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Optical demonstration of quantum fault-tolerant threshold

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Light(Science & Applications) 2022年第8期11卷 1834-1842页

作者： Kai Sun Ze-Yan Hao Yan Wang Jia-Kun Li Xiao-Ye Xu Jin-Shi Xu yong-jian han Chuan-Feng Li Guang-Can Guo CAS Key Laboratory of Quantum Information University of Science and Technology of ChinaHefei230026China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei230026China Hefei National Laboratory University of Science and Technology of ChinaHefei230088China

A major challenge in practical quantum computation is the ineludible errors caused by the interaction of quantum systems with their environment. Fault-tolerant schemes, in which logical qubits are encoded by several physical qubits, enable to the output of a higher probability of correct logical qubits under the presence of errors. However, strict requirements to encode qubits and operators render the implementation of a full fault-tolerant computation challenging even for the achievable noisy intermediate-scale quantum technology. Especially the threshold for fault-tolerant computation still lacks experimental verification. Here, based on an all-optical setup, we experimentally demonstrate the existence of the threshold for the fault-tolerant protocol. Four physical qubits are represented as the spatial modes of two entangled photons, which are used to encode two logical qubits. The experimental results clearly show that when the error rate is below the threshold, the probability of correct output in the circuit, formed with fault-tolerant gates, is higher than that in the corresponding non-encoded circuit. In contrast, when the error rate is above the threshold, no advantage is observed in the fault-tolerant implementation. The developed high-accuracy optical system may provide a reliable platform to investigate error propagation in more complex circuits with fault-tolerant gates.

关键词： quantum error operators

Dipole–dipole interactions enhance non-Markovianity and protect information against dissipation

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Chinese Physics B 2019年第9期28卷 100-106页

作者： Xiao-Ye Xu Qin-Qin Wang Zhe Chen yong-jian han Chuan-Feng Li Guang-Can Guo Key Laboratory of Quantum Information of Chinese Academy of Sciences (CAS) University of Science and Technology of ChinaHefei 230026China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei 230026China

Preserving non-Markovianity and quantum entanglement from decoherence effect is of theoretical and practical significance in the quantum information processing *** this context, we study a system S that is initially correlated with an ancilla A, which interacts with the environment E via an amplitude damping *** also consider dipole-dipole interactions(DDIs) between the system and ancilla, which are responsible for strong *** investigate the impact of DDIs and detuning on the non-Markovianity and information exchange in different *** show that DDIs are not only better than detuning at protecting the information(without destroying the memory effect) but also induce memory by causing a transition from Markovian to non-Markovian *** contrast, although detuning also protects the information, it causes a transition from non-Markovian to the Markovian *** addition, we demonstrate that the non-Markovianity grows with increasing DDI strength and diminishes with increasing *** also show that the effects of negative detuning and DDIs can cancel out each other, causing a certain loss of coherence and information.

关键词： decoherence non-Markovianity dipole-dipole interactions entanglement

Experimental verification of generalized eigenstate thermalization hypothesis in an integrable system

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Light(Science & Applications) 2022年第7期11卷 1615-1624页

作者： Qin-Qin Wang Si-Jing Tao Wei-Wei Pan Zhe Chen Geng Chen Kai Sun Jin-Shi Xu Xiao-Ye Xu yong-jian han Chuan-Feng Li Guang-Can Guo CAS Key Laboratory of Quantum Information University of Science and Technology of ChinaHefei 230026China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei 230026China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China

Identifying the general mechanics behind the equilibration of a complex isolated quantum system towards a state described by only a few parameters has been the focus of attention in non-equilibrium *** several experimentally unproven conjectures are proposed for the statistical description of quantum(non-)integrable *** plausible eigenstate thermalization hypothesis(ETH),which suggests that each energy eigenstate itself is thermal,plays a crucial role in understanding the quantum thermalization in non-integrable systems;it is commonly believed that it does not exist in integrable ***,integrable systems can still relax to the generalized Gibbs *** a microscopic perspective,understanding the origin of this generalized thermalization that occurs in an isolated integrable system is a fundamental open question lacking experimental ***,we experimentally investigated the spin subsystem relaxation in an isolated spin-orbit coupling quantum *** applying the quantum state engineering technique,we initialized the system with various distribution widths in the mutual eigenbasis of the conserved ***,we compared the steady state of the spin subsystem reached in a long-time coherent dynamics to the prediction of a generalized version of ETH and the underlying mechanism of the generalized thermalization is experimentally verified for the first *** results facilitate understanding the origin of quantum statistical mechanics.

