DYNAMICS OF ENTANGLEMENT IN HEISENBERG CHAINS WITH ASYMMETRIC DZYALOSHINSKII–MORIYA INTERACTIONS

2011 ◽  
Vol 09 (02) ◽  
pp. 751-761 ◽  
Author(s):  
Y. Z. WU ◽  
J. REN ◽  
X. F. JIANG
Keyword(s):  
Nearest Neighbor ◽  
Time Interval ◽  
Dm Interaction ◽  
Large N ◽  
Heisenberg Chains

Dynamics of the nearest-neighbor concurrence and the block–block entanglement in closed Heisenberg chains with Dzyaloshinskii–Moriya (DM) interactions are simulated numerically. It is found that the nearest-neighbor concurrence and the block–block entanglement can be generated dynamically from an initial antiferromagnetic (AF) state, and DM interactions will enhance the amplitude of oscillation of concurrence and that of block–block entanglement. Furthermore, dynamics of block–block entanglement SL in the chain with even number spins is coincident with the dynamics of SN - L for D = 0. However, with the consideration of DM interactions, the evolution of SL will not be consistent with that of SN - L for the chain with odd number spins. In a given time interval, the maximal value of the generated nearest-neighbor concurrence [Formula: see text] will first decrease with the increase of chain's length, then oscillate with the increase of N. The maximal value and the minimal value of the oscillation becomes stable for a large N, and [Formula: see text] of the chain with odd spins is larger than that of the chain with even spins for a large N. The influence of DM interaction on the value of [Formula: see text] becomes unobvious with the increase of chain's length.

A NOVEL SMALL-WORLD NETWORK MODEL: KEEPING CONNECTIVITY WITHOUT ADDING EDGES

2008 ◽  
Vol 22 (29) ◽  
pp. 5229-5234 ◽  
Author(s):  
XUHUA YANG ◽  
BO WANG ◽  
WANLIANG WANG ◽  
YOUXIAN SUN
Keyword(s):  
Network Model ◽  
Regular Ring ◽  
Nearest Neighbor ◽  
Small World ◽  
Clustering Coefficient ◽  
The Novel ◽  
Small World Network ◽  
Characteristic Path Length ◽  
Large N ◽  
Novel Model

Considering the problems of potentially generating a disconnected network in the WS small-world network model [Watts and Strogatz, Nature393, 440 (1998)] and of adding edges in the NW small-world network model [Newman and Watts, Phys. Lett. A263, 341 (1999)], we propose a novel small-world network model. First, generate a regular ring lattice of N vertices. Second, randomly rewire each edge of the lattice with probability p. During the random rewiring procedure, keep the edges between the two nearest neighbor vertices, namely, always keep a connected ring. This model need not add edges and can maintain connectivity of the network at all times in the random rewiring procedure. Simulation results show that the novel model has the typical small-world properties which are small characteristic path length and high clustering coefficient. For large N, the model is approximately equal to the WS model. For large N and small p, the model is approximately equal to the WS model or the NW model.

PAIRWISE ENTANGLEMENT IN THE N-QUBIT XX MODEL WITH DZYALOSHINSKI–MORIYA INTERACTION AND MAGNETIC FIELD

2011 ◽  
Vol 25 (16) ◽  
pp. 2135-2148
Author(s):  
BIN ZHOU
Keyword(s):  
Magnetic Field ◽  
Critical Temperature ◽  
Magnetic Fields ◽  
Nearest Neighbor ◽  
Zero Temperature ◽  
Thermal Entanglement ◽  
Dm Interaction ◽  
Xx Model ◽  
Moriya Interaction

In this paper, we investigate the role of Dzyaloshinski–Moriya (DM) interaction in the pairwise entanglement in the three- and four-qubit XX models with magnetic field. In the four-qubit model, the pairwise entanglements of two nearest-neighbor qubits and two next-neighbor qubits are investigated, respectively. The dependences of the critical temperature at which the pairwise thermal entanglement disappears on DM interaction and magnetic fields are studied in details. At zero temperature, the entanglement can undergo sudden changes with adjustment of the parameters, and the general results of the concurrence are obtained in all cases.

scholarly journals SPACE–TIME UNCERTAINTY PRINCIPLE FROM BREAKDOWN OF TOPOLOGICAL SYMMETRY

1998 ◽  
Vol 13 (03) ◽  
pp. 203-209 ◽  
Author(s):  
ICHIRO ODA
Keyword(s):  
Uncertainty Principle ◽  
Uncertainty Relation ◽  
Space Time ◽  
Topological Quantum Field Theory ◽  
Time Interval ◽  
Quantum Field ◽  
Higher Symmetry ◽  
Time Uncertainty ◽  
Topological Quantum ◽  
Large N

Starting from topological quantum field theory, we derive space–time uncertainty relation with respect to the time interval and the spatial length proposed by Yoneya through breakdown of topological symmetry in the large-N matrix model. This work suggests that the topological symmetry might be an underlying higher symmetry behind the space–time uncertainty principle of string theory.

