A quantum-enhanced magnetometer using a single high-spin nucleus in silicon

Quantum enhanced metrology has the potential to go beyond the standard quantum limit and eventually to the ultimate Heisenberg bound.In particular,quantum probes prepared in nonclassical coherent states have recently been recognized as a useful resource for metrology.Hence,there has been considerable interest in constructing magnetic quantum sensors that combine high resolution and high sensitivity.Here,we explore a nanoscale magnetometer with quantum-enhanced sensitivity,based on 123Sb(I=7/2)nuclear spin doped in silicon,that takes advantage of techniques of spin-squeezing and coherent control.With the optimal squeezed initial state,the magnetic field sensitivity may be expected to approach 6 aT·Hz^(−1/2)·cm^(−3/2) and 603 nT·Hz^(−1/2) at the single-spin level.This magnetic sensor may provide a novel sensitive and high-resolution route to microscopic mapping of magnetic fields as well as other applications.

基于便携式坐标测量机的大齿轮测量方法

针对目前便携式坐标测量机测量大齿轮的采样策略和评定算法存在的不足,设计了两种特殊的辅助标尺-渐开线标尺及螺旋线标尺。利用设计的两种标尺在大齿轮齿面上对齿廓及螺旋线的测量点进行标注,开展了齿轮的在位重复性测量的实验研究。利用关节臂坐标测量机及激光跟踪仪测量系统在德国计量研究院研制的1m外径齿轮样板上开展了测量实验,采用INVOLUTE Pro对采样数据点进行评定,给出了测量结果及测量不确定度。测量实验表明,基于新的齿轮测量方法,关节臂坐标测量机比激光跟踪仪测量系统测量结果更为精确,测试结果与标定值最大相差8.16μm。实验结果验证了提出方法的有效性,为便携式坐标测量机在大齿轮测量领域的应用提供了依据。

计量软件溯源中的TraCIM软件认证系统

工业计量领域、校准实验室和计量研究机构均需要一致的计算溯源框架以对计量软件进行溯源。计量软件溯源主要是对其算法进行溯源,并与其特定的计算目标相关联。德国国家计量院(PTB)推出了国际计量软件认证系统(TraCIM)实施计量软件溯源,国际软件认证包括高斯(Gauss)软件认证、切比雪夫(Chebyshev)软件认证和比对(Comparison)软件认证。TraCIM计量软件认证通过在专用网络平台上实施"认证用户—服务器"间的应用来实现。认证流程主要包括索要标准输入数据、提交结果和获得认证报告。计量领域企业三丰(Mitutoyo)、蔡司(Zeiss)均实施并通过认证。

X射线辐射测量(英文)

在过去的几年里,人们使用同步辐射技术在X射线波段实现了基于辐射源和基于探测器的辐射测量,电子储存环被用作主辐射源标准,而低温辐射计(ESR)被用作主探测器标准。因为低温辐射计需要强的单色辐射,所以,这种方式也必须使用同步辐射。文中对能量色散探测器和硅光电二极管的探测效率和响应度做了校准,其相对不确定度约1 %,所得结果与模型计算值做了比较。

不同流量条件下水表性能的研究与表征

利用光学、非侵入式激光技术的优点,研究了在机械水表前端和内部的不同流量条件对水表计量性能的影响。重点用激光多普勒测速计(LDA)测量的三维速度分布与水表在理想、扰动流型及不同流量下的误差曲线进行了比较。文章给出了具体的技术方案以及优化后的LDA数据处理和展示过程。除了通过各种2D和3D图定性描述流态外,还定义了无量纲参数以实现定量描述,目的在于建立一个可以预测水表示值变化的模型。

Model based reference metrology for dimensional characterization of micro- and nanostructures

The requirements on the precision of dimensional metrology are especially stringent in the area of semiconductor manufacturing. This holds in particular for the measurement and control of the linewidths of the smallest structures on masks and silicon wafers and their corresponding reference metrology. In this paper we will describe the physical models and the reference instrumentation which were developed for photomask linewidth metrology at the PTB. It will be shown, how the results of the different methods can be used for comparative analyses. Application of these methods will be demonstrated exemplarily on the basis of newly developed photomask linewidth standards.

