From superradiance to collective EIT in three-level ensembles
Instituto de Física de São Carlos, Universidade de São Paulo（圣卡洛斯物理研究所，圣保罗大学）；Instituto de Ciências e Engenharia, Universidade Estadual Paulista - Câmpus de Itapeva（科学与工程学院，圣保罗州立大学-伊塔佩瓦校区）；Instituto de Física, Universidade Federal de Goiás（物理研究所，戈亚斯联邦大学）
Hugo Sanchez, Luis F. A. da Silva, Mickel A. Ponte, Miled H. Y. Moussa, Norton G. de Almeida
我们研究了在Dicke极限下三能级集合的集体动力学，揭示了超辐射发射与电磁诱导透明（EIT）之间的统一联系。我们的结果表明，瞬时超辐射爆发表现出预期的峰值强度标度$ I_{\max}\!\sim\! N^2 $，具有一个普遍的有限大小修正$ |ξ(N)-2|\!\sim\! 1/\ln N $，它支配了现实集合中 apparent 标度指数。在稳态情况下，集体展宽修改了EIT响应：尽管它通常增强吸收，但反直觉地增加了群速度，导致相对标度$ v_g\!\propto\! N^2 $，即使$ v_g\!\ll\! c $。这种效应表明，合作相互作用从根本上限制了在密集介质中可实现的慢光延迟。为了实现这些结果，我们推导了一个代表原子主方程，该方程定量地重现了超辐射和EIT区域，与精确的对称子空间动力学高度一致，并正确地纳入了集体反馈和$ N $依赖的展宽。这个统一的框架连接了瞬时超辐射发射和稳态量子干涉，对慢光、量子存储和精密计量有直接的影响。
英文摘要：
We investigate the collective dynamics of a three-level ensemble under the Dicke limit, revealing a unified connection between superradiant emission and electromagnetically induced transparency (EIT). Our results show that the transient superradiant burst exhibits the expected peak intensity scaling $I_{\max}\!\sim\! N^2$, with a universal finite-size correction $|ξ(N)-2|\!\sim\! 1/\ln N$ that governs the apparent scaling exponent in realistic ensembles. In the stationary regime, collective broadening modifies the EIT response: although it typically enhances absorption, it counterintuitively increases the group velocity, leading to a relative scaling $v_g\!\propto\! N^2$, even while $v_g\!\ll\! c$. This effect suggests that cooperative interactions fundamentally limit the achievable slow-light delay in dense media. To achieve these results, we derive a representative-atom master equation that quantitatively reproduces both the superradiant and EIT regimes, in excellent agreement with the exact symmetric-subspace dynamics and correctly incorporating collective feedback and $N$-dependent broadening. This unified framework bridges transient superradiant emission and steady-state quantum interference, with direct implications for slow light, quantum memories, and precision metrology.
Absence of Entanglement Growth in Dicke Superradiance
Max Planck Institute for the Science of Light（马克斯·普朗克光科学研究所）；Friedrich-Alexander-Universität Erlangen-Nürnberg（埃尔朗根-纽伦堡弗里德里希·亚历山大大学）；TU Darmstadt, Institute for Applied Physics（达姆施塔特工业大学应用物理研究所）
Collective effects in the interaction of light with ensembles of identical scatterers play an important role in many fields of physics. However, often the term ``identical'' is not accurate due to the presence of hyperfine fields which induce inhomogeneous transition shifts and splittings. Here we develop a formalism based on the Green function method to model the linear response of such inhomogeneous ensembles in one-dimensional waveguides. We obtain a compact formula for the collective spectrum, which exhibits deviations from the uniform frequency shift and broadening expected of two level s…
Non-Markovian super-superradiance in a linear chain of up to 100 qubits
我们研究了耦合到一维波导的100个量子比特的线性链中的集体激发自发发射的非马尔可夫增强效应。我们发现，对于临界分离的量子比特，系统表现出超超辐射（SSR）行为导致集体衰变强于通常的迪克超辐射。在这里，时间延迟的相干量子反馈效应是在通常的迪克超辐射效应之上发挥作用的。我们发现SSR的衰减率随着量子比特数$N$的增加而线性缩放，使得$Γ_{\rm SSR} \sim 2.277 N γ_0$，其中$γ_0$是一维波导的单发射器衰减率，而不是Dicke超辐射的$Γ_{\rm Dicke}\sim N γ_0$。SSR的衰减速率可以通过量子比特的间隔距离来调节，因此可以应用于量子技术。
Symbolic Quantum-Trajectory Method for Multichannel Dicke Superradiance
University of Innsbruck（因斯布鲁克大学）；Harvard University（哈佛大学）；TU Darmstadt（达姆施塔特工业大学）；Max Planck Institute for the Science of Light（马克斯·普朗克光科学研究所）；Friedrich-Alexander Universität Erlangen-Nürnberg (FAU)（埃尔朗根-纽伦堡弗里德里希·亚历山大大学）
Intriguing collective spontaneous cascade emissions have recently been realized. In despite of much success, a depth understanding of the complexity is still lacking. With this motivation, a new simple cascade superradiance model is developed in this work. The existing model of identical two-level atoms is reexamined with a new insight. Temporal evolutions of average time delays and the fluctuations are introduced and the superradiance time delays are obtained in four different ways. These formulations allow to extend the two-level model to a cascade three-level model. The correlated two-mode …
