检索结果-内蒙古大学图书馆

arXiv 2020年

作者： Fujisawa, Y. Pardo-Almanza, M. Garland, J. Yamagami, K. Zhu, X. Chen, X. Araki, K. Takeda, T. Kobayashi, M. Takeda, Y. Hsu, C.H. Chuang, F.C. Laskowski, R. Khoo, K.H. Soumyanarayanan, A. Okada, Yoshinori Okinawa904-0495 Japan Applied Physics & Mathematics Department Northeastern University BostonMA02115 United States Institute of Materials Research and Engineering Agency for Science Technology and Research Singapore138634 Singapore Department of Electrical Engineering and Information Systems University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-8656 Japan Center for Spintronics Research Network University of Tokyo 7-3-1 Hongo Bunkyo-ku Tokyo113-8656 Japan Condensed Matter Science Division Quantum Beam Science Directorate Japan Atomic Energy Agency 1-1-1 Kouto Sayo-cho Sayo-gunHyogo679-5148 Japan Department of Physics National Sun Yat-sen University Kaohsiung80424 Taiwan Institute of High Performance Computing Agency for Science Technology and Research 138632 Singapore Department of Physics National University of Singapore 117551 Singapore

Magnetic transition metal dichalcogenide (TMD) films have recently emerged as promising candidates to host novel magnetic phases relevant to next-generation spintronic devices. However, systematic control of the magnetization orientation, or anisotropy, and its thermal stability, characterized by Curie temperature (Tc) – remains to be achieved in such films. Here we present self-intercalated epitaxial Cr1+δTe2 films as a platform for achieving systematic/smooth magnetic tailoring in TMD films. Using a molecular beam epitaxy (MBE) based technique, we have realized epitaxial Cr1+δTe2 films with smoothly tunable δ over a wide range (0.33-0.82), while maintaining NiAs-type crystal structure. With increasing δ, we found monotonic enhancement of Tc from 160 to 350 K, and the rotation of magnetic anisotropy from out-of-plane to in-plane easy axis configuration for fixed film thickness. Contributions from conventional dipolar and orbital moment terms are insufficient to explain the observed evolution of magnetic behavior with δ. Instead, ab initio calculations suggest that the emergence of antiferromagnetic interactions with δ, and its interplay with conventional ferromagnetism, may play a key role in the observed trends. To our knowledge, this constitutes the first demonstration of tunable Tc and magnetic anisotropy across room temperature in TMD films, and paves the way for engineering novel magnetic phases for spintronic applications. Copyright © 2020, The Authors. All rights reserved.

关键词： Transition metals

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Joint Determination of Reactor Antineutrino Spectra from 235U and 239Pu Fission by Daya Bay and PROSPECT

