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Antiferromagnetically ordered mott insulator and d+id superconductivity in twisted bilayer graphene: a quantum Monte Carlo study

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Science Bulletin 2019年第5期64卷 310-314页

作者： Tongyun Huang Lufeng Zhang Tianxing Ma Department of Physics Beijing Normal University

Using exact quantum Monte Carlo method, we examine the recent novel electronic states seen in magicangle graphene superlattices. From the Hubbard model on a double-layer honeycomb lattice with a rotation angle θ=1:08°, we reveal that an antiferromagnetically ordered mott insulator emerges beyond a critical U_c at half filling, and with a small doping, the pairing with d+id symmetry dominates over other pairings at low temperature. The effective d+id pairing interaction strongly increases as the on-site Coulomb interaction increases, indicating that the superconductivity is driven by electron-electron correlation. Our non-biased numerical results demonstrate that the twisted bilayer graphene shares the similar superconducting mechanism of high temperature superconductors, which is a new and ideal platform for further investigating the strongly correlated phenomena.

关键词： Twisted bilayer graphene mott insulator Superconductivity Quantum Monte Carlo

Fragmentation model for large L/D (Length over Diameter) explosive fragmentation warheads

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Defence Technology（防务技术） 2017年第4期13卷 300-309页

作者： Vladimir M. Gold US Army RDECOM-ARDEC Attn: RDAR-MEE-F Picatinny Arsenal NJ 07806-5000 USA

New advanced numerical computer model enabling accurate simulation of fragmentation parameters of large Length over Diameter(L/D)explosively driven metal shells has been developed and validated.The newly developed large L/D multi-region model links three-dimensional axisymmetric high strain high strain-rate hydrocode analyses with the conventional set of Picatinny Arsenal FRAGmentation(PAFRAG)simulation routines.The standard PAFRAG modeling technique is based on the mott's theory of break-up of idealized cylindrical"ring-bombs",in which the length of the average fragment is a function of the radius and velocity of the shell at the moment of break-up,and the mechanical properties of the metal.In the newly developed multi-region model,each of the shell region,the break-up is assumed to occur instantaneously,whereas the entire shell is modeled to fragment at multiple times,according to the number of the regions considered.According to PAFRAG methodology,the required input for both the natural and the controlled fragmentation models including the geometry and the velocity of the shell at moment of break-up had been provided from the hydrocode analyses and validated with available experimental data.The newly developed large L/D multi-region PAFRAG model has been shown to accurately reproduce available experimental fragmentation data.

关键词： Explosive fragmentation modeling Natural fragmentation mott model PAFRAG Fragmentation warhead lethality performance

Critical temperature and condensed fraction of Bose-Einstein condensation in optical lattices

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Science China(Physics,Mechanics & Astronomy) 2007年第2期50卷 177-184页

作者： YU XueCai HUANG Xue YE YuTang School of Opto-Electrical Information University of Electronic Science and Technology of ChinaChengdu 610054China

Critical temperature and condensate fraction of Bose-Einstein condensation in the optical lattice are studied. The results show that the critical temperature in optical lattices can be characterized with an equivalent critical temperature in a single lattice, which provide a fast evaluation of critical temperature and condensate fraction of Bose-Einstein condensation confined with pure optical trap. Critical temperature can be estimated with an equivalent critical temperature. It is predicted that critical temperature is proportional to q in q number lattices for superfluid state and should be equal to that in a single lattic for mott insulate state. Required potential depth or Rabi frequency and maximum atom number in the lattices both for superfluid state and mott state are presented based on views of thermal mechanical statistics.

