Time-dependent density functional theory for open systems with a positivity-preserving decomposition scheme for environment spectral functions

Wang, Rulin; Zheng, Xiao; Kwok, YanHo; Xie, Hang; Chen, Guanhua; Yam, ChiYung

doi:10.1063/1.4917172

Cited by 11 publications

(6 citation statements)

References 44 publications

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“…The time-dependent extension of DFT, time-dependent density functional theory (TDDFT), is capable of addressing excited-state properties of electronic systems [224], and, in principle, provides an exact theory for the total current flowing across the device [225]. [230][231][232]. The TDDFT-OS method has been applied to perform atomistic simulations of real-time electron transport through nanojunctions [233].…”

Section: Ectormentioning

confidence: 99%

Local temperatures out of equilibrium

2019

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The temperature of a physical system is operationally defined in physics as "that quantity which is measured by a thermometer" weakly coupled to, and at equilibrium with the system. This definition is unique only at global equilibrium in view of the zeroth law of thermodynamics: when the system and the thermometer have reached equilibrium, the "thermometer degrees of freedom" can be traced out and the temperature read by the thermometer can be uniquely assigned to the system. Unfortunately, such a procedure cannot be straightforwardly extended to a system out of equilibrium, where local excitations may be spatially inhomogeneous and the zeroth law of thermodynamics does not hold. With the advent of several experimental techniques that attempt to extract a single parameter characterizing the degree of local excitations of a (mesoscopic or nanoscale) system out of equilibrium, this issue is making a strong comeback to the forefront of research. In this paper, we will review the difficulties to define a unique temperature out of equilibrium, the majority of definitions that have been proposed so far, and discuss both their advantages and limitations. We will then examine a variety of experimental techniques developed for measuring the non-equilibrium local temperatures under various conditions. Finally we will discuss the physical implications of the notion of local temperature, and present the practical applications of such a concept in a variety of nanosystems out of equilibrium. Figure 4: (a) The product of the density of states η(E) times the global distribution function ϕ|ρ|ϕ forms a strongly pronounced peak at the expectation value of the global system energyĒ. (b) The logarithm of the local distribution function a|ρ|a (solid line) and the logarithm of a canonical distribution (dashed line) with the same local temperature for a harmonic chain. (a) and (b) are reprinted with permission from [74].

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Section: Ectormentioning

confidence: 99%

Local temperatures out of equilibrium

2019

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“…Here we take the parameters t , which is corresponding to 2 6MHz a g p =´ [4]. As the coupling between an atom and reservoir 1 is quite weak, we only simulate the quantum controlled-PHASE gate under different g , 2 h , a t in ( ) or a t iñ ( )(equation (33)). The detailed numerical results are shown in figure 7 through 9.…”

Section: Lorentzian Reservoirmentioning

confidence: 99%

“…In these situations, the non-Markovian approximation involving the memory from the reservoirs should be introduced to study the dynamics of open quantum systems. Hence, the non-Markovian quantum dynamics is drawing increasing attention [28][29][30][31][32][33][34][35][36][37][38][39][40][41].Here, in a non-Markovian approach, we investigate the performance of a quantum controlled-PHASE gate constituted by an atom trapped in a single-sided cavity. Both the coupling between an atom and the environment and the interaction between the single cavity mode and a reservoir are taken into account.…”

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confidence: 99%

Deterministic quantum controlled-PHASE gates based on non-Markovian environments

2017

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We study the realization of the quantum controlled-PHASE gate in an atom-cavity system beyond the Markovian approximation. The general description of the dynamics for the atom-cavity system without any approximation is presented. When the spectral density of the reservoir has the Lorentz form, by making use of the memory backflow from the reservoir, we can always construct the deterministic quantum controlled-PHASE gate between a photon and an atom, no matter the atomcavity coupling strength is weak or strong. While, the phase shift in the output pulse hinders the implementation of quantum controlled-PHASE gates in the sub-Ohmic, Ohmic or super-Ohmic reservoirs.

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“…(see supplementary text section I for detail) TDDFT-NEGF had been used to simulate quasi-one-dimensional electronic device. Recently, we develop numerical scheme to obtain the self-energies for monolayer surface [28,29] and bulk materials [30], and simulate the transient electronic dynamics in quasi-twodimensional and three-dimensional systems. The interesting thing is that computational cost for bulk material is least due to the smooth density of states of the bulk material.…”

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confidence: 99%

Tracking the electronic oscillation in molecule with tunneling microscopy

Wang,

Bi,

et al. 2020

Preprint

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Visualizing and controlling electron dynamics over femtosecond timescale play a key role in the design of next-generation electronic device. Using simulations, we demonstrate the electronic oscillation inside naphthalene molecule can be tracked by means of the tuning of delay time between two identical femtosecond laser pulses. Both the frequency and decay time of the oscillation are detected by the tunneling charge through the junction of scanning tunneling microscopy. And the tunneling charge is sensitive to the carrier-envelope phase (CEP) for few-cycle long optical pulses. While this sensitivity to CEP will disappear with the increase of time-length of pulses. Our simulation results show that it is possible to visualize and control the electron dynamics inside molecule by one or two femtosecond laser pulses.

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Time-dependent density functional theory for open systems with a positivity-preserving decomposition scheme for environment spectral functions

Cited by 11 publications

References 44 publications

Local temperatures out of equilibrium

Local temperatures out of equilibrium

Deterministic quantum controlled-PHASE gates based on non-Markovian environments

Tracking the electronic oscillation in molecule with tunneling microscopy

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