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Quantum transport quality of a processed undoped Ge/SiGe heterostructure

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Physical review B 2023年第4期108卷 045303-045303页

作者： Yi-Xin Li Zhenzhen Kong Shimin Hou Guilei Wang Shaoyun Huang Beijing Key Laboratory of Quantum Devices Key Laboratory for the Physics and Chemistry of Nanodevices Peking University Beijing 100871 People's Republic of China Integrated Circuit Advanced Process R&D Center Institute of Microelectronics Chinese Academy of Sciences Beijing 100029 People's Republic of China School of Integrated Circuits University of Chinese Academy of Sciences Beijing 100049 People's Republic of China Hefei National Laboratory Hefei 230088 People's Republic of China and Beijing Superstring Academy of Memory Technology Beijing 100176 People's Republic of China

A degraded mobility of 5.2×105cm2V−1s−1 but a long quantum scattering time of 2.3 ps at the hole density of 2.25×1011cm−2 were obtained from a two-dimensional hole gas in a processed undoped Ge/SiGe heterostructure Hall-bar field-effect device. The heterostructure was grown by the reduced pressure chemical vapor deposition method and the device fabrications were compatible with well-established semiconductor technology. The percolation density of 0.69×1011cm−2 indicated a very low disorder potential landscape experienced by holes in the strained Ge quantum well. In addition to integer quantum Hall effects (IQHEs) of consecutive filling factors from ν=8 down to 1, we also observed the quantum states at filling factors between ν=1 and 2, and between ν=2 and 3 at 1.71 K. The observation of quantum Hall effects at the inferior mobility confirmed the mobility/quality dichotomy in the ultraclean undoped Ge/SiGe heterostructure. The study explicitly indicated that the device fabrication process likely compromised the transport mobility, whereas the quantum quality was less influenced, and established the heterostructure as an ideal platform for quantum device implementations.

关键词： Electrical properties Fractional quantum Hall effect Quantum Hall effect Quantum wells Two-dimensional electron system Epitaxy Hall bar Methods in transport Shubnikov-de Haas effect

Singlet-triplet-state readout in silicon metal-oxide-semiconductor double quantum dots

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Physical review Applied 2024年第3期21卷 034022-034022页

作者： rong-Long Ma Sheng-Kai Zhu Zhen-Zhen Kong Tai-Ping Sun Ming Ni Yu-Chen Zhou Yuan Zhou Gang Luo Gang Cao Gui-Lei Wang Hai-Ou Li Guo-Ping Guo CAS Key Laboratory of Quantum Information University of Science and Technology of China Hefei Anhui 230026 China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of China Hefei Anhui 230026 China Integrated Circuit Advanced Process R&D Center Institute of Microelectronics Chinese Academy of Sciences Beijing 100029 China Hefei National Laboratory University of Science and Technology of China Hefei 230088 China Beijing Superstring Academy of Memory Technology Beijing 100176 China Origin Quantum Computing Company Limited Hefei Anhui 230026 China

High-fidelity singlet-triplet state readout is essential for large-scale quantum computing. However, the widely used threshold method of comparing a mean value with the fixed threshold will limit the judgment accuracy, especially for the relaxed triplet state, under the restriction of relaxation time and signal-to-noise ratio. Here, we achieve an enhanced latching readout based on Pauli spin blockade in a Si-MOS double quantum dot device and demonstrate an average singlet-triplet-state readout fidelity of 97.59% by the threshold method. We reveal the inherent deficiency of the threshold method for the relaxed triplet-state classification and introduce machine learning as a noise-resilient and relaxation-independent readout method to reduce the misjudgment. The readout fidelity for classifying the simulated single-shot traces can be improved to 99.67% by the machine-learning method, better than the threshold method of 97.54%, which is consistent with the experimental result. This work indicates that the machine-learning method can be a strong potential candidate for alleviating the restrictions of stably achieving high-fidelity and high-accuracy singlet-triplet-state readout in large-scale quantum computing.