arXiv

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arXiv 2021年

作者： An, F.P. Andriamirado, M. Balantekin, A.B. Band, H.R. Bass, C.D. Bergeron, D.E. Berish, D. Bishai, M. Blyth, S. Bowden, N.S. Bryan, C.D. Cao, G.F. Cao, J. Chang, J.F. Chang, Y. Chen, H.S. Chen, S.M. Chen, Y. Chen, Y.X. Cheng, J. Cheng, Z.K. Cherwinka, J.J. Chu, M.C. Classen, T. Conant, A.J. Cummings, J.P. Dalager, O. Deichert, G. Delgado, A. Deng, F.S. Ding, Y.Y. Diwan, M.V. Dohnal, T. Dolinski, M.J. Dolzhikov, D. Dove, J. Dvořák, M. Dwyer, D.A. Erickson, A. Foust, B.T. Gaison, J.K. Galindo-Uribarri, A. Gallo, J.P. Gilbert, C.E. Gonchar, M. Gong, G.H. Gong, H. Grassi, M. Gu, W.Q. Guo, J.Y. Guo, L. Guo, X.H. Guo, Y.H. Guo, Z. Hackenburg, R.W. Hans, S. Hansell, A.B. He, M. Heeger, K.M. Heffron, B. Heng, Y.K. Hor, Y.K. Hsiung, Y.B. Hu, B.Z. Hu, Jianrun R. Hu, T. Hu, Z.J. Huang, H.X. Huang, J.H. Huang, X.T. Huang, Y.B. Huber, P. Koblanski, J. Jaffe, D.E. Jayakumar, S. Jen, K.L. Ji, X.L. Ji, X.P. Johnson, R.A. Jones, D.C. Kang, L. Kettell, S.H. Kohn, S. Kramer, M. Kyzylova, O. Lane, C.E. Langford, T.J. LaRosa, J. Lee, J.H.C. Lei, R.T. Leitner, R. Leung, J.K.C. Li, F. Li, H.L. Li, J.J. Li, Q.J. Li, R.H. Li, S. Li, S.C. Li, W.D. Li, X.N. Li, X.Q. Li, Y.F. Li, Z.B. Liang, H. Lin, C.J. Lin, G.L. Lin, S. Ling, J.J. Link, J.M. Littenberg, L. Littlejohn, B.R. Liu, J.C. Liu, J.L. Liu, J.X. Lu, C. Lu, H.Q. Lu, X. Luk, K.B. Ma, B.Z. Ma, X.B. Ma, X.Y. Ma, Y.Q. Mandujano, R.C. Maricic, J. Marshall, C. McDonald, K.T. McKeown, R.D. Mendenhall, M.P. Meng, Y. Meyer, A.M. Milincic, R. Mueller, P.E. Mumm, H.P. Napolitano, J. Naumov, D. Naumova, E. Neilson, R. Nguyen, T.M.T. Nikkel, J.A. Nour, S. Ochoa-Ricoux, J.P. Olshevskiy, A. Palomino, J.L. Pan, H.-R. Park, J. Patton, S. Peng, J.C. Pun, C.S.J. Pushin, D.A. Qi, F.Z. Qi, M. Qian, X. Raper, N. Ren, J. Morales Reveco, C. Rosero, R. Roskovec, B. Ruan, X.C. Searles, M. Steiner, H. Sun, J.L. Surukuchi, P.T. Tmej, T. Treskov, K. Institute of Modern Physics East China University of Science and Technology Shanghai China Department of Physics Illinois Institute of Technology ChicagoIL United States Department of Physics University of Wisconsin Madison MadisonWI United States Wright Laboratory Department of Physics Yale University New HavenCT United States Department of Physics Le Moyne College SyracuseNY United States National Institute of Standards and Technology GaithersburgMD United States Department of Physics Temple University PhiladelphiaPA United States Brookhaven National Laboratory UptonNY United States Department of Physics National Taiwan University Taipei Taiwan Nuclear and Chemical Sciences Division Lawrence Livermore National Laboratory LivermoreCA United States High Flux Isotope Reactor Oak Ridge National Laboratory Oak RidgeTN United States Institute of High Energy Physics Beijing China National United University Miao-Li Liechtenstein Department of Engineering Physics Tsinghua University Beijing China Shenzhen University Shenzhen China University Guangzhou China North China Electric Power University Beijing China Chinese University of Hong Kong Hong Kong Siena College LoudonvilleNY12211 United States Department of Physics and Astronomy University of California IrvineCA92697 United States Physics Division Oak Ridge National Laboratory Oak RidgeTN United States Department of Physics and Astronomy University of Tennessee KnoxvilleTN United States University of Science and Technology of China Hefei China Charles University Faculty of Mathematics and Physics Prague Czech Republic Department of Physics Drexel University PhiladelphiaPA United States Joint Institute for Nuclear Research Moscow Region Dubna Russia Department of Physics University of Illinois at Urbana-Champaign UrbanaIL61801 United States Lawrence Berkeley National Laboratory BerkeleyCA94720 United States George W. Woodruff School of Mechanical Engineering Georgia Institute

A joint determination of the reactor antineutrino spectra resulting from the fission of 235U and 239Pu has been carried out by the Daya Bay and PROSPECT collaborations. This Letter reports the level of consistency of 235U spectrum measurements from the two experiments and presents new results from a joint analysis of both data sets. The measurements are found to be consistent. The combined analysis reduces the degeneracy between the dominant 235U and 239Pu isotopes and improves the uncertainty of the 235U spectral shape to about 3%. The 235U and 239Pu antineutrino energy spectra are unfolded from the jointly deconvolved reactor spectra using the Wiener-SVD unfolding method, providing a data-based reference for other reactor antineutrino experiments and other applications. This is the first measurement of the 235U and 239Pu spectra based on the combination of experiments at low- and highly enriched uranium reactors. © 2021, CC BY.

