavity-Mediated Spin-Momentum-Mixing Interactions

Ultracold atoms with cavity-mediated long-range interactions offer a promising platform for investing novel quantum phenomena. Exploiting recent experimental advancements, we propose an experimental scheme to create self-ordered supersolid in spin-$1/2$ condensates confined within an optical cavity. The interplay of cavity and pump fields gives rise to supersolid square and plane wave phases, comprehensively described by the two-component Tavis-Cummings model. We show that the self-ordered supersolid phase exhibits an undamped gapless Goldstone mode over a wide parameter range. This proposal, achievable with current experimental setups utilizing identical laser configurations, is in contrast to the realization of checkerboard supersolidity, which hinges on constructing a $U(1)$ symmetry by utilizing two ${\cal Z}_2$ symmetries with precisely matched atom-cavity coupling in multimode resonators. By employing the superradiant photon-exchange process, we realize for the first time cavity-mediated spin-momentum-mixing interactions between highly correlated spin and momentum modes, analogous to that observed spin-mixing in spin-1 condensates. Our scheme provides a unique platform for realizing spin-momentum squeezing and spatially distributed multipartite entanglement.

cond-mat.quant-gas↗

arXiv2023

Unveiling Vacuum Fluctuations and Nonclassical States with Cavity-Enhanced Tripartite Interactions

Enhancing and tailoring light-matter interactions offer remarkable nonlinear resources with wide-ranging applications in various scientific disciplines. In this study, we investigate the construction of strong and deterministic tripartite `beamsplitter' (`squeeze') interactions by utilizing cavity-enhanced nonlinear anti-Stokes (Stokes) scattering within the spin-photon-phonon degrees of freedom. We explore the exotic dynamical and steady-state properties associated with the confined motion of a single atom within a high-finesse optical cavity. Notably, we demonstrate the direct extraction of vacuum fluctuations of photons and phonons, which are inherent in Heisenberg's uncertainty principle, without requiring any free parameters. Moreover, our approach enables the realization of high-quality single-quanta sources with large average photon (phonon) occupancies. The underlying physical mechanisms responsible for generating nonclassical quantum emitters are attributed to decay-enhanced single-quanta blockade and the utilization of long-lived motional phonons, resulting in strong nonlinearity. This work unveils significant opportunities for studying hitherto unexplored physical phenomena and provides novel perspectives on fundamental physics dominated by strong tripartite interactions.

quant-ph↗