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Machines that simultaneously process and store multistate data at one and the same location can provide a new class of fast, powerful and efficient general-purpose computers. We demonstrate the central element of an all-optical calculator, a photonic abacus, which provides multistate compute-and-store operation by integrating functional phase-change materials with nanophotonic chips. With picosecond optical pulses we perform the fundamental arithmetic operations of addition, subtraction, multiplication, and division, including a carryover into multiple cells. This basic processing unit is embedded into a scalable phase-change photonic network and addressed optically through a two-pulse random access scheme. Our framework provides first steps towards light-based non-von Neumann arithmetic. Computing approaches in the optical domain would allow for ultra-fast signaling and ultra-high bandwidth capabilities. Here, Feldmann et al. demonstrate a photonic abacus, which provides multistate compute-and store operation by integrating phase-change materials with nanophotonic chips.

Strongly interacting atom-cavity systems within a network with many nodes constitute a possible realization for a quantum internet which allows for quantum communication and computation on the same platform. To implement such large-scale quantum networks, nanophotonic resonators are promising candidates because they can be scalably fabricated and interconnected with waveguides and optical fibers. By integrating arrays of ring resonators into a vapor cell we show that thermal rubidium atoms above room temperature can be coupled to photonic cavities as building blocks for chip-scale hybrid circuits. Although strong coupling is not yet achieved in this first realization, our approach provides a key step towards miniaturization and scalability of atom-cavity systems.

The on-chip integration of quantum light sources and nonlinear elements poses a serious challenge to the development of a scalable photonic platform for quantum information and communication. In this work we demonstrate the potential of a novel hybrid technology which combines single organic molecules as quantum emitters and dielectric chips, consisting of ridge waveguides and grating far-field couplers. Dibenzoterrylene molecules in thin anthracene crystals exhibit long-term photostability, easy fabrication methods, almost unitary quantum yield and life-time limited emission at cryogenic temperatures. We couple such single emitters to silicon nitride ridge waveguide with a coupling efficiency of up to 42+/-2 %, considering both propagation directions. The platform is devised to support both on-chip and free-space single photon processing.

Urbanization and built environment significantly impact resource consumption, posing sustainability challenges, especially regionally, due to bulk material dominance. Circular practices, like closing, slowing, and narrowing offer solutions. However, effective circularity management requires understanding built environment material stock comprehensively. Material cadastres model city and regional materiality using typology approaches and GIS Modelling, offering insights into circularity potential and supporting strategic circular city management. Conversely, urban planning digitalization introduced City Information Modelling, linking GIS for urban structure mapping with Building Information Modelling systems for digital building integration and thus support urban planning. Yet, empirically, materiality and circularity issues lack systematic and comprehensive integration in such approaches. To this end, this paper discusses the potential of developing digital material cadastre concepts towards materiality-based urban information modelling using case study results that reveal strengths and limitations of existing cadastre concepts. We present a methodological overview covering a general approach to built environment material cadastres and the main components of the underlying bottom up Material Flow approach: material composition indicators and GIS based building stock modelling and a dynamization approach. To discuss circularity potentials of the built environment in a larger urban regional development context, we furthermore designed material cadastres for two case study cities and calculated exemplary circularity potentials for closing, slowing and narrowing approaches. The findings and drafted conclusions were then reflected with urban planning and development actors in workshops and group discussions. As a result, we present consolidated propositions with respect to bridging the methodological gap between strategic and operational materiality informed urban and regional planning in the transition of the built environment towards circularity.

Hybrid quantum photonics combines classical photonics with quantum emitters in a postprocessing step. It facilitates to link ideal quantum light sources to optimized photonic platforms. Optical cavities enable to harness the Purcell-effect boosting the device efficiency. Here, we postprocess a free-standing, crossed-waveguide photonic crystal cavity based on Si with SiV center in nanodiamonds. We develop a routine that optimizes the overlap with the cavity electric field utilizing atomic force microscope (AFM) nanomanipulation to attain control of spatial and dipole alignment. Temperature tuning further gives access to the spectral emitter-cavity overlap. After a few optimization cycles, we resolve the fine-structure of individual SiV centers and achieve a Purcell enhancement of more than 4 on individual optical transitions, meaning that four out of five spontaneously emitted photons are channeled into the photonic device. Our work opens up new avenues to construct efficient quantum photonic devices.

