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New Energy-Based decoherence Correction Approaches for Trajectory Surface Hopping

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Chinese Journal of Chemical Physics 2020年第5期33卷 603-612,I0079页

作者： Bing-yang Xiao Jia-bo Xu Lin-jun Wang Center for Chemistry of Novel&High-Performance Materials and Department of ChemistryZhejiang UniversityHangzhou 310027China

Inspired by the branching corrected surface hopping(BCSH)method[*** and ***,***.150,164101(2019)],we present two new decoherence time formulas for trajectory surface *** the proposed linear and exponential formulas characterize the decoherence time as functions of the energy difference between adiabatic states and correctly capture the decoherence effect due to wave packet reflection as predicted by *** relevant parameters are trained in a series of 200 diverse models with different initial nuclear momenta,and the exact quantum solutions are utilized as *** demonstrated in the three standard Tully models,the two new approaches exhibit significantly higher reliability than the widely used counterpart algorithm while holding the appealing efficiency,thus promising for nonadiabatic dynamics simulations of general systems.

关键词： Trajectory surface hopping decoherence Nonadiabatic dynamics

Intensity-independent molecular rotational decoherence lifetimes measured with mean wavelength shifts of femtosecond pulses

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Chinese Optics Letters 2018年第12期16卷 6-10页

作者： Hongqiang Xie Guihua Li Jinping Yao Wei Chu.Zhiming Chen and Ya Cheng School of Science East China University of Technology State Key Laboratory of High Field Laser Physics Shanghai Institute of Optics and Fine MechanicsChinese Academy of Sciences School of Science East China Jiaotong University Collaborative Innovation Center of Extreme Optics Shanxi University

We report on an experimental investigation on the dynamic decoherence process of molecular rotational wavepackets during femtosecond laser filamentation based on time-dependent mean wavelength shifts of a weak probe pulse. Details of periodic revival structures of transient alignment can be readily obtained from the measured shifted spectra due to the periodic modulation of the molecular refractive index. Using the method, we measured decoherence lifetimes of molecular rotational wavepackets in N2and O2under different experimental conditions. Our results indicate that decoherence lifetimes of molecular rotational wavepackets are primarily determined by the relative population of rotational states in the wave packet and intermolecular collisions,rather than the focusing intensity.

关键词： molecular rotational measured decoherence wavepackets

Measurement of the decoherence of a mesoscopic superposition of motional states of a trapped ion

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Chinese Physics B 2004年第10期13卷 1707-1710页

作者：郑仕标 DepartmentofElectronicScienceandAppliedPhysics FuzhouUniversityFuzhou350002China

We propose a scheme to observe the decoherence of a mesoscopic superposition of two coherent states in the motion of a trapped ion. In the scheme the ion is excited by two perpendicular lasers tuned to the ion transition. The decoherence is revealed by the decrease of the correlation between two successive measurements of the internal state of the ion after relevant laser-ion interaction.

关键词： decoherence mesoscopic superposition trapped ion

decoherence of a Damped Anisotropic Harmonic Oscillator under Magnetic Field Effects in a Two-Dimensional Noncommutative Phase-Space

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Journal of Applied Mathematics and Physics 2020年第12期8卷 2801-2823页

作者： Martin Tcoffo Germain Yinde Deuto Issofa Nsangou Armel Azangue Koumetio Lylyane S. Yonya Tchapda Alain G. Tene Research Unit of Condensed Matter Electronics and Signal Processing University of Dschang Dschang Cameroon Centre d’Etude et de Recherche en Agronomie et en Biodiversité FASA Université de Dschang Dschang Cameroun

In this paper, decoherence of a damped anisotropic harmonic oscillator in the presence of a magnetic field is studied in the framework of the Lindblad theory of open quantum systems in noncommutative phase-space. General fundamental conditions that should follow our quantum mechanical diffusion coefficients appearing in the master equation are kindly derived. From the master equation, the expressions of density operator, the Wigner distribution function, the expectation and variance with respect to coordinates and momenta are obtained. Based on these quantities, the total energy of the system is evaluated and simulations show its dependency to phase-space structure and its improvement due to noncommutativity effects and the environmental temperature as well. In addition, we also evaluate the decoherence time scale and show that it increases with noncommutativity phase-space effects as compared to the commutative case. It turns out from simulations that this time scale is significantly improved under magnetic field effects.

