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Zeeman and hyperfine interactions of a single Er3+167 ion in Si

Physical Review B 2022年第23期105卷 235306-235306页

作者： Jiliang Yang Wenda Fan Yangbo Zhang Changkui Duan Gabriele G. de Boo Rose L. Ahlefeldt Jevon J. Longdell Brett C. Johnson Jeffrey C. McCallum Matthew J. Sellars Sven Rogge Chunming Yin Jiangfeng Du CAS Key Laboratory of Microscale Magnetic Resonance and School of Physical Sciences University of Science and Technology of China Hefei 230026 China CAS Center for Excellence in Quantum Information and Quantum Physics University of Science and Technology of China Hefei 230026 China Centre of Excellence for Quantum Computation and Communication Technology School of Physics University of New South Wales NSW 2052 Australia Centre of Excellence for Quantum Computation and Communication Technology Research School of Physics Australian National University ACT 0200 Australia The Dodd-Walls Centre for Photonic and Quantum Technologies Department of Physics University of Otago Dunedin 9016 New Zealand Centre of Excellence for Quantum Computation and Communication Technology School of Engineering RMIT University Victoria 3001 Australia Centre of Excellence for Quantum Computation and Communication Technology School of Physics University of Melbourne Victoria 3010 Australia Hefei National Laboratory Hefei 230088 China

Er-doped Si is a promising candidate for quantum information applications due to its telecom wavelength optical transition and its compatibility with Si nanofabrication technologies. Recent spectroscopic studies based on photoluminescence excitation have shown multiple well-defined lattice sites that Er occupies in Si. Here we report a measurement of the Zeeman and hyperfine tensors of a single Er3+167 ion in Si. All the obtained tensors are highly anisotropic with the largest value principal axes aligning in nearly the same direction, and the trace of the lowest crystal field level g-tensor is 17.78±0.40. The results indicate that this specific Er site is likely to be a distorted cubic site that exhibits monoclinic (C1) symmetry. Finally, zero first-order-Zeeman fields are identified for this site and could be used to reduce decoherence of hyperfine spin states in future experiments.

关键词： Fine & hyperfine structure Zeeman effect Rare-earth doped crystals Single-electron transistors Optical spectroscopy

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Triplet Acceptors with a D-A Structure and Twisted Conformation for Efficient Organic Solar Cells

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Angewandte Chemie 2020年第35期132卷 15153-15159页

作者： Qin L. Liu X. Zhang X. Yu J. Yang L. Zhao F. Huang M. Wang K. Wu X. Li Y. Chen H. Xia J. Lu X. Gao F. Yi Y. Huang H. Center of Materials Science and Optoelectronics Engineering College of Materials Science and Opto-Electronic Technology & CAS Center for Excellence in Topological Quantum Computation & CAS Key Laboratory of Vacuum Physics University of Chinese Academy of Sciences Beijing 100049 China Department of Physics Chemistry and Biology (IFM) Linköping University Linköping 58183 Sweden Key Laboratory of Luminescence and Optical Information Ministry of Education School of Science Beijing Jiaotong University Beijing 100044 China Beijing National Laboratory for Molecular Sciences CAS Key Laboratory of Organic Solids CAS Research/Education Center for Excellence in Molecular Sciences Institute of Chemistry Chinese Academy of Sciences Beijing 100190 China State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Center of Smart Materials and Devices School of Chemistry Chemical Engineering and Life Science Wuhan University of Technology Wuhan 430070 China Department of Physics The Chinese University of Hong Kong New Territories Hong Kong

Triplet acceptors have been developed to construct high-performance organic solar cells (OSCs) as the long lifetime and diffusion range of triplet excitons may dissociate into free charges instead of net recombination when the energy levels of the lowest triplet state (T1) are close to those of charge-transfer states (3CT). The current triplet acceptors were designed by introducing heavy atoms to enhance the intersystem crossing, limiting their applications. Herein, two twisted acceptors without heavy atoms, analogues of Y6, constructed with large π-conjugated core and D-A structure, were confirmed to be triplet materials, leading to high-performance OSCs. The mechanism of triplet excitons were investigated to show that the twisted and D-A structures result in large spin–orbit coupling (SOC) and small energy gap between the singlet and triplet states, and thus efficient intersystem crossing. Moreover, the energy level of T1 is close to 3CT, facilitating the split of triplet exciton to free charges. © 2020 The Authors. Published by Wiley-VCH Verlag GmbH & Co. KGaA

关键词： D-A structures long lifetime excitons organic solar cells triplet acceptors twisted conformation

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Linear Gaussian quantum state smoothing: Understanding the optimal unravelings for Alice to estimate Bob's state

