scholarly journals Experimental critical quantum metrology with the Heisenberg scaling

2021 ◽  
Vol 7 (1) ◽  
Author(s):  
Ran Liu ◽  
Yu Chen ◽  
Min Jiang ◽  
Xiaodong Yang ◽  
Ze Wu ◽  
...  
Keyword(s):  
Energy Gap ◽  
Transverse Magnetic ◽  
Spin Model ◽  
Quantum Metrology ◽  
Critical Systems ◽  
Physical Systems ◽  
Ising Spin ◽  
Experimental Implementation ◽  
Potential Applications ◽  
Theoretical Proposal

AbstractCritical quantum metrology, which exploits quantum critical systems as probes to estimate a physical parameter, has gained increasing attention recently. However, the critical quantum metrology with a continuous quantum phase transition (QPT) is experimentally challenging since a continuous QPT only occurs at the thermodynamic limit. Here, we propose an adiabatic scheme on a perturbed Ising spin model with a first-order QPT. By introducing a small transverse magnetic field, we can not only encode an unknown parameter in the ground state but also tune the energy gap to control the evolution time of the adiabatic passage. Moreover, we experimentally implement the critical quantum metrology scheme using nuclear magnetic resonance techniques and show that at the critical point the precision achieves the Heisenberg scaling as 1/T. As a theoretical proposal and experimental implementation of the adiabatic scheme of critical quantum metrology and its advantages of easy implementation, inherent robustness against decays and tunable energy gap, our adiabatic scheme is promising for exploring potential applications of critical quantum metrology on various physical systems.

scholarly journals A spatio-temporal specification language and its completeness & decidability

2020 ◽  
Vol 9 (1) ◽  
Author(s):  
Tengfei Li ◽  
Jing Liu ◽  
Haiying Sun ◽  
Xiang Chen ◽  
Lipeng Zhang ◽  
...  
Keyword(s):  
Intelligent Transportation System ◽  
Cyber Physical Systems ◽  
Specification Language ◽  
Finite Model ◽  
Critical Systems ◽  
Physical Systems ◽  
Spatial Objects ◽  
Temporal Properties ◽  
Spatio Temporal ◽  
Temporal Specification

AbstractIn the past few years, significant progress has been made on spatio-temporal cyber-physical systems in achieving spatio-temporal properties on several long-standing tasks. With the broader specification of spatio-temporal properties on various applications, the concerns over their spatio-temporal logics have been raised in public, especially after the widely reported safety-critical systems involving self-driving cars, intelligent transportation system, image processing. In this paper, we present a spatio-temporal specification language, STSL PC, by combining Signal Temporal Logic (STL) with a spatial logic S4 u, to characterize spatio-temporal dynamic behaviors of cyber-physical systems. This language is highly expressive: it allows the description of quantitative signals, by expressing spatio-temporal traces over real valued signals in dense time, and Boolean signals, by constraining values of spatial objects across threshold predicates. STSL PC combines the power of temporal modalities and spatial operators, and enjoys important properties such as finite model property. We provide a Hilbert-style axiomatization for the proposed STSL PC and prove the soundness and completeness by the spatio-temporal extension of maximal consistent set and canonical model. Further, we demonstrate the decidability of STSL PC and analyze the complexity of STSL PC. Besides, we generalize STSL to the evolution of spatial objects over time, called STSL OC, and provide the proof of its axiomatization system and decidability.

scholarly journals Review of Design Elements within Power Infrastructure Cyber–Physical Test Beds as Threat Analysis Environments

Energies ◽  
2021 ◽  
Vol 14 (5) ◽  
pp. 1409
Author(s):  
Bjorn Vaagensmith ◽  
Vivek Kumar Singh ◽  
Robert Ivans ◽  
Daniel L. Marino ◽  
Chathurika S. Wickramasinghe ◽  
...  
Keyword(s):  
User Interfaces ◽  
Fault Injection ◽  
Modern Society ◽  
Physical Test ◽  
Design Elements ◽  
Physical Systems ◽  
Threat Analysis ◽  
Model Based Testing ◽  
Potential Applications ◽  
Performance Validation

