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Single-photon-level quantum memory for photonic states encoded in orbital angular momentum space

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National Science Review 2014年第4期1卷 481-483页

作者： Bao-Sen Shi guang-can guo Key Laboratory of Quantum Information University of Science and Technology of China

Quantum memory is a key component of quantum networks.A successful development in enabling the distribution of quantum information requires the storage of single-photon *** quantum information is encoded using a 2D sp... 详细信息

关键词： OAM Single-photon-level quantum memory for photonic states encoded in orbital angular momentum space

Semiconductor quantum computation

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National Science Review 2019年第1期6卷 32-54页

作者： Xin Zhang Hai-Ou Li Gang Cao Ming Xiao guang-can guo guo-Ping guo Key Laboratory of Quantum Information CAS University of Science and Technology of China Synergetic Innovation Center of Quantum Information & Quantum Physics University of Science and Technology of China

Semiconductors, a significant type of material in the information era, are becoming more and more powerful in the field of quantum information. In recent decades, semiconductor quantum computation was investigated thoroughly across the world and developed with a dramatically fast speed. The research varied from initialization, control and readout of qubits, to the architecture of fault-tolerant quantum ***, we first introduce the basic ideas for quantum computing, and then discuss the developments of single-and two-qubit gate control in semiconductors. Up to now, the qubit initialization, control and readout can be realized with relatively high fidelity and a programmable two-qubit quantum processor has even been demonstrated. However, to further improve the qubit quality and scale it up, there are still some challenges to resolve such as the improvement of the readout method, material development and scalable designs. We discuss these issues and introduce the forefronts of progress. Finally, considering the positive trend of the research on semiconductor quantum devices and recent theoretical work on the applications of quantum computation, we anticipate that semiconductor quantum computation may develop fast and will have a huge impact on our lives in the near future.

关键词： semiconductor quantum dot qubit quantum computation spin manipulation

64-qubit quantum circuit simulation

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Science Bulletin 2018年第15期63卷 964-971页

作者： Zhao-Yun Chen Qi Zhou Cheng Xue Xia Yang guang-can guo guo-Ping guo CAS Key Laboratory of Quantum information University of Science and Technology of China Hefei 230026 China Origin Quantum Computing Company Limited Hefei 230026 China

Classical simulations of quantum circuits are limited in both space and time when the qubit count is above 50, the realm where quantum supremacy reigns. However, recently, for the low depth circuit with more than 50 qubits, there are several methods of simulation proposed by teams at Google and IBM. Here,we present a scheme of simulation which can extract a large amount of measurement outcomes within a short time, achieving a 64-qubit simulation of a universal random circuit of depth 22 using a 128-node cluster, and 56-and 42-qubit circuits on a single PC. We also estimate that a 72-qubit circuit of depth 23 can be simulated in about 16 h on a supercomputer identical to that used by the IBM team. Moreover, the simulation processes are exceedingly separable, hence parallelizable, involving just a few inter-process communications. Our work enables simulating more qubits with less hardware burden and provides a new perspective for classical simulations.

关键词： Simulation of quantum circuits Universal random circuit Quantum supremacy Partitioning Parallel computing

Non-Markovian discrete qubit dynamics

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Science Bulletin 2016年第13期61卷 1031-1036页

作者： Jun Sun Yong-Nan Sun Chuan-Feng Li guang-can guo Kimmo Luoma Jyrki Piilo Key Laboratory of Quantum Information University of Scienceand Technology of China Chinese Academy of SciencesHefei 230026 China Synergetic Innovation Center of Quantum Information andQuantum Physics University of Science and Technology of China Hefei 230026 China Institut fur Theoretische Physik Technische Universitat Dresden 01062 Dresden Germany Department of Physics and Astronomy Turku Centre for Quantum Physics University of Turku20014 Turun Yliopisto Finland

The study of open quantum systems is important for fundamental issues of quantum physics as well as for technological applications such as quantum information processing. The interaction of a quantum system with its environment is usually detrimental for the quantum properties of the system and leads to decoherence. However,sometimes a quantum control can lead to a coherent partial exchange of information between the system and the dynamics of the open system might become non-Markovian. In this article, we study experimentally discrete nonMarkovian open quantum system dynamics. We implement a local control protocol using linear optics for controlling the information flow between the open system and the environment. We show how the transition from Markovian to non-Markovian dynamics can be controlled using only local operations for the open system.

关键词： Non-Markovian dynamics Openquantum system Quantum optics Coherent opticaleffects

Measurement of Spin Singlet-Triplet Qubit in Quantum Dots Using Superconducting Resonator

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Chinese Physics Letters 2020年第2期37卷 6-10页

作者： Xing-Yu Zhu Tao Tu Ao-Lin guo Zong-Quan Zhou guang-can guo Key Laboratory of Quantum Information University of Science and Technology of ChinaChinese Academy of SciencesHefei 230026

The spin qubit in quantum dots is one of the leading platforms for quantum computation.A crucial requirement for scalable quantum information processing is the high efficient *** we analyze the measurement process of a quantum-dot spin qubit coupled to a superconducting transmission line ***,the phase shift of the resonator is sensitive to the spin states and the gate *** response of the resonator can be used to measure the spin qubit efficiently,which can be extend to read out the multiple spin qubits in a scalable solid-state quantum processor.