Recently, it has been suggested that the collective radiative decay of two point-like quantum emitters coupled to a waveguide, separated by a distance comparable to the coherence length of a spontaneously emitted photon, leads to an apparent $^{\prime}$superradiance paradox$^{\prime}$ by which one cannot decide whether independent or collective emission occurs. The resolution of the paradox stems from the strong non-Markovian dynamics arising from the delayed field-mediated atom interaction. Here we suggest an integrated optics platform to emulate the superradiance paradox, based on photon esc…
Scaling theory of decoherence in Dicke superradiance
TU Darmstadt（达姆施塔特工业大学）；Friedrich-Alexander-Universität Erlangen-Nürnberg（埃尔朗根-纽伦堡大学）；Max Planck Institute for the Science of Light（马克斯·普朗克光科学研究所）；CNRS and Université de Strasbourg（法国国家科学研究中心与斯特拉斯堡大学）
Collective emission behavior is usually described by the decay dynamics of the completely symmetric Dicke states. To study a more realistic scenario, we investigate alternative initial states inducing a more complex time evolution. Superposition states of the fully inverted Dicke state and the Dicke ground state with unequal mutual weights are studied as examples as well as superradiance stemming from atoms in clusters separated by more than one wavelength. The Monte Carlo wave function method serves as framework to study the dynamics of quantum states, which is determined by quantum jumps on …
超辐射，增强集体发射的光从一个相干系综的量子系统，已被典型地研究在原子系综。在这项工作中，我们研究了谐振子相干系综的能量增强发射。我们表明，应该有可能观察到谐振子超辐射在各种物理平台，如波导阵列集成光子学和谐振器阵列电路QED。我们发现一般条件指定时，发射是超辐射和次辐射，并发现超辐射，次辐射和暗态的多模压缩相干态和高度纠缠的多模Fock态的形式。计算了多模Fock态、压缩态、相干态和热态等一系列初始态的强度、双模关联和衰变后俘获在系统中的量子分数。为了探索这些效应，Law和Eberly方案[C. K. Law和J. H. Eberly，Phys. Rev. Lett. 76，1055（1996）]的方法，并将其推广到在电路QED中制备高纠缠多模Fock态。
Dicke superradiance in degenerate quantum matter: interplay of exchange statistics and spatial confinement
Friedrich-Alexander Universität Erlangen-Nürnberg (FAU)（埃尔朗根-纽伦堡弗里德里希·亚历山大大学）；Max Planck Institute for the Science of Light（马克斯·普朗克光科学研究所）；TU Darmstadt（达姆施塔特工业大学）
We study quantitatively the breakdown of the rotating-wave approximation when calculating collective light emission by quantum emitters, in particular in the weak-excitation limit. Our starting point is a known multiple-scattering formalism where the full light-matter interaction leads to induced inter-emitter interactions described by the classical Green function of inhomogeneous dielectric media. When making the RWA in the light-matter interaction, however, these induced interactions differ from the classical Green function, and for free space we find a reduction of the interatomic interacti…
An ensemble of excited atoms can synchronize emission of light collectively in a process known as superradiance when its characteristic size is smaller than the wavelength of emitted photons. The underlying superradiance depends strongly on electromagnetic (photon) fields surrounding the atomic ensemble. High mode densities of microwave photons from $300\,$K blackbody radiation (BBR) significantly enhance decay rates of Rydberg states to neighbouring states, enabling superradiance that is not possible with bare vacuum induced spontaneous decay. Here we report observations of the superradiance …
Max Planck Institute of Quantum Optics（马克斯·普朗克量子光学研究所）；ICFO—Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology（ICFO-光子科学研究所，巴塞罗那科学技术研究院）；Department of Mathematical Sciences, University of Copenhagen（哥本哈根大学数学科学系）；Department of Physics, University of Basel（巴塞尔大学物理系）；Google Quantum AI（谷歌量子人工智能）
Multiple emitters coherently interacting with an electromagnetic mode give rise to collective effects such as correlated decay and coherent exchange interaction, depending on the separation of the emitters. By diagonalizing the effective non-Hermitian many-body Hamiltonian we reveal the complex-valued eigenvalue spectrum encoding the decay and interaction characteristics. We show that there are significant differences in the emerging effects for an array of interacting anharmonic oscillators compared to those of two-level systems and harmonic oscillators. The bosonic decay rate of the most sup…
We study a system of two distant quantum emitters coupled via a one-dimensional waveguide where the electromagnetic field has a direction-dependent velocity. As a consequence, the onset of collective emission is non-simultaneous and, for appropriate parameters, while one of the emitters exhibits superradiance the other can be subradiant. Interference effects enable the system to radiate in a preferential direction depending on the atomic state and the field propagation phases. We characterize such directional emission as a function of various parameters, delineating the conditions for optimal …
