Designing solid-state quantum sensors for brain imaging

量子物理学是许多重要的生物医学成像技术的基础，如磁共振成像（MRI）或正电子发射断层扫描（PET）。脑磁图（MEG）是一种基于测量颅骨外微小磁场的有前途的新型非侵入性成像技术，已在临床上使用，例如在计划脑部手术时用于区分健康组织和不健康组织。目前，MEG通常使用超导量子干涉器件（SQUID）。这些传感器需要低温冷却，导致需要相当庞大的扫描仪，患者必须保持完全静止，这限制了许多潜在的应用。最近，正在开发基于原子蒸气的新型传感器。这些所谓的光泵磁力计（OPM）具有无需低温冷却即可工作的优点，并开始商业化。这种OPM的一个限制是它们相对低的空间分辨率，其在几毫米的尺度上。基于金刚石中氮空位（NV）中心的固态传感器也不需要低温冷却，同时有望获得更高的（微米级）空间分辨率。它们开始应用于研究环境中的生物医学成像，但与OPM相比处于早期发展阶段。我们的团队由NV中心的量子技术（Simon，Barclay）和金刚石纳米纤维（Barclay）以及神经科学（Simon）的专家组成。利用这一专业知识，我们将设计基于NV中心的微腔增强吸收量子传感器的芯片阵列。我们的设计将通过与SQUID和基于OPM的方法进行广泛的比较，对我们基于NV的系统进行详细的理论建模，以及进行初步实验。我们的目标是使该技术能够成为应用于AICE等健康相关资助项目的基础，并产生商业利益（从目前的TRL 2到TRL 4）。

Quantum physics is the foundation for many important biomedical imaging techniques such as magnetic resonance imaging (MRI) or positron emission tomography (PET). Magnetoencephalography (MEG) is a promising new non-invasive imaging technique based on measuring the tiny magnetic field outside the skull, which is already being used clinically, e.g. for distinguishing healthy from unhealthy tissue when planning brain surgeries. Currently MEG typically uses superconducting quantum interference devices (SQUIDs). These sensors require cryogenic cooling, resulting in the need for quite bulky scanners, where patients have to hold completely still, which is limiting for many potential applications. More recently new types of sensors based on atomic vapors are being developed. These so-called optically pumped magnetometers (OPMs) have the advantage that they can operate without cryogenic cooling and are beginning to be commercialized. One limitation of such OPMs is their relatively low spatial resolution, which is on the scale of several millimeters. Solid-state sensors based on nitrogen-vacancy (NV) centers in diamond also do not require cryogenic cooling, while promising much higher (micron-scale) spatial resolution. They are starting to be applied to biomedical imaging in research settings, but are in an earlier stage of development compared to OPMs. Our team consists of experts on NV center based quantum technology (Simon, Barclay) and diamond nanofabrication (Barclay), as well as neuroscience (Simon). Leveraging this expertise, we will design chip-based arrays of micro-cavity enhanced absorptive quantum sensors based on NV centers. Our design will be informed by a broad comparison with SQUID and OPM based approaches, on detailed theoretical modeling of our NV-based systems, as well as on initial experiments. Our goal is to bring the technology to the point where it can be the basis for applications to health-related funding programs such as AICE and generate commercial interest (from currently TRL 2 to TRL 4).