关键词： Uncertainty analysis

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Entanglement entropy, quantum fluctuations, and thermal entropy in topological phases

arXiv

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arXiv 2019年

作者： Hu, Yuting Wan, Yidun State Key Laboratory of Surface Physics Fudan University Shanghai200433 China Department of Physics Center for Field Theory and Particle Physics Fudan University Shanghai200433 China Institute for Nanoelectronic Devices and Quantum Computing Fudan University Shanghai200433 China Department of Physics Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen518055 China CAS Key Laboratory of Microscale Magnetic Resonance Department of Modern Physics University of Science and Technology of China Hefei Anhui230026 China Collaborative Innovation Center of Advanced Microstructures Nanjing210093 China

Entanglement entropy in topologically ordered matter phases has been computed extensively using various methods. In this paper, we study the entanglement entropy of topological phases in two-spaces from a new perspective-the perspective of quasiparticle fluctuations. In this picture, the entanglement spectrum of a topologically ordered system is identified with the spectrum of quasiparticle fluctuations of the system, and the entanglement entropy measures the maximal quasiparticle fluctuations on the EB. As a consequence, entanglement entropy corresponds to the thermal entropy of the quasiparticles at infinite temperature on the entanglement boundary. We corroborates our results with explicit computation in the quantum double model with/without boundaries. We then systematically construct the reduced density matrices of the quantum double model on generic 2-surfaces with boundaries. Copyright © 2019, The Authors. All rights reserved.

关键词： Entropy

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Efficient Verification of Pure quantum States in the Adversarial Scenario

arXiv

引用

arXiv 2019年

作者： Zhu, Huangjun Hayashi, Masahito Department of Physics Center for Field Theory and Particle Physics Fudan University Shanghai200433 China State Key Laboratory of Surface Physics Fudan University Shanghai200433 China Institute for Nanoelectronic Devices and Quantum Computing Fudan University Shanghai200433 China Collaborative Innovation Center of Advanced Microstructures Nanjing210093 China Graduate School of Mathematics Nagoya University Nagoya464-8602 Japan Shenzhen Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen518055 China Centre for Quantum Technologies National University of Singapore 3 Science Drive 2 117542 Singapore

Efficient verification of pure quantum states in the adversarial scenario is crucial to many applications in quantum information processing, such as blind measurement-based quantum computation and quantum networks. However, little is known about this subject so far. Here we establish a general framework for verifying pure quantum states in the adversarial scenario and clarify the resource cost. Moreover, we propose a simple and general recipe to constructing efficient verification protocols for the adversarial scenario from protocols for the nonadversarial scenario. With this recipe, arbitrary pure states can be verified in the adversarial scenario with almost the same efficiency as in the nonadversarial scenario. Many important quantum states in quantum information processing can be verified in the adversarial scenario with unprecedented high efficiencies. Copyright © 2019, The Authors. All rights reserved.

关键词： quantum optics

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General framework for verifying pure quantum states in the adversarial scenario

arXiv

引用

arXiv 2019年

Bipartite and multipartite entangled states are of central interest in quantum information processing and foundational studies. Efficient verification of these states, especially in the adversarial scenario, is a key to various applications, including quantum computation, quantum simulation, and quantum networks. However, little is know about this topic in the adversarial scenario. Here we initiate a systematic study of pure-state verification in the adversarial scenario. In particular, we introduce a general method for determining the minimal number of tests required by a given strategy to achieve a given precision. In the case of homogeneous strategies, we can even derive an analytical formula. Furthermore, we propose a general recipe to verifying pure quantum states in the adversarial scenario by virtue of protocols for the nonadversarial scenario. Thanks to this recipe, the resource cost for verifying an arbitrary pure state in the adversarial scenario is comparable to the counterpart for the nonadversarial scenario, and the overhead is at most three times for high-precision verification. Our recipe can readily be applied to efficiently verify bipartite pure states, stabilizer states, hypergraph states, weighted graph states, and Dicke states in the adversarial scenario. This paper is an extended version of the companion paper [1]. Copyright © 2019, The Authors. All rights reserved.