Abstract 148: The Time Interval Between the R-Wave and Maximum Aortic Pressure Affects Chest Compression Hemodynamics in a Swine Model of Pseudo Electro-Mechanical Dissociation

Circulation ◽  
2018 ◽  
Vol 138 (Suppl_2) ◽  
Author(s):  
Joshua W Lampe ◽  
Karen L Moodie ◽  
Jeffrey R Gould ◽  
Christopher L Kaufman ◽  
Norman A Paradis
Keyword(s):  
Chest Compression ◽  
Nearest Neighbor ◽  
Aortic Pressure ◽  
The Other ◽  
Time Interval ◽  
Swine Model ◽  
Coronary Perfusion ◽  
Ventricular Contraction ◽  
Mechanical Dissociation ◽  
Blood Pressures

Introduction: The prevalence of pseudo electro-mechanical dissociation (P-EMD) as an initial cardiac arrest state is increasing. P-EMD manifests a weak ventricular contraction, which is not sufficient to sustain life. However, the presence of a weak ventricular contraction may lead to interference with or synergy with the blood flow generated by a chest compression depending on the time interval between the compression and ventricular contraction. Hypothesis: We hypothesize that the interval between a chest compression and the ventricular contraction during P-EMD will influence the hemodynamics created by the chest compression. Methods: Using our well established hypoxic P-EMD model, we measured blood pressures and ECG during mechanical chest compression (100 CPM, 2”). A nearest-neighbor analysis determined the time interval between the R-wave and the peak aortic pressure, defined as t peak AOP - t Rwave . Peak aortic pressures that had more than one R-wave nearest neighbor were excluded. 1,497 chest compressions were analyzed. Intervals were divided into quartiles, and hemodynamic parameters were compared between the quartiles using a repeated measure ANOVA with Bonferroni correction. Results: Interval (int) quartiles were defined as: Q1: int > 100 ms; Q2: 100 ms > int > 0.0 ms; Q3: 0.0ms > int > -90 ms; Q4: - 90 ms > int. Mean arterial pressures (MAP) in mmHg as a function of interval are: Q1: 33.8±0.6; Q2: 41.1±0.6; Q3: 38.3±0.6; Q4: 33.1±0.6. The MAP value for compressions with an interval in Q2 was higher than the other quartiles ( p > 0.05). Coronary perfusion pressures (CPP) in mmHg as a function of interval are: Q1: 11.7±0.5; Q2: 15.3±0.5; Q3: 15.6±0.5; Q4: 12.9±0.5. The CPP values for compressions with an interval in Q2 or Q3 was higher than the other quartiles ( p > 0.05). Conclusions: The interval between the R-wave and the peak aortic pressure generated by a chest compression has a significant effect on the resulting hemodynamics. Shorter intervals, both positive and negative are associated with improved blood pressures during resuscitation from P-EMD. These data suggest that delivery of standard CPR during P-EMD can result in a mix of effective and less effective compressions.

scholarly journals The Spatio-Temporal Characteristics and Influencing Factors of Covid-19 Spread in Shenzhen, China—An Analysis Based on 417 Cases

2020 ◽  
Vol 17 (20) ◽  
pp. 7450
Author(s):  
Shirui Liu ◽  
Yaochen Qin ◽  
Zhixiang Xie ◽  
Jingfei Zhang
Keyword(s):  
Nearest Neighbor ◽  
High Mobility ◽  
Time Interval ◽  
Linear Regression Method ◽  
Index Method ◽  
Temporal Characteristics ◽  
Global Pandemic ◽  
Ellipse Method ◽  
Long Time ◽  
Spatio Temporal

