News on China's scientific and technological development.

Quantum Interference between Nonidentical Single Particles​

Abstract​

Quantum interference between identical single particles reveals the intrinsic quantum statistic nature of particles, which could not be interpreted through classical physics. Here, we demonstrate quantum interference between nonidentical bosons using a generalized beam splitter based on a quantum memory. The Hong-Ou-Mandel type interference between single photons and single magnons with high visibility is demonstrated, and the crossover from the bosonic to fermionic quantum statistics is observed by tuning the beam splitter to be non-Hermitian. Moreover, multiparticle interference that simulates the behavior of three fermions by three input photons is realized. Our work extends the understanding of the quantum interference effects and demonstrates a versatile experimental platform for studying and engineering quantum statistics of particles.


本报讯（记者朱汉斌）华南师范大学物理与电信工程学、物理前沿科学研究院、粤港量子物质联合实验室的冷原子研究团队在量子科技方面取得新研究进展，首次实验实现了不同粒子之间的量子干涉。该成果日前发表于《物理评论快报》。

相同粒子之间的量子干涉可以揭示粒子固有的量子统计特性，这在经典物理学范畴内无法得到合理解释，从而引起物理学家们的研究兴趣。分束器是实现量子干涉的核心元件，全同粒子输入分束器后，在输出端口可形成量子纠缠态，该量子纠缠态便是全同粒子干涉后的结果。同类型的玻色子，如光子与光子、磁子与磁子、等离激元与等离激元之间的量子干涉早已得到了广泛和深入的研究。然而到目前为止，尚未有研究组对不同类型的玻色子之间的量子干涉行为进行过研究。

在该项研究中，研究人员利用量子存储器在实验上实现了非厄密分束器，演示了不同类型玻色子之间的量子干涉。该实验首先通过调节量子存储过程中控制光失谐与拉比频率，实现了分束器从厄密到非厄密特性的连续切换，然后通过调节分束器的非厄密性质，观测到了单磁子与单光子干涉从玻色子到费米子量子统计的转变。最后，通过连续输入3个单光子进入非厄密分束器实现了三光子干涉。该工作扩展了人们对量子干涉效应的理解，展示了一个可用于研究粒子量子统计行为的多功能实验平台。

审稿人指出，这项有意义的成果有望应用于量子干涉相关的量子技术中，包括量子通信、量子测量与传感及量子计算等。

siegecrossbow said:

Stephen is scarcely better than Minnie Chan. He probably took things out of context to get clicks.

Click to expand...

He did. The more you read that fusion article the more you realise that

This report finds the following:
• The most prominent recent expression of China’s broader goals in international standardization are found in the “National Standardization Development Outline” (国家标准化发展纲要), which is the culmination of a years-long project called “China Standards 2035.”
• The Outline characterizes standardization as a means to reinforce national comprehensive competitiveness and expedite economic and social development and stresses its value in advancing China’s economic development, supporting technological innovation, “opening up” China to the world, and—less explicitly— bolstering national security.
• The Outline and “China Standards 2035” emphasize a number of methods for turning Chinese aspirations to influence and shape global technical standards into concrete reality. Official sources encourage active participation in the International Standardization Organization (ISO), International Electrotechnical Commission (IEC), and International Telecommunication Union (ITU), proposing more work
items, forming new organizations, and accelerating internationalization of Chinese technical standards in new energy, new materials, quantum computing, smart manufacturing, industrialized construction, and engineering
• China’s disproportionately high – and increasing – rate of participation in ITU-T through Contributions and Work Items is particularly notable in contrast with ISO, where no single country is as dominant as China is in ITU. China takes advantage of non-competitive opportunities for participation to dominate the system through number of leadership positions held and sheer number of proposals. In the
aggregate, the figures for both have increased over the last decade.
• Available ISO reports indicate that Chinese presence in the body has increased both in terms of the number of secretariats and convenorships over the past decade, but China’s progress in ISO standards formation is comparatively untracked, as ISO does not provide either country-of-origin or country-specific authorship or editorship information.
• Overall, China has attempted to steer the standardization of emerging technology areas through quantitative dominance of leadership positions and number of Work Items, especially in ITU. Perhaps more notable, however, for many of these technologies, China has arguably asserted influence not in number of recommendations but in importance by steering foundational standards work in roadmaps, overviews, reference architectures, terminologies, and general specifications

Paper (preview) in English:

Femtosecond laser writing of lithium niobate ferroelectric nanodomains​

Abstract​

Lithium niobate (LiNbO3) is viewed as a promising material for optical communications and quantum photonic chips,. Recent breakthroughs in LiNbO3 nanophotonics have considerably boosted the development of high-speed electro-optic modulators,,, frequency combs, and broadband spectrometers. However, the traditional method of electrical poling for ferroelectric domain engineering in optic,,,,, acoustic,,, and electronic applications, is limited to two-dimensional space and micrometre-scale resolution. Here we demonstrate a non-reciprocal near-infrared laser-writing technique for reconfigurable three-dimensional ferroelectric domain engineering in LiNbO3 with nanoscale resolution. The proposed method is based on a laser-induced electric field that can either write or erase domain structures in the crystal, depending on the laser-writing direction. This approach offers a pathway for controllable nanoscale domain engineering in LiNbO3 and other transparent ferroelectric crystals, which has potential applications in high-efficiency frequency mixing,, high-frequency acoustic resonators,,, and high-capacity non-volatile ferroelectric memory,.