关键词： quantum chemistry

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Optimal verification and fidelity estimation of maximally entangled states

arXiv

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arXiv 2019年

We study the verification of maximally entangled states by virtue of the simplest measurement settings: local projective measurements without adaption. We show that optimal protocols are in one-to-one correspondence with complex projective 2-designs constructed from orthonormal bases. Optimal protocols with minimal measurement settings are in one-to-one correspondence with complete sets of mutually unbiased bases. Based on this observation, optimal protocols are constructed explicitly for any local dimension, which can also be applied to estimating the fidelity with the target state and to detecting entanglement. In addition, we show that incomplete sets of mutually unbiased bases are optimal for verifying maximally entangled states when the number of measurement settings is restricted. Moreover, we construct optimal protocols for the adversarial scenario in which state preparation is not trusted. The number of tests has the same scaling behavior as the counterpart for the nonadversarial scenario;the overhead is no more than three times. We also show that the entanglement of the maximally entangled state can be certified with any given significance level using only one test as long as the local dimension is large enough. Copyright © 2019, The Authors. All rights reserved.

关键词： quantum entanglement

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Characterization of a Disordered above Room Temperature Skyrmion Material Co8Zn8Mn4

arXiv

引用

arXiv 2020年

作者： Henderson, Melissa E. Beare, J. Sharma, S. Bleuel, M. Clancy, P. Cory, D.G. Huber, M.G. Marjerrison, C.A. Pula, M. Sarenac, D. Smith, E.M. Zhernenkov, K. Luke, G.M. Pushin, D.A. Institute for Quantum Computing University of Waterloo WaterlooONN2L3G1 Canada Department of Physics & Astronomy University of Waterloo WaterlooONN2L3G1 Canada Department of Physics and Astronomy McMaster University HamiltonONL8S 4M1 Canada National Institute of Standards and Technology GaithersburgMD20899 United States Department of Materials Science and Engineering University of Maryland College ParkMD20742-2115 United States Brockhouse Institute for Materials Research HamiltonONL8S 4M1 Canada Department of Chemistry University of Waterloo WaterlooONN2L3G1 Canada National Institute of Standards and Technology GaithersburgMD20899 United States Jülich Centre for Neutron Science Heinz Maier-Leibnitz Zentrum Forschungszentrum Jülich GmbH Garching85748 Germany

Topologically non trivial spin textures host great promise for future spintronic applications. Skyrmions in particular are of burgeoning interest owing to their nanometric size, topological protection, and high mobility via ultra-low current densities. It has been previously reported through magnetic susceptibility, microscopy, and scattering techniques that Co8Zn8Mn4 forms an above room temperature triangular skyrmion lattice. Here we report the synthesis procedure and characterization of a polycrystalline Co8Zn8Mn4 bulk sample. We employ powder x-ray diffraction, backscatter Laue diffraction, and neutron diffraction as characterization tools of the crystallinity of the samples, while magnetic susceptibility and Small Angle Neutron Scattering (SANS) measurements are performed to study the skyrmion phase. Magnetic susceptibility measurements show a dip anomaly in the magnetization curves which persists over a range of approximately 305 K- 315 K. SANS measurements reveal a rotationally disordered polydomain skymrion lattice. Applying a recently developed symmetry-breaking magnetic field sequence, we were able to orient and order the previously jammed state to yield the prototypical hexagonal diffraction patterns, with secondary diffraction rings. Copyright © 2020, The Authors. All rights reserved.

关键词： Manganese alloys

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Upper bounds for relative entropy of entanglement based on convex hull approximation

arXiv

引用

arXiv 2019年

作者： Hou, Shi-Yao Cao, Chenfeng Zhou, D.L. Zeng, Bei College of Physics and Electronic Engineering Center for Computational Sciences Sichuan Normal University Chengdu610068 China Center for Quantum Computing Peng Cheng Laboratory Shenzhen518055 China Department of Physics Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong China Institute of Physics Beijing National Laboratory for Condensed Matter Physics Chinese Academy of Sciences Beijing100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing100049 China CAS Central of Excellence in Topological Quantum Computation Beijing100190 China Songshan Lake Materials Laboratory Dongguan Guangdong523808 China Department of Mathematics & Statistics University of Guelph GuelphON Canada Institute for Quantum Computing University of Waterloo WaterlooON Canada

Quantifying entanglement for multipartite quantum state is a crucial task in many aspects of quantum information theory. Among all the entanglement measures, relative entropy of entanglement ERis an important quantity due to its clear geometric meaning, easy compatibility with different system sizes, and various applications in many other related quantity calculations. Lower bounds of ERwere previously found based on distance to the set of positive partial transpose states. We propose a method to calculate upper bounds of ERbased on the convex hull approximation of the set of separable states. We apply our method to calculate ERfor composite systems of various sizes, and compare with the previous known lower bounds, obtaining promising results. Our method adds a new tool for entanglement measure calculation and deepens our understanding for the structure of separable states. Copyright © 2019, The Authors. All rights reserved.