The global pandemic of COVID-19 has made it the focus of current attention. At present, the law of COVID-19 spread in cities is not clear. Cities have long been difficult areas for epidemic prevention and control because of the high population density, high mobility of people, and high frequency of contacts. This paper analyzed case information for 417 patients with COVID-19 in Shenzhen, China. The nearest neighbor index method, kernel density method, and the standard deviation ellipse method were used to analyze the spatio-temporal characteristics of the COVID-19 spread in Shenzhen. The factors influencing that spread were then explored using the multiple linear regression method. The results show that: (1) The development of COVID-19 epidemic situation in Shenzhen occurred in three stages. The patients showed significant hysteresis from the onset of symptoms to hospitalization and then to diagnosis. Prior to 27 January, there was a relatively long time interval between the onset of symptoms and hospitalization for COVID-19; the interval decreased thereafter. (2) The epidemic site (the place where the patient stays during the onset of the disease) showed an agglomeration in space. The degree of agglomeration constantly increased across the three time nodes of 31 January, 14 February, and 22 February. The epidemic sites formed a “core area” in terms of spatial distribution and spread along the “northwest–southeast” direction of the city. (3) Economic and social factors significantly impacted the spread of COVID-19, while environmental factors have not played a significant role.

scholarly journals Skyrmion Crystals and Phase Transitions in Magneto-Ferroelectric Superlattices: Dzyaloshinskii–Moriya Interaction in a Frustrated J1 − J2 Model

Symmetry ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 26 ◽  
Author(s):  
Ildus F. Sharafullin ◽  
Hung T. Diep
Keyword(s):  
Magnetic Field ◽  
Phase Transition ◽  
Applied Magnetic Field ◽  
Nearest Neighbor ◽  
Lattice Structure ◽  
Magnetic Layer ◽  
Steepest Descent Method ◽  
Spin Configuration ◽  
Dm Interaction ◽  
Ferroelectric Layer

The formation of a skyrmion crystal and its phase transition are studied, taking into account the Dzyaloshinskii–Moriya (DM) interaction at the interface between a ferroelectric layer and a magnetic layer in a superlattice. Frustration is introduced in both magnetic and ferroelectric films. The films have a simple cubic lattice structure. The spins inside the magnetic layers are Heisenberg spins interacting with each other via nearest-neighbor (NN) exchange J m and next-nearest-neighbor (NNN) exchange J 2 m . The polarizations in the ferroelectric layers are assumed to be of Ising type with NN and NNN interactions J f and J 2 f . At the magnetoelectric interface, a DM interaction J m f between spins and polarizations is supposed. The spin configuration in the ground state is calculated by the steepest descent method. In an applied magnetic field H perpendicular to the layers, we show that the formation of skyrmions at the magnetoelectric interface is strongly enhanced by the frustration brought about by the NNN antiferromagnetic interactions J 2 m and J 2 f . Various physical quantities at finite temperatures are obtained by Monte Carlo simulations. We show the critical temperature, the order parameters of magnetic and ferroelectric layers as functions of the interface DM coupling, the applied magnetic field, and J 2 m and J 2 f . The phase transition to the disordered phase is studied in detail.

scholarly journals The spatiotemporal evolution of ancient cities from the late Yangshao to Xia and Shang Dynasties in the Central Plains, China

2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Lijie Yan ◽  
Ruixia Yang ◽  
Peng Lu ◽  
Fei Teng ◽  
Xia Wang ◽  
...  
Keyword(s):  
Nearest Neighbor ◽  
State Level ◽  
Time Interval ◽  
Gravity Center ◽  
Central Plains ◽  
Ancient City ◽  
Database Technology ◽  
Chinese State ◽  
Social Organizational ◽  
Average Size

AbstractThe Central Plains has a long history, rich culture, unique geographical advantages, and profound cultural heritage. The occurrence of ancient cities in the Central Plains marks the formation of Chinese state-level societies. The number, size, and distribution of ancient cities have changed greatly from the late Yangshao to the Xia and Shang Dynasties, which reflects the evolution of settlement and social organization. In this study, Geographic Information System (GIS) spatial database technology was used to establish a spatiotemporal database of ancient cities in the late Yangshao, Longshan, as well as Xia and Shang Dynasties in the Central Plains. This paper uses GIS spatial analysis technology to analyze the relationship between the ancient city distribution and the geographical environment, as well as the evolution of ancient city's shapes and sizes. Furthermore, by using the method of the nearest neighbor distance and gravity center analysis, this paper discusses the agglomeration characteristics and gravity center evolution of ancient cities. The results show that: (1) Most of the ancient cities were distributed in areas below 500 m and within 3 km from the river during the time interval from the late Yangshao to Xia and Shang Dynasties; (2) The shape of the ancient cities gradually changed from circles to squares in the Central Plains, which became a unified model for the later ancient city design; (3) The sizes of the 18 ancient cities in the Yangshao period shared high similarity, with an average area of 20 hectares. The sizes of 24 ancient cities in the Longshan period increased significantly, with an average of 39 hectares. During the Xia and Shang Dynasties, there were 22 ancient cities with an average size of 340 hectares, and the grade of sizes became obvious, marking the entrance into Chinese state-level societies; (4) Cities were scattered in the decentralized pattern during the late Yangshao and Longshan periods, whereas they became agglomerative in Xia and Shang Dynasties. This reflects the evolution of the spatial scopes and social organizational forms; and (5) From the late Yangshao to Xia and Shang Dynasties, the gravity center of ancient cities moved around the Songshan Mountain from the northwest to the southeast and again to the northeast.

