Electron spins in diamond offer a highly interesting platform for quantum sensing and imaging technologies. The Basel Quantum Sensing Group is developing and implementing novel approaches in diamond nano-photonics to advance the performance of such sensors towards real-life applications. I will present some of these developments, with a particular focus on nanoscale magnetometry with single spins and their application to condensed matter physics.
Electron spins in diamond offer a highly interesting platform for quantum sensing and imaging technologies. The Basel Quantum Sensing Group is developing and implementing novel approaches in diamond nano-photonics to advance the performance of such sensors towards real-life applications. I will present some of these developments, with a particular focus on nanoscale magnetometry with single spins and their application to condensed matter physics.
Integrated photonic devices in diamond have tremendous potential for many quantum applications, including long-distance quantum communication, quantum information processing, and quantum sensing. These devices benefit from diamond's combination of exceptional thermal, optical, and mechanical properties. Its wide electronic bandgap makes diamond an ideal host for a variety of optical active spin qubits that are key building blocks for quantum technologies. In landmark experiments, diamond spin qubits have enabled demonstrations of remote entanglement, memory-enhanced quantum communication, and multi-qubit spin registers with fault-tolerant quantum error correction, leading to the realization of multinode quantum networks. These advances put diamond at the forefront of solid-state material platforms for quantum information processing. Recent developments in diamond nanofabrication techniques provide a promising route to further scaling of these landmark experiments towards real-life quantum technologies. In this paper, we focus on the recent progress in creating integrated diamond quantum photonic devices, with particular emphasis on spin-photon interfaces, cavity optomechanical devices, and spin-phonon transduction. Finally, we discuss prospects and remaining challenges for the use of diamond in scalable quantum technologies.
Diamond NV centers have transformed quantum sensing by enabling precise measurement of magnetic and electric fields, temperature, pressure, and strain, all within a reliable solid-state platform, at room temperature, down to the nanoscale. These capabilities position NV-based sensors as alternatives to cryogenic SQUIDs or atomic gas systems, with transformative potential across biomedical imaging, autonomous navigation, and industrial non-destructive testing (NDT). Despite promising prototypes—such as fiber-integrated endoscopes, CMOS-compatible sensors, and microfluidic chips—the development of widescale applications is hampered due to challenges in diamond micro/nanofabrication and photonic integration. Our group addresses these limitations through diamond processing techniques and hybrid material platforms. We develop methods for fabricating quantum-grade diamond nanostructures, including nanopillars optimized for neuronal electric field sensing and other photonic cavity applications. Additionally, we explore the integration of NV-rich diamond membranes within photonic systems to improve the spin photon interaction and efficient conversion of the pump beam. Collaborating with industry partner Kwantek, we also work on a compact fiber-endoscope prototype enabling NDT in constrained environments. These innovations will improve the state-of-the-art NV magnetometry to reduce system footprint and cost, critical for future industrialisation.
Many quantum technologies are dual-use technologies that can introduce new capabilities to defence and security-related applications or increase their effectiveness. In particular, diamond-based quantum sensors have great potential due to the high robustness of this material in conjunction with quantum effects accessible at room temperature. The negatively charged nitrogen vacancy centre (NV-), an atomic defect within the diamond matrix, carries an electron spin that can be actively addressed and read-out via optical and electrical means at room temperature. This electron spin is highly sensitive to external magnetic fields, temperature, and pressure and thus well-suited for quantum sensing in defence and security. Nowadays, diamond is reliably produced by means of chemical vapour deposition, allowing for tailored sensor elements, such as with oriented NV centres in layers and in microstructures that are highly interesting for vector magnetometry. Sensitive magnetometry is useful in global magnetic navigation, detecting metallic objects like submarines, human-machine interfaces and more. Apart from that, radiofrequency signals are detected in real-time with GHz spectral coverage in radar analysis. Recently, the use of these diamond-based quantum sensing technologies for side-channel attacks has come into focus, for example, to gather information on implementation of algorithms for cryptosystems. These technologies are introduced along with the fabrication of the underlying diamond sensor element.
Quantum sensing aims to detect signals with unparalleled sensitivity, potentially surpassing classical limitations. Solid-state spin defects, particularly nitrogen-vacancy centers in diamond, have emerged as promising platforms due to their long coherence time, optical addressability, high field sensitivity, and spatial and spectral resolution, making them ideal for sensing and imaging applications. Their compact size and robust performance under room temperature and ambient conditions further enhance their suitability for real-world applications. We provide an overview of quantum sensing principles and explore efforts to improve sensor functionality, including advanced sensing protocols, spatial imaging techniques, and integration with optical systems to enhance detection efficiency. We also highlight recent progress in the applications of these sensors across various use cases, including biomedical diagnostics, semiconductor device inspection, and industrial and military applications.
Abstract : This report summarizes our recent progress on the development of photonic nanostructures for sensing and information processing. We have developed a nitrogen vacancy (NV) spin qubit-cavity system in the strong Purcell regime in which the spin qubit predominantly interacts with the cavity mode. This system is realized in a single-crystal diamond photonic crystal nanocavity with quality factors (Q) up to 104. Furthermore, we measure electron spin coherence times of cavity-coupled NVs of 200 us. We have also developed techniques for NV-based super-resolution imaging and precision sensing, using high-speed parallel readout on a microscope camera; and we have developed techniques for precision clocks based on collective oscillation of ensembles of NVs. We also report on graphene electro-optic devices and sensors.
Development of quantum information processing requires realization of solid state structures able to manipulate light or matter quantum bits. One of the promising candidates for been active elements of such solid-state platform are color centers in diamond. The most famous nitrogen-vacancy color center has number of attractive features and found a lot of applications in sensing and imaging. Still, it has number of considerable disadvantages, among which it sensitivity to the surface damages and thus its incompatibility with nanostructures. On another side implementation of nano- and micro- structures enabled considerable progress in manipulation of light quanta. In particular photonic crystal cavities allowed to realize strong coupling of cavity and spin system. This led to demonstration of efficient light collection and realization of simple quantum gates with artificial or real atoms. Novel color centers such as silicon-vacancy or germanium-vacancy color center due to inversion symmetry of the electron structure are not sensitive to the surface damages and presence of surface nearby. Thus, those are perfect candidates for been combined with photonic crystal structures. Novel technologies enabled growing of the nanodiamonds of ultra-small size having well-defined color center inside. Along with techniques to position those precisely on the nano- and micro structures these achievements opened opportunity to integrate high-fines photonic-crystal cavities with the germanium-vacancy containing nanocrystals thus forming fully solid-state platform for quantum manipulation of light. In my talk I will describe our progress towards realization of this ambitious goal.