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Quality assurance for online adaptive radiotherapy: a secondary dose verification model with geometry-encoded U-Net. 在线自适应放射治疗的质量保证：采用几何编码 U-Net 的二次剂量验证模型。

IF 6.3 2区材料科学 Q2 MATERIALS SCIENCE, MULTIDISCIPLINARY

ACS Applied Nano Materials

Pub Date : 2024-12-01 Epub Date: 2024-10-11 DOI: 10.1088/2632-2153/ad829e

Shunyu Yan, Austen Maniscalco, Biling Wang, Dan Nguyen, Steve Jiang, Chenyang Shen

In online adaptive radiotherapy (ART), quick computation-based secondary dose verification is crucial for ensuring the quality of ART plans while the patient is positioned on the treatment couch. However, traditional dose verification algorithms are generally time-consuming, reducing the efficiency of ART workflow. This study aims to develop an ultra-fast deep-learning (DL) based secondary dose verification algorithm to accurately estimate dose distributions using computed tomography (CT) and fluence maps (FMs). We integrated FMs into the CT image domain by explicitly resolving the geometry of treatment delivery. For each gantry angle, an FM was constructed based on the optimized multi-leaf collimator apertures and corresponding monitoring units. To effectively encode treatment beam configuration, the constructed FMs were back-projected to $30$ cm away from the isocenter with respect to the exact geometry of the treatment machines. Then, a 3D U-Net was utilized to take the integrated CT and FM volume as input to estimate dose. Training and validation were performed on $381$ prostate cancer cases, with an additional $40$ testing cases for independent evaluation of model performance. The proposed model can estimate dose in ∼ $15$ ms for each patient. The average γ passing rate ( $3 % / 2 mm$ , $10 %$ threshold) for the estimated dose was 99.9% ± 0.15% on testing patients. The mean dose differences for the planning target volume and organs at risk were $0.07 % \pm 0.34 %$ and $0.48 % \pm 0.72 %$ , respectively. We have developed a geometry-resolved DL framework for accurate dose estimation and demonstrated its potential in real-time online ART doses verification.

在在线自适应放射治疗（ART）中，当病人被安置在治疗床上时，基于快速计算的二次剂量验证对于确保 ART 计划的质量至关重要。然而，传统的剂量验证算法一般都很耗时，降低了 ART 工作流程的效率。本研究旨在开发一种基于深度学习（DL）的超快速二次剂量验证算法，利用计算机断层成像（CT）和通量图（FMs）准确估计剂量分布。我们通过明确解析治疗投放的几何形状，将通量图整合到 CT 图像域中。对于每个龙门架角度，我们都根据优化的多叶准直器孔径和相应的监测单元构建了一个 FM。为有效编码治疗光束配置，根据治疗机的精确几何形状，将构建的调频反向投影到距离等中心 30 厘米的位置。然后，利用三维 U-Net 将集成 CT 和调频体积作为输入来估算剂量。对 381 个前列腺癌病例进行了训练和验证，另外还对 40 个测试病例进行了独立的模型性能评估。建议的模型能在 15 毫秒内估算出每位患者的剂量。在测试患者中，估计剂量的平均γ通过率（3 % / 2 mm，10 %阈值）为 99.9% ± 0.15%。规划靶体积和危险器官的平均剂量差异分别为 0.07 % ± 0.34 % 和 0.48 % ± 0.72 %。我们开发出了一种用于精确剂量估算的几何分辨 DL 框架，并证明了其在实时在线 ART 剂量验证中的潜力。

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引用次数: 0

Highly Reversible Tuning of Light-Matter Interactions in Van der Waals Materials Coupled with Hydrogel-Assisted Optical Cavity

IF 11 1区物理与天体物理 Q1 OPTICS

Laser & Photonics Reviews

Pub Date : 2024-11-19 DOI: 10.1002/lpor.202401263

Lanxin Xu, Jiaqi Wang, Zishun Li, Peng Xie, Qi Ding, Minghao An, Yingjie Zhao, Yiheng Tang, Lan Li, Chengchen Guo, Wei Wang, Xiaorui Zheng

Controlling light-matter interactions via cavity systems manifested by Rabi splitting is paramount important for nanophotonics. However, achieving conveniently accessible and active tuning of light-matter interactions remains a formidable challenge. Traditional approaches often necessitate either sophisticated design or meticulous nanofabrication to address this issue. Here, a handy strategy is experimentally demonstrated to build an adjustable coupling system featuring reversibly modulated responses based on dielectric-hydrogel-metal resonators. By controlling the top tungsten disulfide layer thickness, the flexible manipulation of weak-intermediate-strong transitions in exciton-cavity interactions is revealed on a large-scale hydrogel membrane without nanopositioning or lithography. Crucially, by leveraging the inflation sensitivity of the hydrogel, the coupling strength can be reversibly tailored with excellent reproducibility by modulating the resonator's dry/immersed states. The combined merits of captivating design and daily stimulus render the novel hydrogel-based nanocavities as a groundbreaking step toward the development of active and practical integrated optical devices, such as polariton lasing, switches, and sensors.