Cyber–physical systems (CPSs) are an integral part of modern society; thus, enhancing these systems’ reliability and resilience is paramount. Cyber–physical testbeds (CPTs) are a safe way to test and explore the interplay between the cyber and physical domains and to cost-effectively enhance the reliability and resilience of CPSs. Here a review of CPT elements, broken down into physical components (simulators, emulators, and physical hardware), soft components (communication protocols, network timing protocols), and user interfaces (visualization-dashboard design considerations) is presented. Various methods used to validate CPS performance are reviewed and evaluated for potential applications in CPT performance validation. Last, initial simulated results for a CPT design, based on the IEEE 33 bus system, are presented, along with a brief discussion on how model-based testing and fault–injection-based testing (using scaling and ramp-type attacks) may be used to help validate CPT performance.

scholarly journals Quad-Band Plasmonic Perfect Absorber for Visible Light with a Patchwork of Silicon Nanorod Resonators

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 1954 ◽  
Author(s):  
Can Cao ◽  
Yongzhi Cheng
Keyword(s):  
Visible Light ◽  
Transverse Electric ◽  
Transverse Magnetic ◽  
Localized Surface Plasmon ◽  
Perfect Absorber ◽  
Absorption Properties ◽  
Perfect Absorption ◽  
Potential Applications ◽  
Polarization Insensitive ◽  
Band Absorption

In this paper, a plasmonic perfect absorber (PPA) based on a silicon nanorod resonator (SNRR) for visible light is proposed and investigated numerically. The proposed PPA is only a two-layer nanostructure consisting of a SNRR periodic array and metal substrate. The perfect absorption mainly originates from excitation of the localized surface plasmon resonance (LSPR) mode in the SNRR structure. The absorption properties of this design can be adjusted by varying the radius (r) and height (h) of the SNRR structure. What is more, the stronger quad-band absorption can be achieved by combing four different radius of the SNRR in one period as a super unit-cell. Numerical simulation indicates that the designed quad-band PPA can achieve the absorbance of 99.99%, 99.8%, 99.8%, and 92.2% at 433.5 THz, 456 THz, 482 THz, and 504.5 THz, respectively. Further simulations show that the proposed PPA is polarization-insensitive for both transverse electric (TE) and transverse magnetic (TM) modes. The proposed PPA can be a desirable candidate for some potential applications in detecting, sensing, and visible spectroscopy.

scholarly journals Ising formulations of some graph-theoretic problems in psychological research: models and methods

2020 ◽  
Author(s):  
Michael Brusco ◽  
Clintin Davis-Stober ◽  
Douglas Steinley
Keyword(s):  
Paired Comparison ◽  
Psychological Research ◽  
Directed Acyclic Graphs ◽  
Spin Model ◽  
Mathematical Psychology ◽  
Linear Ordering ◽  
Spin Models ◽  
Graph Theoretic ◽  
Algorithm Efficiency ◽  
Ising Spin

It is well known that many NP-hard and NP-complete graph-theoretic problems can be formulated and solved as Ising spin models. We discuss several problems that have a particular history in mathematical psychology, most notably max-cut clustering, graph coloring, a linear ordering problem related to paired comparison ranking and directed acyclic graphs, and the problem of finding a minimum subset of points necessary to contain another point within a convex hull. New Ising spin models are presented for the latter two problems. In addition, we provide MATLAB software programs for obtaining solutions via enumeration of all spin ensembles (when computationally feasible) and simulated annealing. Although we are not advocating that the Ising spin model is the preferred approach for formulation and solution of graph-theoretic problems on conventional digital computers, it does provide a unifying framework for these problems. Moreover, recent progress in the development of quantum computing architecture has shown that Ising spin models can afford enormous improvements in algorithm efficiency when implemented on these platforms, which may ultimately lead to widespread use of the methodology in the future.

scholarly journals Influence of γ-Irradiation on the Structural Properties of Indium Monoselenide Crystals

2016 ◽  
Vol 6 (6) ◽  
pp. 1264-1268
Author(s):  
F. A. Al-Mufadi ◽  
A. El-Taher ◽  
G. A. Gamal
Keyword(s):  
Structural Properties ◽  
Energy Gap ◽  
Γ Irradiation ◽  
Layered Semiconductor ◽  
X Ray ◽  
Detailed Structural Analysis ◽  
Peak Broadening ◽  
Potential Applications ◽  
Vertical Bridgman ◽  
Special Modification

