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165 results on '"Zheng, Yuzhen"'

1. Fabrication of Al/AlOx/Al junctions with high uniformity and stability on sapphire substrates

Author

Zheng, Yuzhen, Li, Shuming, Ding, Zengqian, Xiong, Kanglin, Feng, Jiagui, and Yang, Hui

Subjects
Condensed Matter - Superconductivity, Quantum Physics
Abstract

Tantalum and aluminum on sapphire are widely used platforms for qubits of long coherent time. As quantum chips scale up, the number of Josephson junctions on Sapphire increases. Thus, both the uniformity and stability of the junctions are crucial to quantum devices, such as scalable superconducting quantum computer circuit, and quantum-limited amplifiers. By optimizing the fabrication process, especially, the conductive layer during the electron beam lithography process, Al/AlOx/Al junctions of sizes ranging from 0.0169 to 0.04 {\mu}m2 on sapphire substrates were prepared. The relative standard deviation of room temperature resistances (RN) of these junctions is better than 1.7% on 15 mmx15 mm chips, and better than 2.66% on 2 inch wafers, which is the highest uniformity on sapphire substrates has been reported. The junctions are robust and stable in resistances as temperature changes. The resistances increase by the ratio of 9.73% relative to RN as the temperature ramp down to 4K, and restore their initial values in the reverse process as the temperature ramps back to RT. After being stored in a nitrogen cabinet for 100 days, the resistance of the junctions changed by1.16% in average. The demonstration of uniform and stable Josephson junctions in large area paves the way for the fabrication of superconducting chip of hundreds of qubits on sapphire substrates.

Published
2023
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3. Large-scale full-programmable quantum walk and its applications

Author

Wang, Yizhi, Liu, Yingwen, Zhan, Junwei, Xue, Shichuan, Zheng, Yuzhen, Zeng, Ru, Wu, Zhihao, Wang, Zihao, Zheng, Qilin, Wang, Dongyang, Shi, Weixu, Fu, Xiang, Xu, Ping, Wang, Yang, Liu, Yong, Ding, Jiangfang, Huang, Guangyao, Yu, Chunlin, Huang, Anqi, Qiang, Xiaogang, Deng, Mingtang, Xu, Weixia, Lu, Kai, Yang, Xuejun, and Wu, Junjie

Subjects
Quantum Physics, Computer Science - Emerging Technologies, Physics - Optics
Abstract

With photonics, the quantum computational advantage has been demonstrated on the task of boson sampling. Next, developing quantum-enhanced approaches for practical problems becomes one of the top priorities for photonic systems. Quantum walks are powerful kernels for developing new and useful quantum algorithms. Here we realize large-scale quantum walks using a fully programmable photonic quantum computing system. The system integrates a silicon quantum photonic chip, enabling the simulation of quantum walk dynamics on graphs with up to 400 vertices and possessing full programmability over quantum walk parameters, including the particle property, initial state, graph structure, and evolution time. In the 400-dimensional Hilbert space, the average fidelity of random entangled quantum states after the whole on-chip circuit evolution reaches as high as 94.29$\pm$1.28$\%$. With the system, we demonstrated exponentially faster hitting and quadratically faster mixing performance of quantum walks over classical random walks, achieving more than two orders of magnitude of enhancement in the experimental hitting efficiency and almost half of the reduction in the experimental evolution time for mixing. We utilize the system to implement a series of quantum applications, including measuring the centrality of scale-free networks, searching targets on Erd\"{o}s-R\'{e}nyi networks, distinguishing non-isomorphic graph pairs, and simulating the topological phase of higher-order topological insulators. Our work shows one feasible path for quantum photonics to address applications of practical interests in the near future.

Published
2022

4. High-suppression-ratio and wide bandwidth four-stage Purcell filter for multiplexed superconducting qubit readout.

Author

Zhou, Yibiao, Cai, Xiao, Zheng, Yuzhen, Zhou, Boyi, Wang, Yu, Xiong, Kanglin, and Feng, Jiagui

Subjects
QUBITS, SPATIAL arrangement, BANDWIDTHS, ELECTROMAGNETIC radiation, SCALABILITY, SUPERCONDUCTING quantum interference devices
Abstract

