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Transient Quantum Transport in Nanostructures
Published in Klaus D. Sattler, st Century Nanoscience – A Handbook, 2019
Pei-Yun Yang, Yu-Wei Huang, Wei-Min Zhang
The quantum transport theory for these physical systems is based on the following three theoretical approaches. The Landauer-Büttiker approach [7,12,18], because of its simplicity, has often been used to analyze resonant-tunneling diodes [37] and quantum wires [44]. In this approach, electron transport in the device system is simply treated by coherent transport (pure elastic scattering) near thermal equilibrium. However, in order for nanodevices to be functionally operated, it may be subjected to high sourcedrain voltages and high-frequency bandwidths, in far from equilibrium, highly transient, and highly nonlinear regimes. Thus, a more microscopic theory has been developed for quantum transport in terms of nonequilibrium Green functions [10,17,19,23,38,42,52,53] for the device system. Moreover, the device system exchanges the particles, energy, and information with the leads and is thereby a typical open quantum system. The issues of open quantum systems, such as dissipation, fluctuation and decoherence inevitably arise. The third approach, the master equation approach [16,21,22,32,41,47,50,57,58], gets the advantage by describing the device system in terms of the reduced density matrix of open systems.
Nonlinear Dynamics in Quantum Photonic Structures
Published in Joachim Piprek, Handbook of Optoelectronic Device Modeling and Simulation, 2017
Gabriela Slavcheva, Mirella Koleva
Quantum photonics has attracted great interest in recent years. This is due to its potential to revolutionize science and day-to-day life alike through enabling the implementation of faster algorithms, secure transmission of information, vast increase in data storage, and execution of more accurate measurements. One of the major challenges of modeling quantum photonic devices is working out a way of efficient simulation and control of realistic, “open” quantum systems (i.e., allowing for energy to flow in and out of the system) and devices for applications in quantum technologies. For optical quantum information processing to advance beyond demonstration experiments, the development of on-chip capabilities will be essential. Solid-state qubit architectures have emerged as a most promising physical implementation of quantum photonic circuits, taking advantage of the state-of-the-art semiconductor technologies. Reliable, integrated sources of nonclassical light, as well as realization of high-fidelity on-chip readout of solid-state qubits, are a critical requirement for next-generation quantum technologies [7].
Picometer Detection by Adaptive Holographic Interferometry
Published in Klaus D. Sattler, Fundamentals of PICOSCIENCE, 2013
Coupling of a system to the environment leads to a loss of information from the system and leads to a loss of a great deal of observed quantum behavior. The objective of putting an atom in a high finesse cavity in the strong coupling regime is to isolate the system (atom/cavity mode) as much as possible from the environment so that we can observe and exploit highly quantum behavior such as coherent single-photon/single-atom dynamics. In practice, all physical quantum systems are coupled to the environment, and all systems strictly are open quantum systems. Of course, we can always expand our definition of the system to include the modes of the environment, but this is not usually very useful. We may know little or nothing about the evolution of the reservoir modes. There are simply too many to keep track of, and in many cases we only have detailed information on the system Hamiltonian and some information (decay rates) on the coupling of the system to the environment.
Preservation and enhancement of quantum correlations under Stark effect
Published in Journal of Modern Optics, 2023
Nitish Kumar Chandra, Rajiuddin Sk, Prasanta K. Panigrahi
Understanding the impact of decoherence on the quantum system is an essential component of quantum information research. In general, the dynamics of systems interacting with their environment are immensely complicated to solve. The quantum system is classified as either an open quantum system or a closed quantum system based on the type of system-environment interaction. Memory effects are a crucial aspect of non-Markovian quantum behaviour and are implied by information flow from the surrounding environment to the open system. The process is Markovian if the information flow is unidirectional from the open system to the environment. The Markovian process is based on the premise that the system's characteristic times are significantly longer than the environment's and presupposes that there is always a weak coupling between the system and environment. The dynamics of quantum correlations based on Bures norm, Trace norm, entropy, Fisher information, and quantum uncertainty have been investigated under various noise in both Markovian and non-Markovian regimes [19–24].
Dynamics of local quantum uncertainty and local quantum fisher information for a two-qubit system driven by classical phase noisy laser
Published in Journal of Modern Optics, 2021
Up to now, the dynamical behaviour of quantum correlation has been extensively studied and its general theory has been widely developed [11–21]. Interestingly, the dynamics of quantum correlation exhibits different features such as decay, even sudden death and revivals [22–24] due to the environmental effects. Generally, the environmental effects are divided into quantum noisy environment and classical noisy environment. For bipartite open quantum systems in quantum environments, revivals of quantum correlations are attributed to the non-Markovian nature of the environments which can induce the back-action on quantum systems [25–27]. However, this feature referring to classical models of quantum systems fails to capture. This implies that there is no revival of correlations induced by the classical environment [28–30]. Therefore, it is of great significance to study and understand the quantum correlation dynamics in open systems, particularly explore how the characteristics of noise environment influences the dynamical behaviour when the environmental effect is modelled as classical instead of quantum.
Unravelling open-system quantum dynamics of non-interacting Fermions
Published in Molecular Physics, 2018
Decoherence, dephasing and dissipation in large open quantum systems are important phenomena in a broad variety of fields, such as nonadiabatic processes in chemistry and materials science, [1–7], quantum biology [8,9] and quantum information [10,11]. They are commonly described using the concept of the density matrix (DM), which generalises the notion of a wave function as the quantum state descriptor. Despite great success in atomic physics, DM approaches have not found extensive application in the field of large electronic systems, except in cases of small systems, where it is sufficient and possible to address only a small number of electronic states [12–18]. For describing the quantum dynamics of open systems having a large number of electrons and electronic states a different approach is probably needed. Here, it is natural to consider time-dependent (current) density functional theory (TDDFT), based on the Runge–Gross (RG) theorem [19] which simplifies the treatment of the dynamics of interacting electrons by mapping them onto non-interacting Fermions. Extensions of the RG theorem to open systems have indeed appeared [20–25], but the follow-up progress has yet to be achieved, and the main cause for delay is the fact that non-interacting Fermions develop an interaction through the coupling with the bath.1