China
Africa
Explore chapters and articles related to this topic
Progress in Metamaterial and Metasurface Technology and Applications
Published in Pankaj K. Choudhury, Metamaterials, 2021
Quantum information technologies, such as quantum cryptography, quantum information storage and optical quantum computing, demand effective stable sources of single photons and nanostructures to control the quantum dynamics (of these photons) [22]. Transparent metamaterial can aid in enhancing the single-photon radiation over a broad spectral range, the principle of which is discussed in Fig. 1.12. Here single-photon generation is based on coupling diamond nitrogen-vacancy (NV) centers (or silicon-vacancy centers) with a metamaterial having hyperbolic dispersion characteristics in which the enhancement of single-photon emission is due to the presence of metamaterial (may be two orders of magnitude or so). Such single-photon sources may also have applications in nanochemistry to control chemical reactions at the level of individual molecules, biochemical analysis to determine the dynamics of molecular configuration, decoding DNA and so on [23].
Chaotic Interference versus Decoherence: External Noise, State Mixing, and Quantum–Classical Correspondence
Published in Christos H. Skiadas, Charilaos Skiadas, Handbook of Applications of Chaos Theory, 2017
V. Sokolov Valentin, V. Zhirov Oleg
It is very useful to transfer the story on the, generally mixed, quantum states evolution to the language of the phase space [3,4,44]. This elucidates analogy and distinctions between classical and quantum dynamics. A double Fourier transformation of the density matrix W(α*,α;t)=1π2ℏ∫d2ηexp(ηα*ℏ−η*αℏ)ρ^(η*,η;t)=1π2ℏ∫d2ηexp(η*αℏ−ηα*ℏ)Tr[ρ^(t)D^(η)],
The time-dependent density matrix renormalisation group method
Published in Molecular Physics, 2018
Recent advances of the theory about matrix product state (MPS) [59–61] and matrix product operator (MPO) [62,63] have also been incorporated into t-DMRG for more efficient propagation of a quantum state by Haegeman et al. [31,32] and Zaletel et al. [33]. They have shown that, the MPS representation of the t-DMRG wavefunction based on time-dependent variational principle (TDVP) [64,65] or an approximation of the evolution operator in terms of MPO, can greatly simplify the procedures for the time propagation of the many-body wavefunction and does not rely on the form of the Hamiltonians, expanding the toolbox of studying general quantum dynamics for systems beyond 1D topologies and Hamiltonians containing long-range interactions.
The Jahn–Teller effect in the ground electronic state of the tetrafluoromethane cation before dissociation: a promoter of the anisotropic fragmentation
Published in Molecular Physics, 2019
The paper is organised as follows. Section 2 presents the theory regarding the model Hamiltonian and quantum dynamics calculations. Section 3 discusses the results on the calculation of the PESs, determination of various critical points on them and the nuclear motions underlying the structureless and broad first photoelectron band of . Finally, Section 4 concludes the current work.
The importance of initial states in polariton simulation
Published in Molecular Physics, 2023
Jun Zhang, Yong-Chen Xiong, Nan Nan, Wei Li, Wanghuai Zhou
We often assume that the LMI strength is a constant, which is convenient for theoretical considerations and should not cause any problem if we fix the molecule in the cavity. However, we cannot start the simulation with a product state, like , under the dynamics governed by the Hamiltonian in Equation (7), which means that the molecule enters into the cavity at infinite velocity. Actually, the LMI has a space dependence and the Gaussian function is often used to describe the cavity field profile [46,47]. When the molecule moves from outside into the cavity, the LMI felt by the molecule should be space-dependent or equivalently explicitly time-dependent. To mimic the process of molecule flying into the cavity, we use a half-Gaussian function to represent a one-dimensional space-dependent light-matter coupling strength, which reads as where σ is the width of the cavity field, is the maximal intensity when the molecule enters into the cavity, i.e. , which indicates that the molecule does not go outside once it enters into the cavity or it stays forever in the cavity. The intensity profile is shown in Figure 2 with and in atomic units. In our simulations, we assume the molecule moves into the cavity with a constant velocity, that is , is the starting point and fixed with in our simulation. The velocity v is tuned as a parameter to control the adiabaticity of the process. Thus, during our simulation, the LMI is time-dependent and its concrete form is The exact quantum dynamics are performed by using the standard split-operator method [48]. The timestep of the whole simulations is fixed at 0.1 a.u. which makes the total energy is conserved when the light-matter coupling is space-independent. For the space-dependent case, we resimulate with the same initial condition by halving the timestep and the results are consistent with each other.