Entropy squeezing and coherence for a non-Markovian dissipative qubit system

2019 ◽  
Vol 35 (08) ◽  
pp. 2050046
Author(s):  
K. Berrada
Keyword(s):  
Quantum Coherence ◽  
Photonic Band Gap ◽  
Dynamical Behavior ◽  
Partial Coherence ◽  
Model Parameters ◽  
Entropy Squeezing ◽  
Qubit System ◽  
The Impact ◽  
Photonic Band ◽  
Gap Width

We examine the impact of the non-Markovian environment on the dynamical behavior of the quantum coherence and entropy squeezing considering a two-level atomic system (qubit) immersed in a reservoir with zero-temperature for two types of non-Markovian environments. We consider a cavity little off-resonance with the transition frequency of the qubit and the case of a non-perfect photonic band gap (PBG). We show that the amount of coherence is dependent on the structure of the environment and influenced through the memory effects. We obtain that the delay and revival of the coherence loss might take place by controlling the detuning of the cavity-qubit system. Whereas, a partial coherence trapping occurs in non-ideal PBG and the decrease of the gap width will destroy the coherence. On the other hand, we show the situation for which the squeezing is occurring and enhanced with respect to the main parameters for the system. Finally, we display the monotonic dependence of the quantum coherence and squeezing on the main model parameters.

Preparation and Optical Properties of One-Dimensional Ag/SiOx Photonic Crystal

2014 ◽  
Vol 576 ◽  
pp. 27-31
Author(s):  
Gai Mei Zhang ◽  
Can Wang ◽  
Yan Jun Guo ◽  
Wang Wei ◽  
Xiao Xiang Song
Keyword(s):  
Photonic Crystal ◽  
Band Gap ◽  
Electromagnetic Waves ◽  
Photonic Band Gap ◽  
Incident Angle ◽  
One Dimensional ◽  
The One ◽  
Photonic Band ◽  
Gap Width ◽  
Band Gap Width

The photonic crystal has the property that electromagnetic waves with interval of frequency in photonic band gap (PBG) can not be propagated, so it has important applying and researching value. The traditional one-dimensional photonic crystal is with narrow band gap width, and the reflection within the band is small, especially the band gap is sensitive to the incident angle and the polarization of light. A new photonic band gap (PBG) structure, metallodielectric photonic crystal by inserting metal film in the medium can overcomes the shortcomings mentioned above. The one-dimensional Ag/SiOx photonic crystal was prepared, and theoretical and experimental researches were developed. The results show that photonic band gap appears gradually and the band gap width increase with increasing of period of repeating thickness. With the thickness of Ag film increasing, the band gap width increases, but the starting wavelength of the photonic band gap keeps unchanged. With thickness of SiOx film increasing, the band gap width of photonic band gap also increases, but it is not obvious and starting wavelength increases.

scholarly journals Coherence Trapping in Open Two-Qubit Dynamics

Symmetry ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2445
Author(s):  
Mariam Algarni ◽  
Kamal Berrada ◽  
Sayed Abdel-Khalek ◽  
Hichem Eleuch
Keyword(s):  
Quantum Coherence ◽  
Open Quantum Systems ◽  
Dynamical Behavior ◽  
Quantum Systems ◽  
Completely Positive Maps ◽  
L1 Norm ◽  
Separable States ◽  
System Parameters ◽  
Quantum Dynamical ◽  
Qubit System

In this manuscript, we examine the dynamical behavior of the coherence in open quantum systems using the l1 norm. We consider a two-qubit system that evolves in the framework of Kossakowski-type quantum dynamical semigroups (KTQDSs) of completely positive maps (CPMs). We find that the quantum coherence can be asymptotically maintained with respect to the values of the system parameters. Moreover, we show that the quantum coherence can resist the effect of the environment and preserve even in the regime of long times. The obtained results also show that the initially separable states can provide a finite value of the coherence during the time evolution. Because of such properties, several states in this type of environments are good candidates for incorporating quantum information and optics (QIO) schemes. Finally, we compare the dynamical behavior of the coherence with the entire quantum correlation.

scholarly journals Analysis of COVID-19 Prevention and Control Effects Based on the SEITRD Dynamic Model and Wuhan Epidemic Statistics

2020 ◽  
Vol 17 (24) ◽  
pp. 9309
Author(s):  
Yusheng Zhang ◽  
Liang Li ◽  
Yuewen Jiang ◽  
Biqing Huang
Keyword(s):  
Dynamic Model ◽  
Control Method ◽  
Control Strategies ◽  
Dynamical Behavior ◽  
Model Parameters ◽  
Time Control ◽  
Intervention Measures ◽  
Travel Restrictions ◽  
And Control ◽  
The Impact

Since December 2019, millions of people worldwide have been diagnosed with COVID-19, which has caused enormous losses. Given that there are currently no effective treatment or prevention drugs, most countries and regions mainly rely on quarantine and travel restrictions to prevent the spread of the epidemic. How to find proper prevention and treatment methods has been a hot topic of discussion. The key to the problem is to understand when these intervention measures are the best strategies for disease control and how they might affect disease dynamics. In this paper, we build a transmission dynamic model in combination with the transmission characteristics of COVID-19. We thoroughly study the dynamical behavior of the model and analyze how to determine the relevant parameters, and how the parameters influence the transmission process. Furthermore, we subsequently compare the impact of different control strategies on the epidemic, the variables include intervention time, control duration, control intensity, and other model parameters. Finally, we can find a better control method by comparing the results under different schemes and choose the proper preventive control strategy according to the actual epidemic stage and control objectives.