关键词： integrable quantum state

Measuring a dynamical topological order parameter in quantum walks

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Light(Science & Applications) 2020年第1期9卷 1932-1942页

作者： Xiao-Ye Xu Qin-Qin Wang Markus Heyl Jan Carl Budich Wei-Wei Pan Zhe Chen Munsif Jan Kai Sun Jin-Shi Xu yong-jian han Chuan-Feng Li Guang-Can Guo CAS Key Laboratory of Quantum Information University of Science and Technology of ChinaHefei 230026China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei 230026China Max-Planck-Institut fur Physik komplexer Systeme Nöthnitzer Straße 38D-01187 DresdenGermany Institute of Theoretical Physics Technische Universitat Dresden01062 DresdenGermany

Quantum processes of inherent dynamical nature,such as quantum walks,defy a description in terms of an equilibrium statistical physics *** now,identifying the general principles behind the underlying unitary quantum dynamics has remained a key ***,we show and experimentally observe that split-step quantum walks admit a characterization in terms of a dynamical topological order parameter(DTOP).This integer-quantized DTOP measures,at a given time,the winding of the geometric phase accumulated by the wavefunction during a quantum *** observe distinct dynamical regimes in our experimentally realized quantum walks,and each regime can be attributed to a qualitatively different temporal behavior of the *** identifying an equivalent manybody problem,we reveal an intriguing connection between the nonanalytic changes of the DTOP in quantum walks and the occurrence of dynamical quantum phase transitions.

关键词： quantum dynamical topological

Linear optical approach to supersymmetric dynamics

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Chinese Physics B 2020年第1期29卷 300-306页

作者： yong-Tao Zhan Xiao-Ye Xu Qin-Qin Wang Wei-Wei Pan Munsif Jan Fu-Ming Chang Kai Sun Jin-Shi Xu yong-jian han Chuan-Feng Li Guang-Can Guo CAS Key Laboratory of Quantum Information University of Science and Technology of ChinaHefei 230026China Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei 230026China

The concept of supersymmetry developed in particle physics has been applied to various fields of modern *** quantum mechanics,the supersymmetric systems refer to the systems involving two supersymmetric partner Hamiltonians,whose energy levels are degeneracy except one of the systems has an extra ground state possibly,and the eigenstates of the partner systems can be mapped onto each ***,an interferometric scheme has been proposed to show this relationship in ultracold atoms[***.A 96043624(2017)].Here this approach is generalized to linear optics for observing the supersymmetric dynamics with *** time evolution operator is simulated approximately via Suzuki–Trotter expansion with considering the realization of the kinetic and potential terms *** former is realized through the diffraction nature of light and the later is implemented using a phase ***,we propose an interferometric approach which can be implemented perfectly using an amplitude alternator to realize the non-unitary *** numerical results show that our scheme is universal and can be realized with current technologies.

关键词： linear optics supersymmetry quantum simulation

Information protection and enhancement of non-Markovianity via dipole-dipole interaction

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Information protection and enhancement of non-Markovianity v...

A von-Neumann-like photonic processor and its application in studying quantum signature of chaos

第十八届全国量子光学学术会议

作者： Munsif Jan Xiao-Ye Xu yong-jian han Chuan-Feng Li 中国科学技术大学 CAS Key Laboratory of Quantum Information University of Science and Technology of China Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of China

We study the system S initially correlated with ancilla A, which interacts with the environment E by using amplitude damping channel. We also consider dipole-dipole interaction（DDI） between system and ancilla, responsible for strong interaction. Here, we investigate the effect of DDI and detuning on the protection of information as well as the behavior of both Markovian and non-Markovian dynamics. We show that DDI not only protect the information（without destroying the memory effect） better than detuning but also arise the effect of memory in the Markovian regime initially. Whereas the detuning transforms the non-Markovian to the Markovian dynamics during protection. Further, we demonstrate the non-Markovianity increase with increasing DDI and decrease with increasing detuning. Moreover, we also show that negative detuning and DDI can cancel out the effects of each other, along with the loss of some coherence and information. We hope, this trait of DDI prove helpful in the application of quantum technologies.