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引用次数: 0

Coupling Single Molecules to DNA-Based Optical Antennas with Position and Orientation Control

IF 7 1区物理与天体物理 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

ACS Photonics

Pub Date : 2024-11-19 DOI: 10.1021/acsphotonics.4c01506

Aleksandra K. Adamczyk, Fangjia Zhu, Daniel Schäfer, Yuya Kanehira, Sergio Kogikoski, Jr., Ilko Bald, Sebastian Schlücker, Karol Kołątaj, Fernando D. Stefani, Guillermo P. Acuna

Optical antennas have been extensively employed to manipulate the photophysical properties of single-photon emitters. Coupling between an emitter and a given resonant mode of an optical antenna depends mainly on three parameters: spectral overlap, relative distance, and relative orientation between the emitter’s transition dipole moment and the antenna. While the first two have already been extensively demonstrated, achieving full coupling control remains unexplored due to the challenges in manipulating at the same time both the position and orientation of single molecules. Here, we use the DNA origami technique to assemble a dimer optical antenna and position a single fluorescent molecule at the antenna gap with controlled orientation, predominately parallel or perpendicular to the antenna’s main axis. We study the coupling for both conditions through fluorescence measurements correlated with scanning electron microscopy images, revealing a 5-fold higher average fluorescence intensity when the emitter is aligned with the antenna’s main axis and a maximum fluorescence enhancement of ∼1400-fold. A comparison to realistic numerical simulations suggests that the observed distribution of fluorescence enhancement arises from small variations in the emitter orientation and gap size. This work establishes DNA origami as a versatile platform to fully control the coupling between emitters and optical antennas, trailblazing the way for self-assembled nanophotonic devices with optimized and more homogeneous performance.

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引用次数: 0

Ultracompact Polarization-Insensitive 1 × N Silicon-Based Optical Wavelength-Selective Switch by Leveraging I/O Waveguide Spacing Difference

IF 7 1区物理与天体物理 Q1 MATERIALS SCIENCE, MULTIDISCIPLINARY

ACS Photonics

Pub Date : 2024-11-19 DOI: 10.1021/acsphotonics.4c01606

Zhuping Fan, Xiongshuo Yan, Zhenyu Li, Xiao Ma, Tingting Lang, Dihai Dai, Xuyang Wang, Jun Zou

Wavelength-selective switches (WSS) have large potential applications in future high-capacity, low-latency, flexible, and energy-efficient data center optical networks. Here, a novel ultracompact 1 × N polarization-insensitive WSS is proposed on the silicon-on-insulator (SOI) platform. The WSS comprises one input port with a polarizing beam splitter and rotator (PBSR), two identical (M × N + 1) × (M + N) arrayed waveguide gratings (AWGs) cascaded with M 1 × N thermo-optic (TO) switches, and N output ports with polarization combiners. The AWG works as both a demultiplexer and multiplexer to eliminate the center wavelength mismatch induced by fabrication errors and to achieve an ultracompact footprint. The TO switches placed on loopback arms allow for the routing of each wavelength to any one of the N output ports. A new design of leveraging the I/O waveguide spacing difference between the loopback inputs and demultiplexing outputs of AWG is employed to eliminate waveguide crossings in a conventional WSS layout design. In experiment, a 12-channel 400 GHz spacing 1 × 2 WSS with a footprint of 1.67 × 1.7 mm² is demonstrated. The minimal on-chip loss of 6.8 dB, best extinction ratio of 25 dB, and switching speed of 42 μs are achieved. The measured polarization-dependent loss is <0.5 dB and polarization-dependent wavelength shift is <0.08 nm.

