Molecular quantum spin network controlled by a single qubit

Scalable quantum technologies will require an unprecedented combination of precision and complexity for designing stable structures of well-controllable quantum systems. It is a challenging task to find a suitable elementary building block, of which a quantum network can be comprised in a scalable way. Here we present the working principle of such a basic unit, engineered using molecular chemistry, whose control and readout are executed using a nitrogen vacancy (NV) center in diamond. The basic unit we investigate is a synthetic polyproline with electron spins localized on attached molecular sidegroups separated by a few nanometers. We demonstrate the readout and coherent manipulation of very few ($\leq 6$) of these $S=1/2$ electronic spin systems and access their direct dipolar coupling tensor. Our results show, that it is feasible to use spin-labeled peptides as a resource for a molecular-qubit based network, while at the same time providing simple optical readout of single quantum states through NV-magnetometry. This work lays the foundation for building arbitrary quantum networks using well-established chemistry methods, which has many applications ranging from mapping distances in single molecules to quantum information processing.Comment: Author name typ

Estimating Turbulence Statistics and Parameters from Ground- and Nacelle-Based Lidar Measurements:IEA Wind Expert Report

The International Energy Agency Implementing Agreement for Co-operation in the Research, Development and Deployment of Wind Energy Systems (IEA Wind) is a vehicle for member countries to exchange information on the planning and execution of national, large-scale wind system projects and to undertake co-operative research and development projects called Tasks or Annexes. As a final result of research carried out in the IEA Wind Tasks, Recommended Practices, Best Practices, or Expert Group Reports may be issued. These documents have been developed and reviewed by experts in the specialized area they address. They have been reviewed and approved by participants in the research Task, and they have been reviewed and approved by the IEA Wind Executive Committee as guidelines useful in the development and deployment of wind energy systems. Use of these documents is completely voluntary. However, these documents are often adopted in part or in total by other standards-making bodies. A Recommended Practices document includes actions and procedures recommended by the experts involved in the research project. A Best Practices document includes suggested actions and procedures based on good industry practices collected during the research project. An Experts Group Studies report includes the latest background information on the topic as well as a survey of practices, where possible. Previously issued IEA Wind Recommended Practices, Best Practices, and Expert Group Reports can be found here on the Task 11 web pages

Quantum-classical processing and benchmarking at the pulse-level

Towards the practical use of quantum computers in the NISQ era, as well as the realization of fault-tolerant quantum computers that utilize quantum error correction codes, pressing needs have emerged for the control hardware and software platforms. In particular, a clear demand has arisen for platforms that allow classical processing to be integrated with quantum processing. While recent works discuss the requirements for such quantum-classical processing integration that is formulated at the gate-level, pulse-level discussions are lacking and are critically important. Moreover, defining concrete performance benchmarks for the control system at the pulse-level is key to the necessary quantum-classical integration. In this work, we categorize the requirements for quantum-classical processing at the pulse-level, demonstrate these requirements with a variety of use cases, including recently published works, and propose well-defined performance benchmarks for quantum control systems. We utilize a comprehensive pulse-level language that allows embedding universal classical processing in the quantum program and hence allows for a general formulation of benchmarks. We expect the metrics defined in this work to form a solid basis to continue to push the boundaries of quantum computing via control systems, bridging the gap between low-level and application-level implementations with relevant metrics.Comment: 22 page

Growth and characterization of the Zintl-phase SrAl₄ on LaAlO₃

textWe present an experimental study of thin films of SrAl₄ on a LaAlO₃ substrate, with special emphasis on the Zintl-Klemm-type properties of the thin films that we grow using molecular beam epitaxy. We quantify the orientation and stoichiometry of the films and the surface morphology using reflection high energy electron diffraction (RHEED), x-ray diffraction (XRD) and atomic force microscopy (AFM). Furthermore, we present measurements of electronic properties using x-ray photoelectron spectroscopy (XPS) and ultraviolet spectroscopy (UPS). We determine the core level shifts due to the chemical environment in SrAl₄-films, which will underline the Zintl-Klemm character of the material. We measure the work function of (001)-oriented SrAl₄. Additionally we analyze the electronic transport properties of the grown thin films including the resistivity, carrier density and mobility.Pharmac

Infrared imaging of photovoltaic modules A review of the state of the art and future challenges facing gigawatt photovoltaic power stations

Thermography is a frequently used and appreciated method to detect underperforming PV modulesin PV power stations. With the review, we give insights on two aspects: 1) are the developedmeasurement strategies highly efficient (about 1 module per second) to derive timely answers fromthe images for operators of multi-MWp power stations, and 2) do PV stakeholders get answers on therelevance of thermal anomalies for further decisions. Following these questions, the influence ofmeasurement conditions, image and data collection, image evaluation as well as image assessmentare discussed. From the literature it is clear that automated image acquisition with manned andunmanned aircrafts allow to capture more than 1 module per second. This makes it possible to achievealmost identical measurement conditions for the modules; however, it is documented to what extentthe increase in speed is achieved at the expense of image resolution. Many image processing toolsbased on machine learning have been developed and show the potential for analysis of IR images anddefect classification. There are different approaches to evaluating IR anomalies in terms of impact onperformance, yield or degradation, of individual modules or modules in a string configuration. It is clearthat the problem is very complex and multi-layered. On the one hand, information on the electricalinterconnection is necessary, and on the other hand, there is a lack of sufficient and suitable data setsto adapt existing computer vision tools to PV. This is where we see the greatest need for action andfurther development to increase the expressiveness of IR images for PV stakeholder. We conclude withrecommendations to improve the outcome of IR-images and encourage the generation of suitablepublic data sets of IR-footage for the development of machine learning tools.Keywords: IR-imaging, high throughput, relevance, image acquisition, processing and assessmen

Nanostructuring mixed‐dimensional perovskites : a route toward tunable, efficient photovoltaics

2D perovskites is one of the proposed strategies to enhance the moisture resistance, since the larger organic cations can act as a natural barrier. Nevertheless, 2D perovskites hinder the charge transport in certain directions, reducing the solar cell power conversion efficiency. A nanostructured mixed‐dimensionality approach is presented to overcome the charge transport limitation, obtaining power conversion efficiencies over 9%.NRF (Natl Research Foundation, S’pore)ASTAR (Agency for Sci., Tech. and Research, S’pore)Accepted versio

Synthesis of Perfectly Oriented and Micrometer-Sized MAPbBr₃ Perovskite Crystals for Thin-Film Photovoltaic Applications

Wide band gap perovskites such as methylammonium lead bromide are interesting materials for photovoltaic applications because of their potentially high open-circuit voltage. However, the fabrication of high-quality planar films has not been investigated in detail for this material. We report a new synthesis approach for the fabrication of bromide-based perovskite planar films based on the control of the deposition environment. We achieve dense layers with large and perfectly oriented crystallites 5–10 μm in size. Our results show that large crystal sizes can be achieved only for smooth indium-doped tin oxide substrates, whereas lateral perovskite crystal growth is limited for the rougher fluorine-doped tin oxide substrates. We additionally correlate photocurrent and perovskite crystal properties in photovoltaic devices and find that this parameter is maximized for ordered systems, with internal quantum efficiencies approaching unity. Hence, our work not only gives a new pathway to tune morphology and crystal orientation but also demonstrates its importance for planar perovskite solar cells