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Physical Review A 2021年第1期103卷 012213-012213页

作者： Kiarn T. Laverick Areeya Chantasri Howard M. Wiseman Centre for Quantum Computation and Communication Technology (Australian Research Council) Centre for Quantum Dynamics Griffith University Nathan Queensland 4111 Australia Optical and Quantum Physics Laboratory Department of Physics Faculty of Science Mahidol University Bangkok 10140 Thailand

Quantum state smoothing is a technique to construct an estimate of the quantum state at a particular time, conditioned on a measurement record from both before and after that time. The technique assumes that an observer, Alice, monitors part of the environment of a quantum system and that the remaining part of the environment, unobserved by Alice, is measured by a secondary observer, Bob, who may have a choice in how he monitors it. The effect of Bob's measurement choice on the effectiveness of Alice's smoothing has been studied in a number of recent papers. Here we expand upon the Letter which introduced linear Gaussian quantum (LGQ) state smoothing [Phys. Rev. Lett. 122, 190402 (2019)]. In the current paper we provide a more detailed derivation of the LGQ smoothing equations and address an open question about Bob's optimal measurement strategy. Specifically, we develop a simple hypothesis that allows one to approximate the optimal measurement choice for Bob given Alice's measurement choice. By “optimal choice” we mean the choice for Bob that will maximize the purity improvement of Alice's smoothed state compared to her filtered state (an estimated state based only on Alice's past measurement record). The hypothesis, that Bob should choose his measurement so that he observes the back-action on the system from Alice's measurement, seems contrary to one's intuition about quantum state smoothing. Nevertheless, we show that it works even beyond a linear Gaussian setting.

关键词： Open quantum systems Quantum measurements Quantum states of light Quantum stochastic processes

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Speedup in classical simulation of Gaussian boson sampling

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science Bulletin 2020年第10期65卷 832-841,M0004页

作者： Bujiao Wu Bin Cheng Fei Jia Jialin Zhang Man-Hong Yung Xiaoming Sun Institute of Computing Technology Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Institute for Quantum Science and Engineering Department of PhysicsSouthern University of Science and TechnologyShenzhen 518055China Shenzhen Key Laboratory of Quantum Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Central Research Institute Huawei TechnologiesShenzhen 518129China CAS Center of Excellence in Topological Quantum Computation Beijing 100190China

Gaussian boson sampling is an alternative model for demonstrating quantum computational supremacy,where squeezed states are injected into every input mode, instead of applying single photons as in the case of standard boson sampling. Here by analyzing numerically the computational costs, we establish a lower bound for achieving quantum computational supremacy for a class of Gaussian bosonsampling problems. Specifically, we propose a more efficient method for calculating the transition probabilities, leading to a significant reduction of the simulation costs. Particularly, our numerical results indicate that one can simulate up to 18 photons for Gaussian boson sampling at the output subspace on a normal laptop, 20 photons on a commercial workstation with 256 cores, and about 30 photons for supercomputers. These numbers are significantly smaller than those in standard boson sampling, suggesting that Gaussian boson sampling could be experimentally-friendly for demonstrating quantum computational supremacy.

关键词： Gaussian boson sampling Classical simulation Hafnian Probability distribution Marginal distribution Quantum optics

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Fluctuating magnetic droplets immersed in a sea of quantum spin liquid

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The Innovation 2023年第5期4卷 33-40页

作者： Zihao Zhu Binglin Pan Linpeng Nie Jiamin Ni Yanxing Yang Changsheng Chen Chengyu Jiang Yeyu Huang Erjian Cheng Yunjie Yu Jianjian Miao Adrian D.Hilier Xianhui Chen Tao Wu Yi Zhou Shiyan Li Lei Shu State Key Laboratory of Surface Phys ics and Department of PhysicsFudan UniversityShanghai 200433China CAS Key Laboratory of Stronglycoupled Quantum Matter Physics Department of PhysicsUniversity of Science and Technology of ChinaHefeiAnhui 230026China Department of Physics the University of Hong KongHong KongChina ISIS Pulsed Neutron and Muon Source STFC Rutherford Appleton LaboratoryHarwell CampusDidcotOxfordshire 0X110QXUK Collaborative Innovation Center of Advanced Micr ostructures Nanjing 210093China CAS Center for Excellence in Superconducting Electronics(CENSE) Shanghai 200050China Institute of Physics and Beijing National Laboratory for Condensed Matter Physics Chinese Academy of SciencesBeijing 100190China Songshan Lake Materials Laboratory DongguanGuangdong 523808China Kavli Institute for Theoretical Sciences and CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190China Shanghai Research Center for Quantum Sciences Shanghai 201315China