News report in Chinese:

我国科学家首次获得纳米级光雕刻三维结构​

14日夜，国际顶级学术期刊《自然》发表了我国科学家在下一代光电芯片制造领域的重大突破。南京大学张勇、肖敏、祝世宁领衔的科研团队，发明了一种新型“非互易飞秒激光极化铁电畴”技术，将飞秒脉冲激光聚焦于材料“铌酸锂”的晶体内部，通过控制激光移动的方向，在晶体内部形成有效电场，实现三维结构的直写和擦除。

这一新技术，突破了传统飞秒激光的光衍射极限，把光雕刻铌酸锂三维结构的尺寸，从传统的1微米量级（相当于头发丝的五十分之一），首次缩小到纳米级，达到30纳米，大大提高了加工精度。

这一重大发明，未来或可开辟光电芯片制造新赛道，有望用于光电调制器、声学滤波器、非易失铁电存储器等关键光电器件芯片制备，在5G/6G通讯、光计算、人工智能等领域有广泛的应用前景。

Picotesla magnetometry of microwave fields with diamond sensors​

Abstract​

Developing robust microwave-field sensors is both fundamentally and practically important with a wide range of applications from astronomy to communication engineering. The nitrogen vacancy (NV) center in diamond is an attractive candidate for such purpose because of its magnetometric sensitivity, stability, and compatibility with ambient conditions. However, the existing NV center–based magnetometers have limited sensitivity in the microwave band. Here, we present a continuous heterodyne detection scheme that can enhance the sensor’s response to weak microwaves, even in the absence of spin controls. Experimentally, we achieve a sensitivity of 8.9 pT Hz−1/2 for microwaves of 2.9 GHz by simultaneously using an ensemble of nNV ~ 2.8 × 1013 NV centers within a sensor volume of 4 × 10−2 mm3. Besides, we also achieve 1/t scaling of frequency resolution up to measurement time t of 10,000 s. Our scheme removes control pulses and thus will greatly benefit practical applications of diamond-based microwave sensors.

我科学家实现高灵敏测量高频微波​

日前，中国科学技术大学中科院微观磁共振重点实验室杜江峰、石发展、孔飞等人在微波磁场测量领域取得重要进展，基于金刚石氮-空位色心量子传感器实现了皮特斯拉水平的高灵敏微波磁场测量，相比此前该体系实现的亚微特斯拉指标水平，测量灵敏度提升了近十万倍。相关研究成果发表于《科学进展》。

微波在人类生活和科学研究中无处不在。日常生活中，移动通信所使用的电磁波便属于微波范畴，发展微波测量技术对无线通信的发展有重要价值。科学研究中，实现对高频微波的高灵敏测量能够为高场高频磁共振谱学、太赫兹成像甚至天文学观测提供基础支撑。

利用从原理上革新的量子传感技术能够大大提升微波的测量灵敏度，这在过去的十几年中得到广泛研究和发展。目前，常见的量子传感器包括里德堡原子、原子磁力计、超导量子干涉仪、金刚石NV色心等。其中NV色心体系因独特的载体稳定性和室温大气环境兼容性，成为极具发展前景的固态量子传感器，提升探测灵敏度是最重要的发展方向之一。

提升灵敏度最直接的途径是利用大量NV色心开展并行测量。由于单个NV色心的尺寸只有原子级，因此即使是毫米级芯片大小的金刚石中也可以集成数以亿万计的NV色心。但是随着尺寸的增加，对所有的NV色心同步地进行量子调控变得更加困难。

因此，研究人员提出一种无须复杂量子调控的测量方案，大幅地提高金刚石中NV色心的利用率。其基本原理是NV色心在激光的连续激发下会持续产生荧光，当空间中存在一个与NV色心能级共振的弱微波时，荧光亮度会下降，下降幅度与微波幅度的平方成正比，也就是说当待测微波很弱时，荧光的响应极其微弱。

为提升NV色心对微波的响应，研究团队借鉴传统外差测量的思路，提出了连续外差微波探测方法：引入一个稍强的辅助微波与被测微波干涉，产生拍频振荡，相应的NV荧光也会产生频率为拍频振荡，其振幅与待测微波幅度成正比，相当于用辅助微波“放大”了待测微波。

利用该方法，研究团队在体积为0.04立方毫米包含2.8*1013个NV色心的金刚石量子传感器上成功实现了单位时间灵敏度为8.9皮特斯拉的微波磁场测量，相比此前该体系实现的亚微特斯拉指标水平，测量灵敏度提升了近十万倍。