The built environment is the cause of most of the material flows in the anthroposphere and the biggest material storage: Over 90 % of the anthropogenic stock stored in durable goods can be found in the built environment, with non-metallic minerals being the main contributor. In Germany, most of the materials that leave the stock due to demolition or renovation are recovered. In Saxony, a German state, the recovery rate is nearly 99 % but only 55% of mineral construction and demolition waste is recycled. There is still substantial potential for closing recycling loops. This requires the combined effort of all those actors that influence these material flows - from the investor and constructor of the single building to those responsible for waste management at municipal level and the waste disposal and construction materials industry. However, the information currently available is insufficient to support an effective urban mining. This will be encountered by an ongoing research project that aims to enhance existing informational instruments regarding construction related material flows in the built environment. The project follows a dualistic research approach considering informational instruments at (1) individual building level and (2) at regional level. The objective of the paper is to present an approach on how material inventories can be better aligned with practical information needs. After introducing the overall concept and methodology as well as describing the process of analysing the current state of information flows, first results considering the structure of material in- and outputs and the needs for information of different actors are presented.

Hybrid quantum photonics combines classical photonics with quantum emitters in a postprocessing step. It facilitates to link ideal quantum light sources to optimized photonic platforms. Optical cavities enable to harness the Purcell-effect boosting the device efficiency. Here, we postprocess a free-standing, crossed-waveguide photonic crystal cavity based on Si 3 N 4 with SiV − center in nanodiamonds. We develop a routine that optimizes the overlap with the cavity electric field utilizing atomic force microscope (AFM) nanomanipulation to attain control of spatial and dipole alignment. Temperature tuning further gives access to the spectral emitter-cavity overlap. After a few optimization cycles, we resolve the fine-structure of individual SiV − centers and achieve a Purcell enhancement of more than 4 on individual optical transitions, meaning that four out of five spontaneously emitted photons are channeled into the photonic device. Our work opens up new avenues to construct efficient quantum photonic devices.

Spin-based quantum photonics promise to realize distributed quantum computing and quantum networks. The performance depends on efficient entanglement distribution, where the efficiency can be boosted by means of cavity quantum electrodynamics. The central challenge is the development of compact devices with large spin-photon coupling rates and high operation bandwidth. Photonic crystal cavities comprise strong field confinement but put high demands on accurate positioning of an atomic system in the mode field maximum. Color center in diamond, and in particular the negatively-charged Silicon-Vacancy center, emerged as a promising atom-like systems. Large spectral stability and access to long-lived, nuclear spin memories enabled elementary demonstrations of quantum network nodes including memory-enhanced quantum communication. In a hybrid approach, we deterministically place SiV\\(^-\\)-containing nanodiamonds inside one hole of a one-dimensional, free-standing, Si\\(_3\\)N\\(_4\\)-based photonic crystal cavity and coherently couple individual optical transitions to the cavity mode. We optimize the light-matter coupling by utilizing two-mode composition, waveguiding, Purcell-enhancement and cavity resonance tuning. The resulting photon flux is increased by more than a factor of 14 as compared to free-space. The corresponding lifetime shortening to below 460 ps puts the potential operation bandwidth beyond GHz rates. Our results mark an important step to realize quantum network nodes based on hybrid quantum photonics with SiV\\(^-\\)- center in nanodiamonds.

Hybrid quantum photonics combines classical photonics with quantum emitters in a postprocessing step. It facilitates to link ideal quantum light sources to optimized photonic platforms. Optical cavities enable to harness the Purcell-effect boosting the device efficiency. Here, we postprocess a free-standing, crossed-waveguide photonic crystal cavity based on Si\\(_3\\)N\\(_4\\) with SiV\\(^-\\) center in nanodiamonds. We develop a routine that holds the capability to optimize all degrees of freedom of the evanescent coupling term utilizing AFM nanomanipulation. After a few optimization cycles we resolve the fine-structure of individual SiV\\(^-\\) centers and achieve a Purcell enhancement of more than 4 on individual optical transitions, meaning that four out of five spontaneously emitted photons are channeled into the photonic device. Our work opens up new avenues to construct efficient quantum photonic devices.