scholarly journals Bifurcation analysis of a SEIR epidemic system with governmental action and individual reaction

2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Abdelhamid Ajbar ◽  
Rubayyi T. Alqahtani
Keyword(s):  
Transmission Rate ◽  
Dynamical Behavior ◽  
Step Function ◽  
Model Parameters ◽  
Periodic Behavior ◽  
Proposed Model ◽  
Wide Range ◽  
Individual Reaction ◽  
The Impact ◽  
Governmental Action

Abstract In this paper, the dynamical behavior of a SEIR epidemic system that takes into account governmental action and individual reaction is investigated. The transmission rate takes into account the impact of governmental action modeled as a step function while the decreasing contacts among individuals responding to the severity of the pandemic is modeled as a decreasing exponential function. We show that the proposed model is capable of predicting Hopf bifurcation points for a wide range of physically realistic parameters for the COVID-19 disease. In this regard, the model predicts periodic behavior that emanates from one Hopf point. The model also predicts stable oscillations connecting two Hopf points. The effect of the different model parameters on the existence of such periodic behavior is numerically investigated. Useful diagrams are constructed that delineate the range of periodic behavior predicted by the model.

scholarly journals Air-core photonic band-gap fibers: the impact of surface modes

2004 ◽  
Vol 12 (3) ◽  
pp. 394 ◽  
Author(s):  
K. Saitoh ◽  
N. A. Mortensen ◽  
M. Koshiba
Keyword(s):  
Band Gap ◽  
Photonic Band Gap ◽  
Surface Modes ◽  
Air Core ◽  
The Impact ◽  
Photonic Band

Estimating OLED Display Device Lifetime from pixel and screen brightness and its application

2019 ◽  
Vol 2019 (1) ◽  
pp. 331-338 ◽  
Author(s):  
Jérémie Gerhardt ◽  
Michael E. Miller ◽  
Hyunjin Yoo ◽  
Tara Akhavan
Keyword(s):  
Image Processing ◽  
Power Consumption ◽  
Model Parameters ◽  
Display Device ◽  
Image Processing Algorithm ◽  
Pixel Value ◽  
Device Lifetime ◽  
The Impact ◽  
Oled Display

In this paper we discuss a model to estimate the power consumption and lifetime (LT) of an OLED display based on its pixel value and the brightness setting of the screen (scbr). This model is used to illustrate the effect of OLED aging on display color characteristics. Model parameters are based on power consumption measurement of a given display for a number of pixel and scbr combinations. OLED LT is often given for the most stressful display operating situation, i.e. white image at maximum scbr, but having the ability to predict the LT for other configurations can be meaningful to estimate the impact and quality of new image processing algorithms. After explaining our model we present a use case to illustrate how we use it to evaluate the impact of an image processing algorithm for brightness adaptation.

Engineering Electronic Structure to Protect Phase Memory in Molecular Qubits by Minimising Orbital Angular Momentum

2018 ◽  
Author(s):  
Ana Maria Ariciu ◽  
David H. Woen ◽  
Daniel N. Huh ◽  
Lydia Nodaraki ◽  
Andreas Kostopoulos ◽  
...  
Keyword(s):  
Electron Spin ◽  
Quantum Coherence ◽  
Quantum Information Processing ◽  
Pulse Sequences ◽  
Grover Algorithm ◽  
Ligand Shell ◽  
Information Strategies ◽  
Spin Qubit ◽  
Molecular Spin ◽  
The Impact

Using electron spins within molecules for quantum information processing (QIP) was first proposed by Leuenberger and Loss (1), who showed how the Grover algorithm could be mapped onto a Mn12 cage (2). Since then several groups have examined two-level (S = ½) molecular spin systems as possible qubits (3-12). There has also been a report of the implementation of the Grover algorithm in a four-level molecular qudit (13). A major challenge is to protect the spin qubit from noise that causes loss of phase information; strategies to minimize the impact of noise on qubits can be categorized as corrective, reductive, or protective. Corrective approaches allow noise and correct for its impact on the qubit using advanced microwave pulse sequences (3). Reductive approaches reduce the noise by minimising the number of nearby nuclear spins (7-11), and increasing the rigidity of molecules to minimise the effect of vibrations (which can cause a fluctuating magnetic field via spin-orbit coupling) (9,11); this is essentially engineering the ligand shell surrounding the electron spin. A protective approach would seek to make the qubit less sensitive to noise: an example of the protective approach is the use of clock transitions to render spin states immune to magnetic fields at first order (12). Here we present a further protective method that would complement reductive and corrective approaches to enhancing quantum coherence in molecular qubits. The target is a molecular spin qubit with an effective 2S ground state: we achieve this with a family of divalent rare-earth molecules that have negligible magnetic anisotropy such that the isotropic nature of the electron spin renders the qubit markedly less sensitive to magnetic noise, allowing coherent spin manipulations even at room temperature. If combined with the other strategies, we believe this could lead to molecular qubits with substantial advantages over competing qubit proposals.<br>

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