The search of quantum spin liquid(QSL),an exotic magnetic state with strongly fluctuating and highly entangled spins down to zero temperature,is a main theme in current condensed matter ***,there is no smoking gun evidence for deconfined spinons in any QSL candidate so *** disorders and competing exchange interactions may prevent the formation of an ideal QSL state on frustrated spin *** we report comprehensive and systematic measurements of the magnetic susceptibility,ultralow-temperature specific heat,muon spin relaxation(μSR),nuclear magnetic resonance(NMR),and thermal conductivity for NaYbSe2 single crystals,in which Yb3+ions with effective spin-1/2 form a perfect triangular *** these complementary techniques find no evidence of long-range magnetic order down to their respective base ***,specific heat,μSR,and NMR measurements suggest the coexistence of quasi-static and dynamic spins in *** scattering from these quasi-static spins may cause the absence of magnetic thermal ***,we propose a scenario of fluctuating ferrimagnetic droplets immersed in a sea of *** may be quite common on the way pursuing an ideal QSL,and provides a brand new platform to study how a QSL state survives impurities and coexists with other magnetically ordered states.

关键词： NMR immersed quantum

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Ultrashallow Junction Electrodes in Low-Loss Silicon Microring Resonators

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Physical Review Applied 2021年第4期15卷 044014-044014页

作者： Bin-Bin Xu Gabriele G. de Boo Brett C. Johnson Miloš Rančić Alvaro Casas Bedoya Blair Morrison Jeffrey C. McCallum Benjamin J. Eggleton Matthew J. Sellars Chunming Yin Sven Rogge Centre of Excellence for Quantum Computation and Communication Technology School of Physics University of New South Wales Sydney NSW 2052 Australia Centre of Excellence for Quantum Computation and Communication Technology School of Physics University of Melbourne Parkville Victoria 3010 Australia Centre of Excellence for Quantum Computation and Communication Technology School of Engineering RMIT University Melbourne Victoria 3001 Australia Centre of Excellence for Quantum Computation and Communication Technology Research School of Physics and Engineering Australian National University ACT Canberra 0200 Australia Institute of Photonics and Optical Science (IPOS) School of Physics The University of Sydney Camperdown NSW 2006 Australia The University of Sydney Nano Institute (Sydney Nano) The University of Sydney Camperdown NSW 2006 Australia CAS Key Laboratory of Microscale Magnetic Resonance and Department of Modern Physics University of Science and Technology of China Hefei 230026 China

Electrodes in close proximity to an active area of a device are required for sufficient electrical control. The integration of such electrodes into optical devices can be challenging since low optical losses must be retained to realize high-quality operation. Here, we demonstrate that it is possible to place a metallic shallow phosphorus doped layer in a silicon microring cavity that can function at cryogenic temperatures. We verify that the shallow doping layer affects the local refractive index while inducing minimal losses with quality factors up to 105. This demonstration opens up a pathway to the integration of an electronic device, such as a single-electron transistor, into an optical circuit on the same material platform.

关键词： Electrical conductivity Integrated optics Nanophotonics Optoelectronics Devices Junctions Semiconductor microcavities Cavity resonators

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Entangling and cloning machine with increasing robustness against decoherence as the number of qubits increases

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Physical Review A 2005年第6期72卷 064303-064303页

作者： Shi-Biao Zheng Guang-Can Guo Laboratory of Quantum Communication and Quantum Computation University of Science and Technology of China Hefei 230026 P. R. China Department of Electronic Science and Applied Physics Fuzhou University Fuzhou 350002 P. R. China‡

We propose a machine for entangling multiple qubits and implementing cloning and anti-cloning. The operation speed increases with the number of qubits without a limitation and thus the operation becomes more and more robust against decoherence with the increase of the number of qubits. This is contrary to usual entangling machines and quantum information processors whose performance would deteriorate with the increase of the number of qubits due to decoherence. We illustrate the idea in the ion trap system, however it can also be realized in other systems, opening a new perspective for building a scalable machine for entanglement generation and quantum information processing.