关键词： Optoelectronics Quantum information with solid state qubits Quantum measurements radio frequency techniques Spin blockade double quantum dots Elemental semiconductors Machine learning

Undoped Strained Ge Quantum Well with Ultrahigh Mobility Grown by reduce Pressure Chemical Vapor deposition

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arXiv 2022年

作者： Kong, Zhenzhen Li, Zonghu Cao, Gang Su, Jiale Zhang, Yiwen Liu, Jinbiao Liu, Jingxiong ren, Yuhui Wei, Laiming Guo, Guoping Wu, Yuanyuan radamson, Henry H. Li, Junfeng Wu, Zhenhua Li, Haiou Yang, Jiecheng Zhao, Chao Wang, Guilei Integrated Circuit Advanced Process R&D Center Institute of Microelectronics Chinese Academy of Sciences Beijing100029 China School of Integrated Circuits University of Chinese Academy of Sciences Beijing100049 China CAS Key Laboratory of Quantum Information University of Science and Technology of China Hefei230026 China Hefei National Laboratory Hefei230088 China School of Advanced Manufacturing Engineering Hefei University Hefei230601 China Origin Quantum Computing Company Limited Hefei230026 China Research and Development Center of Optoelectronic Hybrid IC Guangdong Greater Bay Area Institute of Integrated Circuit and System Guangzhou510535 China Beijing Superstring Academy of Memory Technology 100176 China

We fabricate an undoped Ge quantum well under a 30 nm relaxed Ge0.8Si0.2 shallow barrier. The bottom barrier contains Ge0.8Si0.2 (650 ℃) followed by Ge0.9Si0.1 (800 ℃) such that variation of Ge content forms a sharp interface that can suppress the threading dislocation density (Tdd) penetrating into the undoped Ge quantum well. The Ge0.8Si0.2 barrier introduces enough in-plane parallel strain (Ε strain -0.41%) in the Ge quantum well. The heterostructure field-effect transistors with a shallow buried channel obtain an ultrahigh two-dimensional hole gas (2dHG) mobility over 2×106 cm2/Vs and a very low percolation of 5.625 × 1010cm−2. A tunable fractional quantum Hall effect at high densities and high magnetic fields has also been observed. This approach defines strained germanium as providing the material basis for tuning the spin-orbit coupling strength for fast and coherent quantum *** Codes 81-05, 81V70 © 2022, CC BY-NC-Nd.

关键词： Germanium

Stochastic EUV resist Model

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Stochastic EUV Resist Model

Electronics design Automation (ISEdA), International Symposium of

作者： Guangjian He Jing Xue Taian Fan Yayi Wei Computational Lithography R&D Center Guangdong Greater Bay Area Institute of Integrated Circuit and System Guangzhou China Achievement Transformation Department Institute of Microelectronics Chinese Academy of Sciences Beijing China School of Integrated Circuits Electrical and Communication Engineering University of Chinese Academy of Sciences Beijing China Advanced Semiconductor Technology Development Department Institute of Microelectronics Chinese Academy of Sciences Beijing China

The stochastic effects in photoresist patterning is of great concern in the implementation of EUV lithography. The stochastic nature of EUV chemically amplified resist requires new modeling approaches rather than the continuous model used in dUV. In this paper, a stochastic model based on Gillespie algorithm is introduced, which subdivides the resist volume into many rectangular small cells and simulates the reaction-diffusion behavior of molecules in a cell volume according to carefully calculated probability. In addition, we further explore the influence of the cell size on the stochastic model. There is an optimal cell size in consideration of precision and running time. When cell size is sufficiently large, the results will approximate to the continuous model.

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Single-spin-qubit geometric gate in a silicon quantum dot

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Physical review Applied 2024年第1期21卷 014044-014044页

作者： rong-Long Ma Ao-ran Li Chu Wang Zhen-Zhen Kong Wei-Zhu Liao Ming Ni Sheng-Kai Zhu Ning Chu Chengxian Zhang di Liu Gang Cao Gui-Lei Wang Hai-Ou Li Guo-Ping Guo CAS Key Laboratory of Quantum Information University of Science and Technology of China Hefei Anhui 230026 China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of China Hefei Anhui 230026 China Integrated Circuit Advanced Process R&D Center Institute of Microelectronics Chinese Academy of Sciences Beijing 100029 China School of Physical Science and Technology Guangxi University Nanning 530004 China Hefei National Laboratory University of Science and Technology of China Hefei 230088 China Beijing Superstring Academy of Memory Technology Beijing 100176 China Origin Quantum Computing Company Limited Hefei Anhui 230026 China

Preserving qubit coherence and maintaining high-fidelity qubit control under complex noise environment is an enduring challenge for scalable quantum computing. Here we demonstrate an addressable fault-tolerant single spin qubit with an average control fidelity of 99.12% via randomized benchmarking on a silicon quantum dot device with an integrated micromagnet. Its dephasing time T2∗ is 1.025μs, and can be enlarged to 264μs by using the Hahn-echo technique, reflecting strong low-frequency noise in our system. To break through the noise limitation, we introduce geometric quantum computing to obtain high control fidelity by exploiting its noise-resilient feature. However, the control fidelities of the geometric quantum gates are lower than 99%. According to our simulation, the noise-resilient feature of geometric quantum gates is masked by the heating effect. With further optimization to alleviate the heating effect, geometric quantum computing can be a potential approach to reproducibly achieving high-fidelity qubit control in a complex noise environment.