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引用次数: 0

Numerical model of N-level cascade systems for atomic Radio Frequency sensing applications 用于原子射频传感应用的 N 级级联系统数值模型

IF 5.8 2区物理与天体物理 Q1 OPTICS

EPJ Quantum Technology

Pub Date : 2024-11-18 DOI: 10.1140/epjqt/s40507-024-00291-5

Liam W. Bussey, Yogeshwar B. Kale, Samuel Winter, Fraser A. Burton, Yu-Hung Lien, Kai Bongs, Costas Constantinou

A ready-to-use numerical model has been developed for the atomic ladder (cascade) systems which are widely exploited in Rydberg Radio Frequency (RF) sensors. The model has been explicitly designed for user convenience and to be extensible to arbitrary N-level non-thermal systems. The versatility and adaptability of the model is validated up to 4-level atomic systems by direct comparison with experimental results from the prior art. The numerical model provides a good approximation to the experimental results and provides experimentalists with a convenient ready-to-use model to optimise the operation of an N-level Rydberg RF sensor. Current sensors exploit the 4-level atomic systems based on alkali metal atoms which require visible frequency lasers and these can be expensive and also suffer from high attenuation within optical fiber. The ability to quickly and simply explore more complex N-level systems offers the potential to use cheaper and lower-loss near-infrared lasers.

针对雷德贝格射频（RF）传感器中广泛使用的原子阶梯（级联）系统，我们开发了一种即用型数值模型。该模型设计明确，方便用户使用，并可扩展到任意 N 级非热系统。通过与现有技术的实验结果进行直接比较，该模型的多功能性和适应性得到了验证，最高可达 4 级原子系统。该数值模型提供了与实验结果的良好近似，并为实验人员提供了方便的即用模型，以优化 N 级雷德堡射频传感器的运行。目前的传感器利用基于碱金属原子的 4 级原子系统，这种系统需要可见光频率的激光器，而这些激光器价格昂贵，在光纤中还会出现高衰减。能够快速、简单地探索更复杂的 N 级系统，为使用更便宜、损耗更低的近红外激光器提供了可能。

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引用次数: 0

Nanoring Tamm cavity in the telecommunications O band

IF 4 2区物理与天体物理 Q2 PHYSICS, APPLIED

Applied Physics Letters

Pub Date : 2024-11-18 DOI: 10.1063/5.0213200

Huili Hou, David Dlaka, Jon Pugh, Ruth Oulton, Edmund Harbord

Quantum and classical telecommunications require efficient sources of light. Semiconductor sources, owing to the high refractive index of the medium, often exploit photonic cavities to enhance the external emission of photons into a well-defined optical mode. Optical Tamm States (OTSs) in which light is confined between a distributed Bragg reflector and a thin metal layer have attracted interest as confined Tamm structures are readily manufactureable broadband cavities. Their efficiency is limited however by the absorption inherent in the metal layer. We propose a nanoring Tamm structure in which a nanoscale patterned annular metasurface is exploited to reduce this absorption and thereby enhance emission efficiency. To this end, we present designs for a nanoring Tamm structure optimized for the telecommunications O band and demonstrate a near doubling of output efficiency (35%) over an analogous solid disk confined Tamm structure (18%). Simulations of designs optimized for different wavelengths are suggestive of annular coupling between the Tamm state and surface plasmons. These designs are applicable to the design of single photon sources, nano-LEDs, and nanolasers for communications.

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引用次数: 0

Sodium carbonates on Ryugu as evidence of highly saline water in the outer Solar System 龙宫上的碳酸钠是外太阳系高盐度水的证据

IF 14.1 1区物理与天体物理 Q1 ASTRONOMY & ASTROPHYSICS

Nature Astronomy

Pub Date : 2024-11-18 DOI: 10.1038/s41550-024-02418-1

Toru Matsumoto, Takaaki Noguchi, Akira Miyake, Yohei Igami, Megumi Matsumoto, Toru Yada, Masayuki Uesugi, Masahiro Yasutake, Kentaro Uesugi, Akihisa Takeuchi, Hayato Yuzawa, Takuji Ohigashi, Tohru Araki

Water activity recorded in asteroids offers a perspective on their habitability. Aqueous alteration, namely the interaction of liquid water with minerals, occurred in the parent body of the C-type asteroid Ryugu. However, Ryugu is not a wet body, and the processes that led to the loss of liquid water along with its chemical environment remain unclear. We report the presence of sodium carbonates, chlorides and sulfates in Ryugu samples, which indicate that alkaline, salt-rich water once flowed through its parent body. Highly concentrated brine probably formed through evaporation or freezing of the liquid water in the final stages of aqueous alteration. Similar processes may have occurred in carbonaceous asteroids in the Solar System, although terrestrial weathering of meteorites might obscure evidence of salt precipitation. Sodium salts could be crucial for comparing the evolved water in carbonaceous bodies and alkaline subsurface oceans in the dwarf planet Ceres and the moons of Jupiter and Saturn.