Indium monoselenide (InSe) which is a layered semiconductor whose energy gap is 1.24 eV has received attention because of its potential applications in optoelectronic devices. In the present work n-type InSe crystals were grown by a special modification of the vertical Bridgman technique. X-ray Diffraction (XRD) patterns showed that all samples were single phased InSe. The crystals were irradiated with 100 - 500 KGy to reveal the influence of irradiation on the structural properties of the samples. Detailed structural analysis was done by Scherrerr’s procedures, x-ray peak broadening and Williamson–Hall plot methods to evaluate the crystalline sizes and lattice strain. Also from the relations between the irradiation dose and the deformation of the lattice parameters we could investigate and discuss the mutation of the dislocation density, grain size, microstrain and crystallinity of the grown crystals. Striking results are found due to irradiation in the present study for the first time.

Cyber Physical Security Solutions for Pervasive Health Monitoring Systems

2013 ◽  
pp. 143-162 ◽  
Author(s):  
Krishna K. Venkatasubramanian ◽  
Sidharth Nabar ◽  
Sandeep K. S. Gupta ◽  
Radha Poovendran
Keyword(s):  
Health Monitoring ◽  
Key Agreement ◽  
Cyber Physical Systems ◽  
Monitoring Systems ◽  
Critical Systems ◽  
Physical Security ◽  
Physical Systems ◽  
Physiological Signal ◽  
Health Monitoring Systems ◽  
Pervasive Health

With a rapidly aging population, the healthcare community will soon face severe medical personnel shortage and rising costs. Pervasive Health Monitoring Systems (PHMS) can help alleviate this situation. PHMS provides continuous real-time monitoring of a person’s health using a (usually wireless) network of medical and ambient sensors/devices on the host (patients), called Body Area Networks (BANs). The sensitive nature of health information collected by PHMS mandates that patient’s privacy be protected by securing the medical data from any unauthorized access. The authors’ approach for addressing these issues focuses on a key observation that PHMS are cyber-physical systems (CPS). Cyber-physical systems are networked, computational platforms, deeply embedded in specific physical processes for monitoring and actuation purposes. In this work, they therefore present a novel perspective on securing PHMS, called Cyber Physical Security (CYPSec) solutions. CYPSec solutions are environmentally-coupled security solutions, which operate by combining traditional security primitives along with environmental features. Its use results in not only secure operation of a system but also the emergence of additional “allied” properties which enhance its overall capabilities. The principal focus of this chapter is the development of a new security approach for PHMS called CYPsec that leverages their cyber-physical nature. The authors illustrate the design issues and principals of CYPSec through two specific examples of this generic approach: (a) Physiological Signal based key Agreement (PSKA) is designed to enable automated key agreement between sensors in the BAN based on physiological signals from the body; and (b) Criticality Aware Access Control (CAAC) which has the ability to provide controlled opening of the system for emergency management. Further, they also discuss aspects such as altered threat-model, increased complexity, non-determinism, and mixed critical systems, that must be addressed to make CYPSec a reality.

Effects of Magnetic Fields on PN Junctions in Piezomagnetic–Piezoelectric Semiconductor Composite Fibers

2020 ◽  
Vol 12 (08) ◽  
pp. 2050085
Author(s):  
Chao Liang ◽  
Chunli Zhang ◽  
Weiqiu Chen ◽  
Jiashi Yang
Keyword(s):  
Magnetic Field ◽  
Composite Fiber ◽  
Transverse Magnetic ◽  
Piezoelectric Semiconductor ◽  
One Dimensional ◽  
Current Voltage ◽  
Potential Applications ◽  
Multiferroic Composite ◽  
The Magnetic Field ◽  
Current Voltage Relation

We study the electromechanical and electrical behaviors of a PN junction in a multiferroic composite fiber, consisting of a piezoelectric semiconductor (PS) layer between two piezomagnetic (PM) layers, under a transverse magnetic field. Based on the derived one-dimensional model for multiferroic composite semiconductor structures, we obtain the linear analytical solution for the built-in potential and electric field in the junction when there is no applied voltage between the two ends of the fiber. When a bias voltage is applied over the two ends of the fiber, a nonlinear numerical analysis is performed for the current–voltage relation. Both a homogeneous junction with a uniform PS layer and a heterogeneous junction with two different PSs on different sides of the junctions are studied. It is found that overall the homogeneous junction is essentially unaffected by the magnetic field, and the heterojunction is sensitive to the magnetic field with potential applications in piezotronics.

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