关键词： Geometric & topological phases Quantum gates Quantum information with solid state qubits Elemental semiconductors Quantum dots Single-electron transistors Electron dipole spin resonance Microwave techniques

Correcting on-chip distortion of control pulses with silicon spin qubits

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arXiv 2023年

作者： Ni, Ming Ma, rong-Long Kong, Zhen-Zhen Chu, Ning Liao, Wei-Zhu Zhu, Sheng-Kai Wang, Chu Luo, Gang Liu, di Cao, Gang Wang, Gui-Lei Li, Hai-Ou Guo, Guo-Ping Cas Key Laboratory of Quantum Information University of Science and Technology of China Anhui Hefei230026 China Cas Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of China Anhui Hefei230026 China Integrated Circuit Advanced Process R&d Center Institute of Microelectronics Chinese Academy of Sciences Beijing100029 China Hefei National Laboratory University of Science and Technology of China Hefei230088 China Beijing Superstring Academy of Memory Technology Beijing100176 China Origin Quantum Computing Company Limited Anhui Hefei230026 China

Pulse distortion, as one of the coherent error sources, hinders the characterization and control of qubits. In the semiconductor quantum dot system, the distortions on measurement pulses and control pulses disturb the experimental results, while no effective calibration procedure has yet been reported. Here, we demonstrate two different calibration methods to calibrate and correct the distortion using the two-qubit system as a detector. The two calibration methods have different correction accuracy and complexity. One is the coarse predistortion (CPd) method, with which the distortion is partly relieved. The other method is the all predistortion (APd) method, with which we measure the transfer function and significantly improve the exchange oscillation homogeneity. The two methods use the exchange oscillation homogeneity as the metric and are appropriate for any qubit that oscillates with a diabatic pulse. With the APd procedure, an arbitrary control waveform can be accurately delivered to the device, which is essential for characterizing qubits and improving gate fidelity. Copyright © 2023, The Authors. All rights reserved.

关键词： Qubits

Singlet-triplet-state readout in silicon-metal-oxide-semiconductor double quantum dots

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arXiv 2023年

作者： Ma, rong-Long Zhu, Sheng-Kai Kong, Zhen-Zhen Sun, Tai-Ping Ni, Ming Zhou, Yu-Chen Zhou, Yuan Luo, Gang Cao, Gang Wang, Gui-Lei Li, Hai-Ou Guo, Guo-Ping CAS Key Laboratory of Quantum Information University of Science and Technology of China Anhui Hefei230026 China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of China Anhui Hefei230026 China Integrated Circuit Advanced Process R&D Center Institute of Microelectronics Chinese Academy of Sciences Beijing100029 China Hefei National Laboratory University of Science and Technology of China Hefei230088 China Beijing Superstring Academy of Memory Technology Beijing100176 China Origin Quantum Computing Company Limited Anhui Hefei230026 China

High-fidelity singlet-triplet state readout is essential for large-scale quantum computing. However, the widely used threshold method of comparing a mean value with the fixed threshold will limit the judgment accuracy, especially for the relaxed triplet state, under the restriction of relaxation time and signal-to-noise ratio. Here, we achieve an enhanced latching readout based on Pauli spin blockade in a Si-MOS double quantum dot device and demonstrate an average singlet-triplet state readout fidelity of 97.59% by the threshold method. We reveal the inherent deficiency of the threshold method for the relaxed triplet state classification and introduce machine learning as a relaxation-independent readout method to reduce the misjudgment. The readout fidelity for classifying the simulated single-shot traces can be improved to 99.67% by machine learning method, better than the threshold method of 97.54% which is consistent with the experimental result. This work indicates that machine learning method can be a strong potential candidate for alleviating the restrictions of stably achieving high-fidelity and high-accuracy singlet-triplet state readout in large-scale quantum computing. Copyright © 2023, The Authors. All rights reserved.