Purcell filters, which serve to suppress electromagnetic radiation and enhance the readout efficiency of qubit, are an indispensable component in superconducting quantum chips. With the increasing scale of quantum chips, the requirements for the performance and scalability of Purcell filters are becoming more stringent. In this report, a novel four-stage Purcell filter that enables fast measurement without exacerbating environmental damping of the qubits is presented. The design approach of the filter is derived from the serial and parallel configurations of λ/4 resonant cavities. The filter exhibits exceptional passband-to-stopband isolation, reaching up to 40 dB of isolation within the transition range of 400 MHz. Furthermore, the filter boasts a wide bandwidth for both the stopband and the passband, with the stopband ranging from 4 to 5.5 GHz and the passband extending from 5.8 to 6.5 GHz. In terms of spatial arrangement, each filter can be connected to over ten readout resonators for qubit readout. This innovative Purcell filter will significantly contribute to the development of high quality, scalable superconducting quantum chips. [ABSTRACT FROM AUTHOR]

Published
2024
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21. Fabrication of Al/AlOx/Al junctions with high uniformity and stability on sapphire substrates.

Author

Zheng, Yuzhen, Li, Shuming, Ding, Zengqian, Xiong, Kanglin, Feng, Jiagui, and Yang, Hui

Subjects
*SAPPHIRES, *ELECTRON beam lithography, *JOSEPHSON junctions, *COMPUTER circuits, *UNIFORMITY, *QUANTUM computers, *ZINC oxide films
Abstract

Tantalum and aluminum on sapphire are widely used platforms for qubits of long coherent time. As quantum chips scale up, the number of Josephson junctions on sapphire increases. Thus, both the uniformity and stability of the junctions are crucial to quantum devices, such as scalable superconducting quantum computer circuit, and quantum-limited amplifiers. By optimizing the fabrication process, especially, the conductive layer during the electron beam lithography process, Al/AlOx/Al junctions of sizes ranging from 0.0169 to 0.04 µm2 on sapphire substrates were prepared. The relative standard deviation of room temperature resistances (RN) – σ R N / R N of these junctions is better than 1.7% on 15 mm × 15 mm chips, and better than 2.66% on 2 inch wafers, which is the highest uniformity on sapphire substrates has been reported. The junctions are robust and stable in resistances as temperature changes. The resistances increase by the ratio of 9.73% relative to RN as the temperature ramp down to 4 K, and restore their initial values in the reverse process as the temperature ramps back to room temperature. After being stored in a nitrogen cabinet for 100 days, the resistance of the junctions changed by1.16% on average. The demonstration of uniform and stable Josephson junctions in large area paves the way for the fabrication of superconducting chip of hundreds of qubits on sapphire substrates. [ABSTRACT FROM AUTHOR]

Published
2023
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29. Micropollutant abatement by the UV/chloramine process in potable water reuse: A review

Author

Cao, Zhenfeng, Yu, Ximing, Zheng, Yuzhen, Aghdam, Ehsan, Sun, Bo, Song, Mingming, Wang, Aijie, Han, Jinglong, Zhang, Jian, Cao, Zhenfeng, Yu, Ximing, Zheng, Yuzhen, Aghdam, Ehsan, Sun, Bo, Song, Mingming, Wang, Aijie, Han, Jinglong, and Zhang, Jian

Abstract

The need in using reclaimed water increased significantly to address the water shortage and its continuing quality deterioration in sustaining societal development. Degrading micropollutants in wastewater treatment plant effluents is one of the most important tasks in supplying safe drinking water, which is often achieved by full advanced treatment technologies (FATs), including reverse osmosis (RO) and the UV-based advanced oxidation process (AOP). As an emerging AOP, UV/chloramine process shows many noteworthy advantages in the scenario of potable water reuse, including membrane biological fouling control by chloramine, producing highly reactive radicals (e.g., Cl•, HO•, Cl2•–, and reactive nitrogen-containing species) to degrade the RO permeated pollutants, and acting as long-lasting disinfectant in the potable water distribution system. In addition, chloramine is often designedly produced by taking advantage of the ammonia in source. Thus, UV/chloramine processes gather much attention from researcher and published papers on UV/chloramine process have drastically increased since 2016, which were thoroughly reviewed in this paper. The fundamentals of chloramine photolysis, including the photolysis kinetics, the quantum yield, the generation and transformation of radicals and the final products, were scrutinized. Further, the impacts of reaction conditions such as pH, chloramine dosage and water matrix on the degradation of micropollutants by the UV/chloramine process are discussed. Moreover, the formation potential of disinfection by-products is debated. The opportunity of application of the UV/chloramine process in real-world practice is also presented, emphasizing the need for extensive efforts to remove currently prevalent knowledge roadblocks. © 2021 Elsevier B.V.

Published
2022

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