A new method enables collective emission from solid-state emitters, even with substantial inhomogeneous broadening, a result previously thought unachievable. Uri Israeli and colleagues at Hebrew University of Jerusalem, in collaboration with Racah Institute of Physics, observed this phenomenon using subwavelength arrays of silicon-vacancy centres in diamond. The findings reveal that resonance shifts, modified decay rates, and directional coherent emission persist when inhomogeneous broadening exceeds the natural linewidth by two orders of magnitude. We achieve this by creating ‘superatoms’ via high-density silicon ion implantation, which enables frequency matching and enhances the collective response. These observations represent a key step towards realising naturally integrated quantum-emitter metasurfaces in solid-state systems and open avenues for enhanced atom-photon interaction

Collective emission enabled in disordered diamond via probabilistic frequency matching

Collective emission from silicon-vacancy centres in diamond has been achieved despite substantial internal disorder, with inhomogeneous broadening exceeding the natural linewidth by two orders of magnitude, a previously insurmountable barrier. A sharp advance has been made as collective effects were long thought to be suppressed when inhomogeneity surpasses 10GHz, effectively silencing the coordinated light emission needed for quantum technologies. Dr. Elke Zinner and colleagues overcame this limitation by creating “superatoms” through high-density silicon ion implantation, probabilistically matching the frequencies of individual silicon-vacancy centres within each array site. Inhomogeneous broadening arises from variations in the local environment surrounding each silicon-vacancy centre, causing slight shifts in their emission wavelengths; this is a significant challenge in solid-state quantum emitters as it dephases the collective emission necessary for quantum phenomena.

High densities of silicon ions were implanted into each array site, creating ensembles comprised of tens of SiV centres confined within a 30-nanometer space. This high density is crucial, as it increases the probability of finding multiple SiV centres with sufficiently close resonant frequencies to interact collectively. These superatoms probabilistically achieve frequency matching, enhancing the collective response and building up coherence even with strong inhomogeneity; the arrays themselves are spaced approximately 250 nanometers apart, roughly 0.7λ where λ is the resonant wavelength within the diamond. This spacing is carefully chosen to balance the need for strong coupling between superatoms and to avoid unwanted interference effects. Directional emission analysis revealed resonance shifts and modified decay rates, directly determining emission directionality and mirroring theoretical predictions of a parabolic dispersion relation near zero momentum. The observed parabolic dispersion relation is a hallmark of collective emission, indicating that the emitted photons are correlated and propagate in a coherent manner.

Theoretical modelling supports these observations, explaining how collective effects are preserved even with such pronounced inhomogeneity, opening possibilities for naturally integrated quantum-emitter metasurfaces. The models demonstrate that the high density of emitters within each superatom effectively narrows the apparent linewidth, allowing for collective behaviour despite the overall inhomogeneous broadening. While the focus remains on demonstrating the possibility of collective emission under these conditions, rather than optimising it for specific performance metrics, quantifying the degree of enhancement achieved through this approach is a necessary next step. Future work will involve detailed comparison of performance metrics against theoretical limits and optimisation of the system for specific applications, including exploration of integration with nanophotonic environments. Integration with nanophotonic structures could further enhance light extraction efficiency and enable the creation of compact quantum devices.

Collective emission from arrays of silicon-vacancy centres in diamond, solid-state light emitters exhibiting inhomogeneous broadening exceeding the natural linewidth by two orders of magnitude, has been observed. This observation challenges the previously held assumption that such strong disorder would suppress the photon-mediated interactions necessary for collective behaviour. Prior research on collective emission largely focused on homogeneous systems, such as ultracold atom arrays, offering precise control over emitter properties unlike the inherent disorder present in solid-state materials. Ultracold atoms, held at extremely low temperatures, exhibit negligible thermal motion and minimal variations in their properties, allowing for precise control and observation of collective phenomena.

Previous work demonstrated switchable atomic mirrors and superradiance bursts utilising arrays of rubidium atoms, all employing homogeneous atomic systems. These experiments served as a proof-of-concept for collective emission but were limited by the complexity and cost of maintaining ultracold atom arrays. Solid-state emitter arrays are now considered a potential platform for quantum-emitter metasurfaces, offering advantages in terms of scalability and room-temperature operation, though limitations concerning scalability or fabrication beyond initial demonstrations remain unaddressed, as do comparisons to other solid-state emitters or the efficiency of the collective emission. The development of scalable fabrication techniques is crucial for realising practical quantum devices based on solid-state emitters. Earlier experiments with rubidium atoms showed switchable atomic mirrors and superradiance bursts, but these relied on homogeneous atomic systems.

Recent observations reveal collective emission from subwavelength arrays of silicon-vacancy centres in diamond, solid-state emitters exhibiting substantial inhomogeneous broadening. This work contrasts with previous studies, which focused on the more challenging scenario of solid-state emitters. Dr. Zinner and colleagues acknowledge that quantifying the degree of enhancement achieved remains a future goal. We create ‘superatoms’ from silicon-vacancy centres, defects within diamond that emit light, and this has enabled scientists to observe collective emission despite significant internal disorder. Silicon-vacancy centres are formed when a carbon atom in the diamond lattice is replaced by a silicon atom, creating a defect with unique optical properties. This achievement overcomes a major obstacle preventing the development of solid-state quantum technologies, where variations in emitted light frequency, known as inhomogeneous broadening, typically suppress the necessary interactions. Demonstrating coherent light emission under these conditions establishes a pathway towards naturally integrated quantum-emitter metasurfaces, paving the way for advanced nanophotonic devices, and prompts investigation into optimising these arrays and exploring their potential for complex quantum systems, such as enhanced sensors and communication networks. Potential applications include quantum key distribution, single-photon sources, and high-precision sensing.

The research demonstrated collective emission from closely-packed silicon-vacancy centres in diamond, despite these solid-state emitters exhibiting significant variations in emitted light frequency. This is important because such variations typically hinder the strong light-matter interactions needed for quantum technologies. By creating ‘superatoms’, local groupings of these defects, researchers observed resonance shifts, modified decay rates and directional coherent emission. The authors suggest further work will focus on optimising these arrays and exploring their potential for more complex quantum systems.

👉 More information
🗞 Collective emission of subwavelengths atom-like emitter arrays in the presence of inhomogeneous broadening
🧠 ArXiv: https://arxiv.org/abs/2606.07458

More like this