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来源： cnki会议评论

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Light(Science & Applications) 2024年第4期13卷 672-681页

作者： Shang Yu Wei Liu Si-Jing Tao Zhi-Peng Li Yi-Tao Wang Zhi-Peng Zhong Raj BPatel Yu Meng Yuan-Ze Yang Zhao-An Wang Nai-Jie Guo Xiao-Dong Zeng Zhe Chen Liang Xu Ning Zhang Xiao Liu Mu Yang Wen-Hao Zhang Zong-Quan Zhou Jin-Shi Xu jian-Shun Tang yong-jian han Chuan-Feng Li Guang-Can Guo CAS Key Laboratory of Quantum Information University of Science and Technology of ChinaHefei 230026China. CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei 230026China. Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China. Research Center for Quantum Sensing Zhejiang LabHangzhou 310000China. Quantum Optics and Laser Science Blackett LaboratoryImperial College LondonPrince Consort RdLondon SW72AZUK. Clarendon Laboratory Department of PhysicsOxford UniversityParks Road OX13PUOxfordUK

Photonic quantum computation plays an important role and offers unique *** decades after the milestone work of Knill-Laflamme-Milburn,various architectures of photonic processors have been proposed,and quantum advantage over classical computers has also been *** is now the opportune time to apply this technology to real-world ***,at current technology level,this aim is restricted by either programmability in bulk optics or loss in integrated optics for the existing architectures of processors,for which the resource cost is also a *** we present a von-Neumann-like architecture based on temporal-mode encoding and looped structure on table,which is capable of multimode-universal programmability,resource-efficiency,phasestability and *** order to illustrate these merits,we execute two different programs with varying resource requirements on the same processor,to investigate quantum signature of chaos from two aspects:the signature behaviors exhibited in phase space(13 modes),and the Fermi golden rule which has not been experimentally studied in quantitative way before(26 modes).The maximal program contains an optical interferometer network with 1694 freely-adjustable *** current state-of-the-art,our architecture stands as the most promising candidate for real-world applications.

关键词： quantum signature chaos

Experimental entanglement quantification for unknown quantum states in a semi-device-independent manner

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Science China(Information Sciences) 2023年

作者： Yu GUO Lijinzhi LIN Huan CAO Chao ZhanG Xiaodie LIN Xiao-Min HU Bi-Heng LIU Yun-Feng HUANG Zhaohui WEI yong-jian han Chuan-Feng LI Guang-Can GUO School of Physics and Materials Engineering Hefei Normal University Vienna Center for Quantum Science and Technology Faculty of Physics University of Vienna CAS Center For Excellence in Quantum Information and Quantum Physics University of Science and Technology of China Yau Mathematical Sciences Center Tsinghua University CAS Key Laboratory of Quantum Information University of Science and Technology of China Center for Quantum Information Institute for Interdisciplinary Information Sciences Tsinghua University

Using the concept of non-degenerate Bell inequality, we show that quantum entanglement, the critical resource for various quantum information processing tasks, can be quantified for any unknown quantum state in a semi-device-independent manner, where the quantification is based on the experimentally obtained probability distributions and prior knowledge of the quantum dimension only. Specifically, as an application of our approach to multi-level systems, we experimentally quantify the entanglement of formation and the entanglement of distillation for qutrit-qutrit quantum systems. In addition, to demonstrate our approach for multi-partite systems, we further quantify the geometric measure of entanglement of three-qubit quantum systems. Our results supply a general way to reliably quantify entanglement in multi-level and multi-partite systems, thus paving the way to characterize many-body quantum systems by quantifying the involved entanglement.

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涂层印花儿童纺织品中重金属含量的快速检测

印染 2018年第19期44卷 48-51页

作者：胡勇杰韩健健广东产品质量监督检验研究院广东广州510663

为提高浆料涂层印花儿童纺织品中重金属含量的检测效率,降低检测成本和解决环境污染,采用X射线光电子能谱仪对其进行检测,并将检测结果与现行标准方法的检测结果进行对比,探究该方法的检出限、精密度及加标回收率等,对其检测可行性进行... 详细信息

为提高浆料涂层印花儿童纺织品中重金属含量的检测效率,降低检测成本和解决环境污染,采用X射线光电子能谱仪对其进行检测,并将检测结果与现行标准方法的检测结果进行对比,探究该方法的检出限、精密度及加标回收率等,对其检测可行性进行分析。结果显示,两种方法的测定结果具有良好的相符性,检出限低至3 mg/kg,精密度小于3%,加标回收率分布在95%～104%范围内,符合浆料涂层印花儿童纺织品中重金属定量检测要求。X射线光电子能谱仪用于浆料涂层印花儿童纺织品中重金属含量的测定,具有高效快速、绿色环保检测的优点。

关键词：测试重金属含量儿童纺织品浆料涂层印花