该方法避免了复杂的同步量子操控，可以直接推广到包含更多NV色心的更大体积的金刚石量子传感器上，未来有望将测量灵敏度进一步提升至0.1皮特斯拉水平量级甚至更高。由于省去了与量子操控配套的硬件装置，该方案为金刚石量子传感系统的小型化和芯片化奠定基础。同时也向着金刚石量子传感器在无线通信、磁共振检测等领域的实用化迈出重要一步。

Tunable quantum criticalities in an isospin extended Hubbard model simulator​

Abstract​

Studying strong electron correlations has been an essential driving force for pushing the frontiers of condensed matter physics. In particular, in the vicinity of correlation-driven quantum phase transitions (QPTs), quantum critical fluctuations of multiple degrees of freedom facilitate exotic many-body states and quantum critical behaviours beyond Landau’s framework. Recently, moiré heterostructures of van der Waals materials have been demonstrated as highly tunable quantum platforms for exploring fascinating, strongly correlated quantum physics,,,,,,,,,,,,,,,,,,,,. Here we report the observation of tunable quantum criticalities in an experimental simulator of the extended Hubbard model with spin–valley isospins arising in chiral-stacked twisted double bilayer graphene (cTDBG). Scaling analysis shows a quantum two-stage criticality manifesting two distinct quantum critical points as the generalized Wigner crystal transits to a Fermi liquid by varying the displacement field, suggesting the emergence of a critical intermediate phase. The quantum two-stage criticality evolves into a quantum pseudo criticality as a high parallel magnetic field is applied. In such a pseudo criticality, we find that the quantum critical scaling is only valid above a critical temperature, indicating a weak first-order QPT therein. Our results demonstrate a highly tunable solid-state simulator with intricate interplay of multiple degrees of freedom for exploring exotic quantum critical states and behaviours.

我国科学家实现量子模拟领域新突破​

昨夜（14日夜11时），国际学术期刊《自然》在线发表了我国科学家在量子模拟前沿领域的新突破。南京大学缪峰合作团队通过在“原子世界搭积木”的方式，把两个石墨烯双原子层，以旋转180度+0.75度的特殊角度叠加，并施加一个垂直电场，研制出一种全新的量子材料，并通过改变垂直电场，在国际物理学界首次观测到了量子融化的“中间态”，并揭示了这一量子“中间态”的演化机制。

这一重大理论机制的创新成果，未来有望用于开发高密度集成、高度可调和易于读取的固体量子模拟器，例如通过模拟生物神经网络、化学反应系统等复杂体系的演化，用于类脑人工智能技术开发和新药研发等。

Abstract​

Noncontact interactive technology provides an intelligent solution to mitigate public health risks from cross-infection in the era of COVID-19. The utilization of human radiation as a stimulus source is conducive to the implementation of low-power, robust noncontact human–machine interaction. However, the low radiation intensity emitted by humans puts forward a high demand for photodetection performance. Here, a SrTiO3−x/CuNi-heterostructure-based thermopile is constructed, which features the combination of high thermoelectric performance and near-unity long-wave infrared absorption, to realize the self-powered detection of human radiation. The response level of this thermopile to human radiation is orders of magnitude higher than those of low-dimensional-materials-based photothermoelectric detectors and even commercial thermopiles. Furthermore, a touchless input device based on the thermopile array is developed, which can recognize hand gestures, numbers, and letters in real-time. This work offers a reliable strategy to integrate the spontaneous human radiation into noncontact human–machine interaction systems.


近日，中国科学院大连化学物理研究所副研究员陆晓伟、研究员姜鹏及中国科学院院士包信和团队，在高灵敏、低功耗人体红外热辐射探测器研制及其在非接触人机交互系统中的应用方面取得新进展。相关研究成果发表于《先进材料》。

人体自发热辐射主要位于长波红外波段，呈现出光子能量低、光强弱等特点。实现人体红外热辐射的高灵敏探测，对构建低功耗、非接触人机交互系统具有重要意义。作为一种热敏型探测器，光热电探测器是基于光热转换、热电转换两个能量转换过程，具有光谱响应范围宽、无须制冷、功耗低等优点。目前，商业的光热电探测器通常采用分立式的热电堆结构，需要复杂的微机电系统机械加工制备工艺，且在探测人体热辐射时，其输出电压相对较小（数十至数百微伏），需要额外的高信噪比信号采集电路。

在该研究中，团队突破传统热电堆材料和构架的限制，构建了基于SrTiO3-x/CuNi异质界面结构的一体式热电堆，在探测人体辐射时展现出高灵敏度、低噪音、高稳定性等特征，其输出电压最高可达13毫伏，相比商业热电堆有数量级的提升。通过进一步构建热电堆阵列，团队还实现了实时手势识别、非接触式数字/字母输入等功能。

该研究为开发低功耗非接触人机交互系统提供了新思路，在人工智能、公共卫生安全领域具有广阔的实际应用价值。

WIPO Global Innovation Index- World's top 10 Science and technology Clusters.

1. Tokyo

2. Shenzhen-Guangzhou-HK

3. Beijing

4. Seoul

5. San Jose - SF

6. Shanghai-Suzhou

7. Osaka-Kobe-Kyoto

8. Boston - Cambridge

9. New York City

10. Paris