关键词： decoherence Noncommutative Phase-Space Lindblad Theory Wigner Distribution

decoherence as an Inherent Characteristic of Quantum Mechanics

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Journal of Modern Physics 2021年第5期12卷 700-729页

作者： Riuji Mochizuki Laboratory of Physics Tokyo Dental College Tokyo Japan

In this study, we show that it is possible to explain the quantum measurement process within the framework of quantum mechanics without any additional postulates. We do not delve into a deep discussion regarding what the measurement problem actually is, and only examine the problems that seem to exist between classical and quantum physics. Relations between quantum and classical equations of motion are briefly reviewed to show that the transition from a superposition of quantum states to an eigenstate, namely, decoherence, is necessary to ensure that the expectation values in quantum mechanics obey the classical equations of motion. Several Bell-type inequalities and the Kochen-Specker theorem are also reviewed to clarify the concepts of nonseparability and counterfactual definiteness in quantum mechanics. The main objective of this study is to show that decoherence is an inherent characteristic of quantum states caused by the quantum uncertainty relation. We conclude that the quantum measurement process can indeed be explained within the framework of pure quantum mechanics. We also show that our conclusion is consistent with the counterfactual indefiniteness of quantum mechanics.

关键词： decoherence Uncertainty Relation Measurement Problem

Thermodynamic Properties and decoherence of a Central Electron Spin of Atom Coupled to an Anti-Ferromagnetic Spin Bath

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Journal of Quantum Information Science 2013年第1期3卷 10-15页

作者： Martin Tchoffo Georges Collince Fouokeng Lukong Cornelius Fai Mathurin Esouague Ateuafack Mesoscopic and Multilayer Structures Laboratory Department of Physics Faculty of Science University of Dschang Dschang Cameroon

The decoherence of a central electron spin of an atom coupled to an anti-ferromagnetic spin bath in the presence of a time varying B-Field (VBF) is investigated applying the Holstein-Primak off and Bloch transformations approaches. The Boltzmann entropy and the specific heat capacity at a given temperature are obtained and show the correlation of the coupling of the spin bath and the electron spin of the central atom. At low frequencies the coherence of the coupled system is dominated by the magnetic field intensity. At low VBF intensity, there is decrease in entropy and heat capacity at increase external magnetic field that show the decoherence suppression of the central electron spin atom. The crossing observed in the specific heat capacity corresponds to the critical field point Bc of the system which represents the point of transition from the anti-ferromagnetic system to the ferromagnetic one.

关键词： Entropy Specific Heat Capacity Varying B-Field decoherence

Quantum Path Predictability for an Electronic Mach-Zehnder Interferometer in Presence of Environment Induced decoherence and Quantum Erasing Process

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Journal of Modern Physics 2016年第9期7卷 892-898页

作者： Samyadeb Bhattacharya Sisir Roy Harish-Chandra Research Institute Allahabad India National Institute of Advanced Studies IISC Campus Bangalore India

In this paper, we have estimated the temperature dependent path predictability for an electronic Mach-Zehnder interferometer. The increment of path predictability can directly be associated with stronger decoherence process. We have also theoretically predicted that placing two detectors in both the paths, which are at the same equilibrium temperature with the system, erases all the memory of path information and hence acts like a quantum eraser.

关键词： Path Predictability Quantum Interference decoherence Open Quantum Systems

Coherence and decoherence Effects on Lasing with o without Population Inversion in a Four-level Atomic System

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Chinese Journal of Lasers 1997年第6期 48-53页

作者： GONG Shangqing DU Side LI Yuan XU Zhizhan(Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences,P.O.Box 800211, Shanghai 201800, China)

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关键词： coherence decoherence lasing without population inversion fourlevel atomic medium

Teleportation of Superposition of Coherent States Using 4-Partite States and Effect of decoherence on Fidelity

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Journal of Quantum Information Science 2012年第4期2卷 123-138页

作者： Shivani A. Kumar H. Prakash N. Chandra Ranjana Prakash Amity Institute of Applied Sciences Amity University Delhi India Department of Physics University of Allahabad Allahabad India

A scheme of teleporting a superposition of coherent states |α> and |-α> using a 4-partite state, a beam splitter and two phase shifters was proposed by N. Ba An (Phys. Rev. A, 68, 022321, 2003). The author concluded that the probability for successful teleportation is only 1/4 in the limit |α|→∞ and 1/2 in the limit |α|→∞. In this paper it is shown that the author’s scheme can be altered slightly so as to obtain an almost perfect teleportation for an appreciable value of |α|2. We find the minimum assured fidelity i.e., the minimum fidelity for an arbitrarily chosen information state, which we write MAF in this paper, for different cases. We also discuss the effect of decoherence on teleportation fidelity. We find that if no photons are counted in both final outputs, MAF, is still nonzero except when there is no decoherence and the initial state (the state to be teleported) is even coherent state. For non-zero photon counts, MAF decreases with increase in |α|2 for low noise. For high noise, however, it increases, attains a maximum value and then decreases with |α|2. The average fidelity depends appreciably on the initial state for low values of |α|2 only.

关键词： Teleportation Entanglement Coherent States decoherence