Uncertainty Calculation of Roundness Assessment by Automatic Differentiation in Coordinate Metrology

Reomtly, Coordinate bieasuring Machines （CMMs） are widely used to measure roundness errors. Roundness is calculated from a large number of points collected from the profiles of the parts. According to the Guide to the Expression of Uncertainty in Measta- meat （GUM）, all measurement results must have a stated uncertainty associated the titan. However, no CMMs give the uncertainty value of the roundness, because no suitable measrement uncertainty calculation procedure exists. In the case of roundness raeasurement in coordinate metrology, this paper suggests the algorithms for the calculation of the measurement uncertainty of the roudness deviation based on the two mainly used association criteria, LSC and MZC. The calculation of the sensitivity coefficients for the uncertainty calculatiion can be done by autnatic differentiation, in order to avoid introducing additional emars by the traditional difference quotient approxima- tions. The proposed methods are exact and need input data only as the nrasured coordinates of the data points and their associated un- certainties.

Cryocooler Operation of a Pulse-Driven AC Josephson Voltage Standard at PTB

The PTB Josephson Arbitrary Waveform Synthesizer (JAWS) enables the generation of arbitrary waveforms up to voltages of 70 mVRMS (199 mVPP) using two Josephson arrays in series containing 4000 Josephson junctions each. The SNS-like double-stacked junctions are based on NbxSi1-x as barrier material. While the JAWS system is typically operated using a Dewar with liquid helium, the operation in a closed-cycle pulse-tube cryocooler at temperatures around 4.2 K range was here investigated and successfully demonstrated. For this purpose a special designed cryoprobe was used to provide high quality pulses to the Josephson arrays.

Towards Quantitative Characterisation of the Small Force Transducer Used in Nanoindentation Instruments

Quantitative characterization of the mechanical properties of materials in micro-/nano-scale using depth-sensing indentation technique demands high performance of nanoindentation instruments in use. In this paper, the efforts to calibrate the capacitive force transducer of a commercial nanoindentation instrument are presented, where the quasi-static characteristic of the force transducer has been calibrated by a precise compensation balance with a resolution of ~1 nN. To investigate the dynamic response of the transducer, an electrostatic MEMS (Micro-Electro-Mechanical System) based on nano-force transfer standard with nano-Newton (10-9 Newton) resolution and a bandwidth up to 6 kHz have been employed. Preliminary experimental results indicate that 1) the force transducer under calibration has a probing force uncertainty less than 300 nN (1σ) in the calibration range of 1 mN;2) the transient duration at contact points amounts to 10 seconds;3) the overshoot of engagement is pre-load dependent.

Microwave Design and Performance of PTB 10 V Circuits for the Programmable Josephson Voltage Standard

At Physikalisch-Technische Bundesanstalt (PTB), superconducting 10 V circuits for the programmable Josephson voltage standard (PJVS) are routinely manufactured on the basis of NbxSi1-x barrier junctions. This paper describes in detail the basic design principles for an operating frequency of 70 GHz. It starts with single junctions, discusses their insertion into microstriplines and closes with the whole microwave circuit containing 69,632 NbxSi1-x barrier junctions arranged over 128 microstriplines connected in parallel. The microwave attenuation of this junction type is a key parameter for the 10 V design and we report its experimental determination. Special attention has been devoted to subarrays with just a few Josephson junctions in one of the outermost striplines. The arrangement of these subarrays determines the optimum performance of the complete 10 V series array. The high performance of programmable 10 V circuits fabricated at PTB is characterized by measured operating margins in all subarrays of more than 1 mA centered at the same dc bias current. The observed modulation of the current margins, when changing the frequency around 70 GHz, is explained by microwave reflections caused by the rf waveguide inside the cryoprobe. We determine the current margins in dependence of the output power of a microwave synthesizer and show that 60 mW is sufficient to achieve current margins larger than 1 mA.