关键词： Computational geometry

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Observation of three-photon spontaneous parametric downconversion in a superconducting parametric cavity

arXiv

引用

arXiv 2019年

作者： Sandbo Chang, C.W. Sabín, Carlos Forn-Díaz, P. Quijandría, Fernando Vadiraj, A.M. Nsanzineza, I. Johansson, G. Wilson, C.M. Institute for Quantum Computing and Electrical and Computer Engineering University of Waterloo Waterloo Canada Instituto de Física Fundamental CSIC Serrano 113-bis Madrid28006 Spain 08193 Spain Barcelona Supercomputing Center - CNS Barcelona08034 Spain Microtechnology and Nanoscience MC2 Chalmers University of Technology GöteborgSE-412 96 Sweden

Spontaneous parametric downconversion (SPDC) has been a key enabling technology in exploring quantum phenomena and their applications for decades. For instance, traditional SPDC, which splits a high energy pump photon into two lower energy photons, is a common way to produce entangled photon pairs. Since the early realizations of SPDC, researchers have thought to generalize it to higher order, e.g., to produce entangled photon triplets. However, directly generating photon triplets through a single SPDC process has remained elusive. Here, using a flux-pumped superconducting parametric cavity, we demonstrate direct three-photon SPDC, with photon triplets generated in a single cavity mode or split between multiple modes. With strong pumping, the states can be quite bright, with flux densities exceeding 60 photon/s/Hz. The observed states are strongly non-Gaussian, which has important implications for potential applications. In the single-mode case, we observe a triangular star-shaped distribution of quadrature voltages, indicative of the long-predicted "star state". The observed star state shows strong third-order correlations, as expected for a state generated by a cubic Hamiltonian. By pumping at the sum frequency of multiple modes, we observe strong three-body correlations between multiple modes, strikingly, in the absence of second-order correlations. We further analyze the third-order correlations under mode transformations by the symplectic symmetry group, showing that the observed transformation properties serve to "fingerprint" the specific cubic Hamiltonian that generates them. The observed non-Gaussian, third-order correlations represent an important step forward in quantum optics and may have a strong impact on quantum communication with microwave fields as well as continuous-variable quantum computation. Copyright © 2019, The Authors. All rights reserved.

关键词： Photons

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Laser damage attack against optical attenuators in quantum key distribution

arXiv

引用

arXiv 2019年

作者： Huang, Anqi Li, Ruoping Egorov, Vladimir Tchouragoulov, Serguei Kumar, Krtin Makarov, Vadim Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology Changsha410073 China Greatwall Quantum Laboratory China Greatwall Technology Changsha410205 China Institute for Quantum Computing University of Waterloo WaterlooONN2L 3G1 Canada Department of Electrical and Computer Engineering University of Waterloo WaterlooONN2L 3G1 Canada Department of Physics and Astronomy University of Waterloo WaterlooONN2L 3G1 Canada Faculty of Photonics and Optical Information ITMO University 199034 Kadetskaya line 3b St. Petersburg Russia QGLex Incorporated 105 Schneider Road Suite 111 OttawaONK2K 1Y3 Canada Russian Quantum Center Skolkovo Moscow143025 Russia Shanghai Branch National Laboratory for Physical Sciences at Microscale and CAS Center for Excellence in Quantum Information University of Science and Technology of China Shanghai201315 China NTI Center for Quantum Communications National University of Science and Technology MISiS Moscow119049 Russia

Many quantum key distribution systems employ a laser followed by an optical attenuator to prepare weak coherent states in the source. Their mean photon number must be pre-calibrated to guarantee the security of key distribution. Here we experimentally show that this calibration can be broken with a high-power laser attack. We have tested four fiber-optic attenuator types used in quantum key distribution systems, and found that two of them exhibit a permanent decrease in attenuation after laser damage. This results in higher mean photon numbers in the prepared states and may allow an eavesdropper to compromise the key. Copyright © 2019, The Authors. All rights reserved.

关键词： Photons

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