关键词： Bose-Einstein condensation critical temperature optical lattice superfluid state mott insulate state

Study on mott-Insulator-Superfluid Phase Transition in Symmetric and Unsymmetric Double-Chain Bose-Hubbard Model

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Journal of Harbin Institute of Technology(New Series) 2019年第1期26卷 61-67页

作者： Rongsheng Han Zhihong Liu Liang Chen Jialu Fu Mathematics and Physics Department North China Electric Power University

The symmetric and the asymmetric double-chain Bose-Hubbard Models( BHMs) are studied by the mean-field theory. By using Landau's quantum phase transition theory,phase diagrams for systems with different hopping energies and repulsive interactions are obtained. Thereby,mott-insulator-superfluid( MISF)phase transition boundaries are determined. Our results show that tunneling effects between two chains provide additional channels for particles hopping between corresponding optical lattice sites of different chains,which makes easier for systems to transit from MI to SF phase. The two-site parity function is also utilized to investigate the properties of the system near the quantum phase transit point.We found that the increase of inter-chain hopping will reinforce the tunneling effects between two chains,and reduce the intrachain tunneling effects within the same chain.

关键词： Bose-Hubbard model mott Insulator-Superfluid Phase Transition Landau theory

超冷87Rb原子在二维光晶格中mott绝缘态的实验实现

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物理学报 2020年第19期69卷 74-80页

作者：文凯王良伟周方陈良超王鹏军孟增明张靖山西大学光电研究所量子光学与光量子器件国家重点实验室太原030006 山西大学极端光学协同创新中心太原030006

超冷原子气体的量子相变是研究量子关联多体物理的核心内容之一.本文采用单一激光光束通过折叠反射产生二维光晶格,通过控制激光偏振产生两种不同的二维光晶格结构,一种是两个独立的一维光晶格构成,另一种是两个方向的一维光晶格互相干... 详细信息

超冷原子气体的量子相变是研究量子关联多体物理的核心内容之一.本文采用单一激光光束通过折叠反射产生二维光晶格,通过控制激光偏振产生两种不同的二维光晶格结构,一种是两个独立的一维光晶格构成,另一种是两个方向的一维光晶格互相干涉形成.将超冷87Rb原子装载到二维光晶格中,通过改变光晶格激光功率调控原子在光晶格中的隧穿强度和相互作用强度,观察到87Rb原子从超流态到mott绝缘态之间的量子相变,并且分析了两种光晶格对量子相变的影响,为今后开展光晶格中强关联物理研究奠定基础.

关键词：光晶格量子相变量子关联多体物理超流 mott 绝缘态

mott transition in ruby lattice Hubbard model

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Chinese Physics B 2019年第5期28卷 256-262页

作者：保安 Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences

mott transition in a ruby lattice with fermions described by the Hubbard model including on-site repulsive interaction is investigated by combining the cellular dynamical mean-field theory and the continuous-time quantum Monte Carlo algorithm. The effect of temperature and on-site repulsive interaction on the metallic–insulating phase transition in ruby lattice with fermions is discussed based on the density of states and double occupancy. In addition, the magnetic property of each phase is discussed by defining certain magnetic order parameters. Our results show that the antiferromagnetic metal is found at the low temperature and weak interaction region and the antiferromagnetic insulating phase is found at the low temperature and strong interaction region. The paramagnetic metal appears in whole on-site repulsive interaction region when the temperature is higher than a certain value and the paramagnetic insulator appears at the middle scale of temperature and on-site repulsive interaction.

关键词： mott transition ruby lattice Hubbard model cellular dynamical mean-field theory

Critical Theory of Two-Dimensional mott Transition: Integrability and Hilbert Space Mapping

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Journal of Modern Physics 2015年第5期6卷 634-639页

作者： Federico L. Bottesi Guillermo R. Zemba Facultad de Ingeniería Pontificia Universidad Católica Argentina Buenos Aires Argentina Physics Department Comisión Nacional de Energía Atómica Buenos Aires Argentina

We reconsider the mott transition in the context of a two-dimensional fermion model with density-density coupling. We exhibit a Hilbert space mapping between the original model and the Double Lattice Chern-Simons theory at the critical point by use of the representation theory of the q-oscillator and Weyl algebras. The transition is further characterized by the ground state modification. The explicit mapping provides a new tool to further probe and test the detailed physical properties of the fermionic lattice model considered here and to enhance our understanding of the mott transition(s).