Stabilization of Silica Gel against Hydrolysis by Doping with F^(-) or Zr(Ⅳ)

Silica gel (SG) was synthesized via acidification of sodium silicate solution then doped with Fˉ or Zr(IV) in molar ratios of F/Si 3/100, and Zr/Si 0.75/100 and 3.75/100 and sintered at 500°C, 800°C and 1000°C. The samples were investigated by X-ray diffractometry, infrared absorption and Raman spectra, surface area measurement, and inductively coupled plasma-optical emission spectrometry-monitored silica hydrolysis. All samples are mesoporous with BET surface areas 181.5 - 523.9 m2·gˉ1. The surface area of the silica samples decreases as the sintering temperature increases. The hydrolysis process of silica decreases as the sintering temperature increases and as the surface area decreases. The pH and the type of buffer solution affect the hydrolysis of silica samples due to a SN2 reaction mechanism favored in basic media using ammonia buffer. Zr(IV) increases the stability of silica samples against the hydrolysis as confirmed by the structural investigation, surface area and silica hydrolysis. Fˉ observably decreases the silica hydrolysis process when presenting on the surface of SG.

High-rate intercity quantum key distribution with a semiconductor single-photon source

Quantum key distribution(QKD)enables the transmission of information that is secure against general attacks by eavesdroppers.The use of on-demand quantum light sources in QKD protocols is expected to help improve security and maximum tolerable loss.Semiconductor quantum dots(QDs)are a promising building block for quantum communication applications because of the deterministic emission of single photons with high brightness and low multiphoton contribution.Here we report on the first intercity QKD experiment using a bright deterministic single photon source.A BB84 protocol based on polarisation encoding is realised using the high-rate single photons in the telecommunication C-band emitted from a semiconductor QD embedded in a circular Bragg grating structure.Utilising the 79 km long link with 25.49 dB loss(equivalent to 130 km for the direct-connected optical fibre)between the German cities of Hannover and Braunschweig,a record-high secret key bits per pulse of 4.8 ×10^(-5) with an average quantum bit error ratio of~0.65%are demonstrated.An asymptotic maximum tolerable loss of 28.11 dB is found,corresponding to a length of 144 km of standard telecommunication fibre.Deterministic semiconductor sources therefore challenge state-of-the-art QKD protocols and have the potential to excel in measurement device independent protocols and quantum repeater applications.

A New Kind of Atomic Force Microscopy Scan Control Enabled by Artificial Intelligence:Concept for Achieving Tip and Sample Safety Through Asymmetric Control

This paper introduces a paradigm shift in atomic force microscope(AFM)scan control,leveraging an artificial intelligence(AI)-based controller.In contrast to conventional control methods,which either show a limited performance,such as proportional integral differential(PID)control,or which purely focus on mathematical optimality as classical optimal control approaches,our proposed AI approach redefines the objective of control for achieving practical optimality.This presented AI controller minimizes the root-mean-square control deviations in routine scans by a factor of about 4 compared to PID control in the presented setup and also showcases a distinctive asymmetric response in complex situations,prioritizing the safety of the AFM tip and sample instead of the lowest possible control deviations.The development and testing of the AI control concept are performed on simulated AFM scans,demonstrating its huge potential.

一种新型的高频半导体量子点单电子泵

除了直流负电压外,还在浅法刻蚀出的GaAs/AlGaAs量子线上的两个金属指形门上分别叠加两个相位相差π的正弦信号,从而对形成量子点的两个势垒作不等幅调制.在无源漏偏压的情况下,通过周期形成的量子点实现了单电子的搬运.由于新的半导体量子点单电子泵不是依赖库仑阻塞效应通过隧穿进行单电子输运,因此,该器件就不会受到固定隧穿时间引起的低工作频率限制.在1.7K温度下,频率达到3GHz仍然可以观测到量子化电流平台,对应的电流值达到0.5nA量级.这种新器件提供了实现高速度、高精度搬运单电子的另一种可能途径.