小行星中记录的水活动为研究其宜居性提供了一个视角。C型小行星 "龙宫 "的母体发生了水蚀作用，即液态水与矿物的相互作用。然而，"龙宫 "并不是一个湿润的天体，导致液态水消失的过程及其化学环境仍不清楚。我们报告了龙宫样本中碳酸钠、氯化物和硫酸盐的存在，这表明富含盐分的碱性水曾经流经其母体。高浓度的盐水可能是在水蚀作用的最后阶段通过液态水的蒸发或冻结形成的。太阳系中的碳质小行星也可能发生过类似的过程，尽管陨石的陆地风化可能会掩盖盐沉淀的证据。钠盐可能是比较碳质天体中的进化水和矮行星谷神星及木星和土星卫星中的碱性地表下海洋的关键。

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引用次数: 0

Reducing measurement costs by recycling the Hessian in adaptive variational quantum algorithms 在自适应变分量子算法中通过回收赫塞斯降低测量成本

IF 6.7 2区物理与天体物理 Q1 PHYSICS, MULTIDISCIPLINARY

Quantum Science and Technology

Pub Date : 2024-11-18 DOI: 10.1088/2058-9565/ad904e

Mafalda Ramôa, Luis Paulo Santos, Nicholas J Mayhall, Edwin Barnes and Sophia E Economou

Adaptive protocols enable the construction of more efficient state preparation circuits in variational quantum algorithms (VQAs) by utilizing data obtained from the quantum processor during the execution of the algorithm. This idea originated with Adaptive Derivative-Assembled Problem-Tailored variational quantum eigensolver (ADAPT-VQE), an algorithm that iteratively grows the state preparation circuit operator by operator, with each new operator accompanied by a new variational parameter, and where all parameters acquired thus far are optimized in each iteration. In ADAPT-VQE and other adaptive VQAs that followed it, it has been shown that initializing parameters to their optimal values from the previous iteration speeds up convergence and avoids shallow local traps in the parameter landscape. However, no other data from the optimization performed at one iteration is carried over to the next. In this work, we propose an improved quasi-Newton optimization protocol specifically tailored to adaptive VQAs. The distinctive feature in our proposal is that approximate second derivatives of the cost function are recycled across iterations in addition to optimal parameter values. We implement a quasi-Newton optimizer where an approximation to the inverse Hessian matrix is continuously built and grown across the iterations of an adaptive VQA. The resulting algorithm has the flavor of a continuous optimization where the dimension of the search space is augmented when the gradient norm falls below a given threshold. We show that this inter-optimization exchange of second-order information leads the approximate Hessian in the state of the optimizer to be consistently closer to the exact Hessian. As a result, our method achieves a superlinear convergence rate even in situations where the typical implementation of a quasi-Newton optimizer converges only linearly. Our protocol decreases the measurement costs in implementing adaptive VQAs on quantum hardware as well as the runtime of their classical simulation.

自适应协议通过利用在算法执行过程中从量子处理器获取的数据，能够在变量子算法（VQAs）中构建更高效的状态准备电路。这种算法逐个算子迭代地增长状态准备电路，每个新算子都伴随着一个新的变分参数，而且迄今为止获得的所有参数都在每次迭代中得到优化。ADAPT-VQE 及其后的其他自适应 VQA 均表明，将参数初始化为上一次迭代的最优值可加快收敛速度，并避免参数景观中的浅局部陷阱。但是，在一次迭代中进行的优化所产生的其他数据不会被带到下一次迭代中。在这项工作中，我们提出了一种专门针对自适应 VQA 的改进型准牛顿优化协议。我们建议的显著特点是，除了最优参数值外，成本函数的近似二次导数也会在迭代中循环使用。我们实现了一种准牛顿优化器，在这种优化器中，逆黑森矩阵的近似值会在自适应 VQA 的迭代过程中不断建立和增长。由此产生的算法具有连续优化的特点，当梯度法低于给定阈值时，搜索空间的维度会增加。我们的研究表明，这种优化间的二阶信息交换会使优化器状态下的近似赫塞斯不断接近精确赫塞斯。因此，即使在准牛顿优化器的典型实现仅为线性收敛的情况下，我们的方法也能达到超线性收敛率。我们的协议降低了在量子硬件上实现自适应 VQA 的测量成本以及其经典模拟的运行时间。

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引用次数: 0

Artificial mechano-nociceptive system based on transparent ITO/AlN/ITO memristor nociceptor neuron 基于透明 ITO/AlN/ITO忆阻器痛觉神经元的人工机械痛觉系统