关键词： Semiconductor quantum dots

A diverse set of two-qubit gates for spin qubits in semiconductor quantum dots

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arXiv 2024年

作者： Ni, Ming Ma, rong-Long Kong, Zhen-Zhen Chu, Ning Zhu, Sheng-Kai Wang, Chu Li, Ao-ran Liao, Wei-Zhu Cao, Gang Wang, Gui-Lei Guo, Guang-Can Hu, Xuedong Li, Hai-Ou Guo, Guo-Ping CAS Key Laboratory of Quantum Information University of Science and Technology of China Anhui Hefei230026 China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of China Anhui Hefei230026 China Integrated Circuit Advanced Process R&D Center Institute of Microelectronics Chinese Academy of Sciences Beijing100029 China Department of Physics University at Buffalo SUNY BuffaloNY14260 United States Beijing Superstring Academy of Memory Technology Beijing100176 China Hefei National Laboratory University of Science and Technology of China Hefei230088 China Origin Quantum Computing Company Limited Anhui Hefei230026 China

To realize large-scale quantum information processes, an ideal scheme for two-qubit operations should enable diverse operations with given hardware and physical interaction. However, for spin qubits in semiconductor quantum dots, the common two-qubit operations, including CPhase gates, SWAP gates, and CrOT gates, are realized with distinct parameter regions and control waveforms, posing challenges for their simultaneous implementation. Here, taking advantage of the inherent Heisenberg interaction between spin qubits, we propose and verify a fast composite two-qubit gate scheme to extend the available two-qubit gate types as well as reduce the requirements for device properties. Apart from the formerly proposed CPhase (controlled-phase) gates and SWAP gates, theoretical results indicate that the iSWAP-family gate and Fermionic simulation (fSim) gate set are additionally available for spin qubits. Meanwhile, our gate scheme limits the parameter requirements of all essential two-qubit gates to a common J~∆EZ region, facilitate the simultaneous realization of them. Furthermore, we present the preliminary experimental demonstration of the composite gate scheme, observing excellent match between the measured and simulated results. With this versatile composite gate scheme, broad-spectrum two-qubit operations allow us to efficiently utilize the hardware and the underlying physics resources, helping accelerate and broaden the scope of the upcoming noise intermediate-scale quantum (NISQ) computing. Copyright © 2024, The Authors. All rights reserved.

关键词： Semiconductor quantum dots

Single spin qubit geometric gate in a silicon quantum dot

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arXiv 2023年

作者： Ma, rong-Long Li, Ao-ran Wang, Chu Kong, Zhen-Zhen Liao, Wei-Zhu Ni, Ming Zhu, Sheng-Kai Chu, Ning Zhang, Cheng-Xian Liu, di Cao, Gang Wang, Gui-Lei Li, Hai-Ou Guo, Guo-Ping CAS Key Laboratory of Quantum Information University of Science and Technology of China Anhui Hefei230026 China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of China Anhui Hefei230026 China Integrated Circuit Advanced Process R&D Center Institute of Microelectronics Chinese Academy of Sciences Beijing100029 China School of Physical Science and Technology Guangxi University Nanning530004 China Hefei National Laboratory University of Science and Technology of China Hefei230088 China Beijing Superstring Academy of Memory Technology Beijing100176 China Origin Quantum Computing Company Limited Anhui Hefei230026 China

Preserving qubit coherence and maintaining high-fidelity qubit control under complex noise environment is an enduring challenge for scalable quantum computing. Here we demonstrate an addressable fault-tolerant single spin qubit with an average control fidelity of 99.12 % via randomized benchmarking on a silicon quantum dot device with an integrated micromagnet. Its dephasing time T2∗ is 1.025 µs, and can be enlarged to 264 µs by using the Hahn echo technique, reflecting strong low-frequency noise in our system. To break through the noise limitation, we introduce geometric quantum computing to obtain high control fidelity by exploiting its noise-resilient feature. However, the control fidelities of the geometric quantum gates are lower than 99 %. According to our simulation, the noise-resilient feature of geometric quantum gates is masked by the heating effect. With further optimization to alleviate the heating effect, geometric quantum computing can be a potential approach to reproducibly achieving high-fidelity qubit control in a complex noise environment. Copyright © 2023, The Authors. All rights reserved.

关键词： Qubits