^15N(p,n)^15O反应中子源0°角激发函数测量

利用中国原子能科学研究院HI-13串列加速器上的多探测器快中子飞行时间谱仪,测量了38个不同入射质子能量点下15N(p,n)15O反应0°角方向的激发函数。测量数据用蒙特卡罗方法进行了模拟,以进行中子注量衰减和入射窗厚度的不确定度修正。实验在入射质子能量位于6.029—8.056 MeV之间时发现了3个共振峰,这一点与DROSG-2000评价数据及PTB数据相符合,但三家的截面数值存在差异,对这些差异需要作进一步深入探讨。

单频干涉仪瞬时相位计算的神经网络模型

用反三角函数表述的单频干涉仪瞬时相位的解析计算模型通常是分段或不连续的,不利于系统性能的综合分析.这里提出了基于神经网络的干涉仪瞬时相位的连续型计算模型,给出了网络学习方法.仿真研究结果表明,该模型对干涉仪瞬时相位的辨识精度优于0.5°,同时对干涉仪的光强波动有良好的鲁棒性;实验结果验证了这一点,为进一步提高单频干涉仪信号处理精度奠定了基础.此外,简要述及了该模型在其他测量领域,特别是速度-加速度测量领域的应用前景.

Comparison of EUV Photomask Metrology Between CD-AFM and TEM

Accurate metrology of extreme ultraviolet (EUV) photomask is a crucial task. In this paper, two different methods for reference EUV photomask metrology are compared. One is the critical dimension atomic force microscopy (CD-AFM). In the measurements, the contribution of its AFM tip geometry is usually the dominant error source, as measured AFM images are the dilated results of measured structures by the AFM tip geometry. To solve this problem, a bottom-up approach has been applied in calibrating the (effective) AFM tip geometry where the result is traceably calibrated to the lattice constant of silicon crystals. The other is transmission electron microscopy (TEM). For achieving measurement traceability, structure features are measured in pairs in TEM images;thus the distance between the structure pair calibrated by a metrological AFM in prior can be applied to determine the magnification of the TEM image. In this study, selected photomask structures are calibrated by the CD-AFM, and then sample prepared and measured by high-resolution TEM nearly at the same location. The results are then compared. Of six feature groups compared, the results agree well within the measurement uncertainty, indicating excellent performance of the developed methodology. This research supports the development of a photomask standard, which is applied as a “reference ruler” with improved low measurement uncertainty in photomask fabs.

Near-field holography enhanced with antireflection coatings--an improved method for fabricating diffraction gratings

Near-field holography（NFH）, with its virtues of precise critical dimensions and high throughput, has a great potential for the realization of soft x-ray diffraction gratings. We show that NFH with reflections reduced by the integration of antireflective coatings（ARCs） simplifies the NFH process relative to that of setups using refractive index liquids. Based on the proposed NFH with ARCs, gold-coated laminar gratings were fabricated using NFH and subsequent ion beam etching. The efficiency angular spectrum shows that the stray light of the gratings is reduced one level of magnitude by the suppression of interface reflections during NFH.

Free-space interferometer design for optical frequency dissemination and out-of-loop characterization below the 10^(-21)-level

For improving the performance of optical frequency dissemination and the resolution of its out-of-loop(OOL)characterization,we investigate a compact free-space interferometer design in which a monolithic assembly forms the reference arm.Two interferometer designs are realized,and their environmental sensitivity is analyzed based on the properties of the materials involved.We elucidate that in these designs the temperature sensitivities of the out-of-loop signal paths are greater than for the reference arm.As the estimated temperature-variation-induced frequency transfer errors are observed to be the relevant limitation,the out-of-loop characterization signal can be regarded as a trustworthy upper limit of the frequency transfer error to a remote place.We demonstrate a fractional frequency transfer uncertainty and OOL characterization resolution of≤2.7×10^(-21)over many measurement runs.With a value of(0.23±1.07)×10^(-22)the weighted mean offset is significantly below the best reported results so far.

Directly addressable GaN-based nano-LED arrays: fabrication and electro-optical characterization

The rapid development of display technologies has raised interest in arrays of self-emitting,individually controlled light sources atthe microscale.Gallium nitride(GaN)micro-light-emitting diode(LED)technology meets this demand.However,the current technology is not suitable for the fabrication of arrays of submicron light sources that can be controlled individually.Our approach is based on nanoLED arrays that can directly address each array element and a self-pitch with dimensions below the wavelength of light.The design and fabrication processes are explained in detail and possess two geometries:a 6×6 array with 400 nm LEDs and a 2×32 line array with 200 nm LEDs.These nanoLEDs are developed as core elements of a novel on-chip super-resolution microscope.GaN technology,based on its physical properties,is an ideal platform for such nanoLEDs.