关键词： mott Transition Conformal Field Theory Chern-Simons Theory Effective Field Theory Quantum Groups Integrable Models Strongly Correlated Electrons

Russell body duodenitis in a patient with retroperitoneal metastasis of ureteral cancer

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World Journal of Gastroenterology 2013年第1期19卷 125-128页

作者： Yoshihisa Takahashi Seiichiro Shimizu Koji Uraushihara Toshio Fukusato Department of Pathology Teikyo University School of MedicineTokyo 173-8605Japan Department of Pathology Showa General HospitalTokyo 187-8510Japan Department of Gastrointestinal Medicine Showa General HospitalTokyo 187-8510Japan

Russell bodies are globular and eosinophilic inclusion bodies in the cytoplasm of mature plasma cells.Plasma cells whose cytoplasm is filled with Russell bodies are designated as mott cells.Russell body duodenitis(RBD) is a unique form of chronic duodenitis that is characterized by infiltration of numerous mott cells.RBD is very rare;only two cases have been reported to date.In this paper,we report a case of RBD in a patient with retroperitoneal metastasis of ureteral cancer.A 77-year-old man was admitted to our hospital complaining of appetite loss,vomiting,and upper abdominal distension.He had undergone left nephroureterectomy for ureteral cancer 4 years earlier.Upper digestive tract endoscopy revealed edema,stenosis,and punctate redness of the mucosa of the duodenum,and a biopsy was performed.Histological analysis showed that numerous mott cells had infiltrated the lamina propria mucosae,and the condition was diagnosed as RBD.A mass lesion in the retroperitoneum adjacent to the duodenum was detected by abdominal computed tomography,and was diagnosed as metastatic urothelial carcinoma by biopsy.It is possible that chemokines produced by tumor cells caused RBD in this case.

关键词： Russell body Duodenitis Ureteral cancer mott cells Plasma cells

A case of mucosa-associated lymphoid tissue lymphoma of the gastrointestinal tract showing extensive plasma cell differentiation with prominent Russell bodies

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World Journal of Clinical Cases 2013年第5期1卷 176-180页

作者： Keita Kai Masaharu Miyahara Yasunori Tokuda Shinich Kido Masanori Masuda Yukari Takase Osamu Tokunaga Departments of Pathology and Microbiology Saga University Faculty of MedicineSaga 849-8501 Japan Department of Internal Medicine Karatsu Red-Cross HospitalSaga 849-8501 Japan Department of Pathology Karatsu Red-Cross HospitalSaga 849-8501 Japan

A 73-year-old Japanese woman was hospitalized for detailed examination of nausea, diarrhea and loss of appetite. Atypical erosion in the ileum was found on endoscopy. Biopsy of this erosion showed proliferation of cells containing numerous Russell bodies. Differential diagnoses considered were Russell body enteritis, crystal-storing histiocytosis, mott cell tumor, immunoproliferative small intestinal disease(IPSID) and mucosaassociated lymphoid tissue(MALT) lymphoma. The cells containing prominent Russell bodies showed diffuse positivity for CD79 a and CD138, but negative results for CD20, CD3, UCHL-1, CD38 and CD68. Russell bodies were diffusely positive for lambda light chain, but negative for kappa light chain, and immunoglobulin(Ig)G, Ig A and Ig M. Based on these findings, Russell body enteritis, crystal-storing histiocytosis and IPSID were ruled out. As the tumor formed no mass lesions and was restricted to the gastrointestinal tract, MALT lymphoma with extensive plasma cell differentiation was finally diagnosed. The patient showed an unexpectedly aggressive clinical course. The number of atypical lymphocytes in peripheral blood gradually increased and T-prolymphocytic leukemia(T-PLL) emerged. The patient died of T-PLL 7 mo after admission. Autopsy was not permitted.

关键词： Mucosa-associated lymphoid tissue lymphoma Plasmacytoma Russell body mott cell tumor T-prolymphocytic leukemia