IF 4 2区物理与天体物理 Q2 PHYSICS, APPLIED

Applied Physics Letters

Pub Date : 2024-11-18 DOI: 10.1063/5.0235758

Caiyang Ye, Yimeng Xu, Ziyi Dai, Zede Zhu, Chao Li, Kai Qian

Artificial nociceptors demonstrate significant potential in emerging fields such as intelligent prosthetics, humanoid robotics, and electronic skin, capable of transducing external noxious stimuli to the central nervous system. Unlike common sensory neurons, nociceptors exhibit unique characteristics, including “no adaptation,” “relaxation,” “threshold firing,” and “sensitization of allodynia/hyperalgesia.” This study presents a forming-free volatile transparent ITO/AlN/ITO memristor that emulates biological nociceptor behaviors. Leveraging this artificial nociceptor, an artificial mechano-nociceptive system is developed by integrating the ITO/AlN/ITO memristor into a piezoelectric force sensor system for pain sensing and noxious stimuli warning. This research contributes to the advancement of human cognitive capability emulation and artificial intelligence systems, particularly in the domain of pain perception and response.

人造痛觉感受器在智能假肢、仿人机器人和电子皮肤等新兴领域具有巨大潜力，能够将外部有害刺激传导至中枢神经系统。与普通感觉神经元不同，痛觉感受器表现出独特的特征，包括 "无适应"、"松弛"、"阈值点燃 "和 "异感/过痛敏感化"。本研究提出了一种无成型挥发性透明 ITO/AlN/ITO 记忆晶闸管，可模拟生物痛觉感受器的行为。利用这种人工痛觉感受器，将 ITO/AlN/ITO 记忆晶粒集成到压电力传感器系统中，开发出了一种人工机械痛觉系统，用于痛觉感应和有害刺激预警。这项研究有助于推动人类认知能力仿真和人工智能系统的发展，特别是在疼痛感知和反应领域。

引用次数: 0

Pulsed N2 plasma surface treatment for AlGaN/GaN HEMTs prior to PECVD SiNx passivation to reduce plasma damage 在 PECVD SiNx 钝化之前对 AlGaN/GaN HEMT 进行脉冲 N2 等离子表面处理以减少等离子损伤

IF 4 2区物理与天体物理 Q2 PHYSICS, APPLIED

Applied Physics Letters

Pub Date : 2024-11-18 DOI: 10.1063/5.0235740

Kaiyu Wang, Ke Wei, Ruizhe Zhang, Sheng Zhang, Jiaqi Guo, Xiaoqiang He, Jianchao Wang, Sen Huang, Yingkui Zheng, Xiaojuan Chen, Xinhua Wang, Xinyu Liu

In this work, a pulse-mode N2 plasma surface treatment process was proposed as a means of reducing plasma damage and improving the GaN/GaOx ratio on the surface before SiNx deposition, which further contributes to an enhanced density of 2DEG and a reduced sheet resistance. With the pulsed N2 plasma surface treatment combined with subsequent SiNx passivation, the fabricated GaN HEMTs exhibit negligible current collapse and suppressed leakage current. The improved behavior is attributed to the fact that the pulsed N2 plasma is capable of nitriding the surface and removing carbon contaminants as identified through x-ray photoelectron spectroscopy and energy dispersive x-ray spectroscopy. Compared to the traditional continuous-wave-mode N2 plasma, the pulsed N2 plasma pre-treatment effectively prevents continuous collisions of the plasma during acceleration, thereby significantly reducing plasma damage. This work offers valuable insights for surface treatment processes in micro- and nanofabrication.

在这项工作中，提出了一种脉冲模式 N2 等离子体表面处理工艺，作为在 SiNx 沉积之前减少等离子体损伤和改善 GaN/GaOx 表面比率的一种手段，这进一步有助于提高 2DEG 密度和降低薄层电阻。脉冲 N2 等离子体表面处理与随后的 SiNx 钝化相结合，制造出的 GaN HEMT 具有可忽略的电流塌陷和受抑制的漏电流。通过 X 射线光电子能谱分析和能量色散 X 射线能谱分析发现，脉冲 N2 等离子体能够使表面氮化并去除碳污染物，从而改善了性能。与传统的连续波模式 N2 等离子体相比，脉冲 N2 等离子体预处理可有效防止等离子体在加速过程中发生连续碰撞，从而显著减少等离子体损伤。这项工作为微米和纳米制造中的表面处理工艺提供了宝贵的启示。

引用次数: 0

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