关键词： computation. quantum measurement.

Experimental demonstration of switching entangled photons based on the Rydberg blockade effect

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Science China(Physics,Mechanics & Astronomy) 2020年第11期63卷 20-26页

作者： Yi-Chen Yu Ming-Xin Dong Ying-Hao Ye guang-can guo Dong-Sheng Ding Bao-Sen Shi Key Laboratory of Quantum Information University of Science andTechnology of ChinaHefei 230026China Synergetic Innovation Center of Quantum Information and Quantum Physics University of Science and Technology of ChinaHefei 230026China

The long-range interaction between Rydberg-excited atoms endows a medium with large optical ***,we demonstrate an optical switch to operate on a single photon from an entangled photon pair under a Rydberg electromagnetically induced transparency *** the presence of the Rydberg blockade effect,we switch on a gate field to make the atomic medium nontransparent thereby absorbing the single photon emitted from another atomic ensemble via the spontaneous fourwave mixing *** contrast to the case without a gate field,more than 50%of the photons sent to the switch are blocked,and finally achieve an effective single-photon *** are on average 1-2 gate photons per effective blockade sphere in one gate *** switching effect on a single entangled photon depends on the principal quantum number and the photon number of the gate *** experimental progress is significant in the quantum information process especially in controlling the interaction between Rydberg atoms and entangled photon pairs.

关键词： Rydberg blockade entangled photon quantum switch

Angular-spectrum-dependent interference

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Light(Science & Applications) 2021年第11期10卷 2226-2232页

作者： Chen Yang Zhi-Yuan Zhou Yan Li Shi-Kai Liu Zheng Ge guang-can guo Bao-Sen Shi CAS Key Laboratory of Quantum Information University of Science and Technology of ChinaHefeiAnhuiChina Synergetic Innovation Center of Quantum Information&Quantum Physics University of Science and Technology of ChinaHefeiAnhuiChina

Optical interference is not only a fundamental phenomenon that has enabled new theories of light to be derived but it has also been used in interferometry for the measurement of small displacements,refractive index changes,and surface *** a two-beam interferometer,variations in the interference fringes are used as a diagnostic for anything that causes the optical path difference(OPD)to change;therefore,for a specified OPD,greater variation in the fringes indicates better measurement ***,we introduce and experimentally validate an interesting optical interference phenomenon that uses photons with a structured frequency-angular spectrum,which are generated from a spontaneous parametric down-conversion process in a nonlinear *** interference phenomenon is manifested as interference fringes that vary much more rapidly with increasing OPD than the corresponding fringes for equal-inclination interference;the phenomenon is parameterised using an equivalent wavelength,which under our experimental conditions is 29.38 nm or about 1/27 of the real *** phenomenon not only enriches the knowledge with regard to optical interference but also offers promise for applications in interferometry.

关键词： interferometer spectrum interferometry

A universal simulating framework for quantum key distribution systems

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Science China(Information Sciences) 2020年第8期63卷 122-136页

作者： Guan-Jie FAN-YUAN Wei CHEN Feng-Yu LU Zhen-Qiang YIN Shuang WANG guang-can guo Zheng-Fu HAN CAS Key Laboratory of Quantum Information University of Science and Technology of China State Key Laboratory of Cryptography

Quantum key distribution(QKD) provides a physical-based way to conciliate keys between remote users securely. Simulation is an essential method for designing and optimizing QKD systems. We develop a universal simulation framework based on quantum operator descriptions of photon signals and optical devices. The optical devices can be freely combined and driven by the photon excitation events,which make it appropriate for arbitrary QKD systems in principle. Our framework focuses on realistic characters of optical devices and system structures. The imperfections of the devices and the non-local properties of a quantum system are taken into account when modeling. We simulate the single-photon and Hong-Ou-Mandel(HOM) interference optical units, which are fundamental of QKD systems. The results using this event-driven framework agree well with the theoretical results, which indicate its feasibility for QKD.

关键词： quantum key distribution quantum optics simulation modeling C++

Simultaneous observation of quantum contextuality and quantum nonlocality

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Science Bulletin 2018年第17期63卷 1092-1095页

作者： Xiao-Min Hu Bi-Heng Liu Jiang-Shan Chen Yu guo Yu-Chun Wu Yun-Feng Huang Chuan-Feng Li guang-can guo CAS Key Laboratory of Quantum Information University of science and Technology of China Hefei 230026 China

Quantum nonlocality and quantum contextuality are the most curious properties that change our understanding of nature, and were observed independently in recent decades. One important question is whether both properties can be observed simultaneously. In this paper, we show that in a qutrit-qutrit system we can observe quantum nonlocality and quantum contextuality at the same time. From the perspective of quantum information, our experiment proves in principle that the two resources, quantum nonlocality and quantum contextuality, can be utilized simultaneously.

关键词： Quantum contextuality Quantum nonlocality Monogamy Qutrit-qutrit system