THE EFFECT OF DIFFERENT DZYALOSHINSKII–MORIYA INTERACTIONS ON TELEPORTATION VIA A TWO-QUBIT HEISENBERG CHAIN

2010 ◽  
Vol 24 (04n05) ◽  
pp. 461-473
Author(s):  
TAO CHEN ◽  
CHUAN-JIA SHAN ◽  
YAN-XIA HUANG ◽  
TANG-KUN LIU ◽  
JIN-XING LI
Keyword(s):  
Coupling Coefficient ◽  
Coupling Parameter ◽  
Exchange Constant ◽  
Thermal Entanglement ◽  
Initial State ◽  
Dm Interaction ◽  
Maximum Value ◽  
Entanglement Teleportation ◽  
Xxz Chain ◽  
Heisenberg Chains

Thermal entanglement of a two-qubit Heisenberg XXZ chain in the presence of different Dzyaloshinskii–Moriya (DM) anisotropic antisymmetric interactions and entanglement teleportation using two independent Heisenberg chains as quantum channel are investigated. It is found that the anisotropic coupling coefficient Jz (z-component exchange constant) and DM interactions can excite the entanglement, and x-component DM interaction Dx has a more remarkable influence than the z-axis DM interaction Dz for exchange constant J > 0 (antiferromagnetic) case, which is contrary to coupling coefficient J < 0 (ferromagnetic) case. The output entanglement and fidelity increase with increasing z-axis coupling parameter Jz for both the antiferromagnetic J > 0 case and ferromagnetic J < 0 case. By introducing the different DM interactions, it is superior to teleportate initial state by using the Dz interaction in the model for J > 0 case. But for J < 0 case, the Dx interaction is better, and the output concurrence and fidelity can reach the maximum value 1 with suitable Dx.

Minimal Clustering of Injection-Induced Earthquakes Observed with a Large-n Seismic Array

2020 ◽  
Vol 110 (5) ◽  
pp. 2005-2017 ◽  
Author(s):  
Elizabeth S. Cochran ◽  
Alexander Wickham-Piotrowski ◽  
Kilian B. Kemna ◽  
Rebecca M. Harrington ◽  
Sara L. Dougherty ◽  
...  
Keyword(s):  
Nearest Neighbor ◽  
Seismic Array ◽  
Seismic Survey ◽  
Single Event ◽  
Induced Earthquakes ◽  
Injection Wells ◽  
Independent Events ◽  
Large N ◽  
Aftershock Sequences ◽  
Stress Changes

ABSTRACT The clustering behavior of injection-induced earthquakes is examined using one month of data recorded by the LArge-n Seismic Survey in Oklahoma (LASSO) array. The 1829-node seismic array was deployed in a 25  km×32  km area of active saltwater disposal in northern Oklahoma between 14 April and 10 May 2016. Injection rates in the study area are nearly constant around the time of the deployment. We develop a local magnitude (ML) equation for the region and estimate magnitudes for 1104 earthquakes recorded by the deployment. The determined earthquake magnitudes range from ML 0.01 to 3.0. The majority of earthquakes occurred between 1.5 and 5.5 km depth, and the shallowest earthquake depths overlap with the base of injection wells at depths between 1.5 and 2.5 km. We compute focal mechanisms of the largest events (ML&gt;2.0), and find a mix of normal- and strike-slip-faulting types. Earthquakes occur regularly in time during the deployment, but are not evenly distributed in space across the study area, that is, they are spatially clustered. Analysis of the nearest-neighbor distances in the space–time–magnitude domain shows the seismicity is dominated by single-event clusters (i.e., independent events). This high proportion of single-event clusters compared with multievent clusters has been previously noted for induced events at geothermal sites. When clustering occurs, the number of events in a cluster is typically small. We observe only four clusters with 10 or more events. For these larger clusters, we find equivalent numbers of foreshocks and aftershocks; however, the foreshock sequences are significantly longer in duration lasting days to tens of days, while aftershock sequences are observed only on the order of one day. The minimal clustering observed for events in the LASSO array suggests that the majority of events are being directly driven by stress changes due to local saltwater disposal.

Sign in / Sign up

Export Citation Format

Share Document