关键词： Cloning

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Characterization of a microsecond pulsed non-equilibrium atmospheric pressure Ar plasma using laser scattering and optical emission spectroscopy

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Plasma science and technology 2020年第6期22卷 120-127页

作者： Fengdong JIA Yong WU Qi MIN Maogen SU Keigo TAKEDA Kenji ISHIKAWA Hiroki KONDO Makoto SEKINE Masaru HORI Zhiping ZHONG School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049People's Republic of China Institute of Applied Physics and Computational Mathematics Beijing 100088People's Republic of China Key Laboratory of Atomic and Molecular Physics&Functional Material of Gansu Province College of Physics and Electronic EngineeringNorthwest Normal UniversityLanzhou 730070People's Republic of China Department of Electrical and Electronic Engineering Faculty of Science and TechnologyMeijo UniversityNagoya 468-8502Japan Graduate School of Engineering Nagoya UniversityNagoya 464-8603Japan CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100190People's Republic of China

A non-equilibrium atmospheric pressure argon(Ar)plasma excited by microsecond pulse is studied experimentally by laser scattering and optical emission spectroscopy(OES),and theoretically by collisional-radiative(CR)*** specifically,the electron temperature and electron density of plasma are obtained directly by the laser Thomson scattering,the gas temperature is measured by laser Raman scattering,the optical emissions of excited Ar states of plasma are measured by *** laser scattering results show that the electron temperature is about 1 eV which is similar to that excited by 60 Hz AC power,but the gas temperature is as low as 300 K compared to about 700 K excited by 60 Hz AC *** is shown that the microsecond pulsed power supply,rather than nanosecond ones,is short enough to reduce the gas temperature of atmospheric pressure plasma to near room *** electron temperature and electron density are also obtained by CR model based on OES,and find that the intensities of the optical emission intensity lines of 727.41,811.73,841.08,842.83,852.44 and 912.86 nm of Ar can be used to characterize the behavior of electron density and electron temperature,it is very useful to quickly estimate the activity of the atmospheric pressure Ar plasma in many applications.

关键词： plasma diagnosis laser Thomson scattering atmospheric pressure plasma

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Completely positive trace-preserving maps for higher-order unraveling of Lindblad master equations

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Physical Review A 2024年第6期110卷 062207-062207页

作者： Nattaphong Wonglakhon Howard M. Wiseman Areeya Chantasri Centre for Quantum Computation and Communication Technology (Australian Research Council) Centre for Quantum Dynamics Griffith University Yuggera Country Brisbane Queensland 4111 Australia Optical and Quantum Physics Laboratory Department of Physics Faculty of Science Mahidol University Bangkok 10400 Thailand

Theoretical tools used in processing continuous measurement records from real experiments to obtain quantum trajectories can easily lead to numerical errors due to a noninfinitesimal time resolution. In this work we propose a systematic assessment of the accuracy of a map. We perform error analyses for diffusive quantum trajectories, based on single-time-step Kraus operators proposed in the literature, and find the orders in time increments Δt, to which such operators satisfy the conditions for valid average quantum evolution (completely positive, convex linear, and trace preserving), and the orders to which they match the Lindblad solutions. Given these error analyses, we propose a Kraus operator that satisfies the valid average quantum evolution conditions and agrees with the Lindblad master equation, to second order in Δt, thus surpassing all other existing approaches. In order to test how well our proposed operator reproduces exact quantum trajectories, we analyze two examples of qubit measurement, where exact maps can be derived: a qubit subjected to a dispersive (z-basis) measurement and a fluorescence (dissipative) measurement. We show analytically that our proposed operator gives the smallest average trace distance to the exact quantum trajectories compared to existing approaches.

关键词： Qubits

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Strong decays of the isovector-scalar D*D¯* hadronic molecule

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Physical Review D 2024年第5期110卷 054014页

作者： Jin-Cheng Deng Bo Wang College of Physics Science and Technology Hebei Key Laboratory of High-precision Computation and Application of Quantum Field Theory Baoding 071002 China Hebei Research Center of the Basic Discipline for Computational Physics Baoding 071002 China

We adopt the effective Lagrangian approach to study the strong decays of the 1−(0++)D*D¯* molecular state [denoted as Tψ0a(4010) according to the LHCb naming convention] through triangle diagrams. The decay channels include the open-charm DD¯, and the hidden-charm ηcπ, J/ψρ, and χc1π. The coupling between the Tψ0a(4010) and its constituents D*D¯* is obtained by solving for the residue of the scattering T-matrix at the pole. Our calculations yield a total width of few tens MeV for the Tψ0a(4010) state using three different form factors, with its main decay channels being ηcπ and χc1π. The X(4100) and X(4050) have similar masses and widths, with both masses being close to the D*D¯* threshold. Additionally, their decay final states are consistent with those of the Tψ0a(4010). Therefore, it is likely that they represent the same state and both potentially correspond to the Tψ0a(4010). We suggest that future experiments focus on searching for the Tψ0a(4010) signal in the final states ηcπ−, χc1π−, and D0D− of the B0→ηcπ−K+, χc1π−K+, and D0D−K+ processes, respectively, as well as further investigating its resonance parameters with Flatté-like formula.

关键词： Hadron-hadron interactions Hadronic decays Multiquark bound states

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