Time-dependent quantum transport: Direct analysis in the time domain

Zhu, Yu; Maciejko, Joseph; Tao, Jing; Guo, Hong; Wang, Jian

doi:10.1103/physrevb.71.075317

Cited by 108 publications

(119 citation statements)

References 42 publications

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“…First we calculate the isolated Green's function of the central system and selfenergy with different Keldysh components in the time domain. 50 For the quantum dot with single energy level…”

Section: Appendix A: Fermionic Coherent Statesmentioning

confidence: 99%

Full-counting statistics of charge and spin transport in the transient regime: A nonequilibrium Green's function approach

Tang

Wang

2014

Phys. Rev. B

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We report the investigation of full-counting statistics (FCS) of transferred charge and spin in the transient regime where the connection between central scattering region (quantum dot) and leads are turned on at t = 0. A general theoretical formulation for the generating function (GF) is presented using a nonequilibrium Green's function approach for the quantum dot system. In particular, we give a detailed derivation on how to use the method of path integral together with nonequilibrium Green's function technique to obtain the GF of FCS in electron transport systems based on the two-time quantum measurement scheme. The correct long-time limit of the formalism, the Levitov-Lesovik's formula, is obtained. This formalism can be generalized to account for spin transport for the system with noncollinear spin as well as spin-orbit interaction. As an example, we have calculated the GF of spin-polarized transferred charge, transferred spin, as well as the spin transferred torque for a magnetic tunneling junction in the transient regime. The GF is compactly expressed by a functional determinant represented by Green's function and self-energy in the time domain. With this formalism, FCS in spintronics in the transient regime can be studied. We also extend this formalism to the quantum point contact system. For numerical results, we calculate the GF and various cumulants of a double quantum dot system connected by two leads in transient regime. The signature of universal oscillation of FCS is identified. On top of the global oscillation, local oscillations are found in various cumulants as a result of the Rabi oscillation. Finally, the influence of the temperature is also examined.

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“…First we calculate the isolated Green's function of the central system and selfenergy with different Keldysh components in the time domain. 50 For the quantum dot with single energy level…”

Section: Appendix A: Fermionic Coherent Statesmentioning

confidence: 99%

Full-counting statistics of charge and spin transport in the transient regime: A nonequilibrium Green's function approach

Tang

Wang

2014

Phys. Rev. B

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“…Combining these two concepts of time-periodic modulations and environment (bath) engineering, here we study the dynamics of open quantum systems where the environment thermodynamic parameters are periodically modulated. Even though there exists formally exact methods of treating such set-ups [45][46][47][48][49][50][51][52][53], they are generally quite difficult to use, bein computationally demanding. To simplify calculations, often the adiabatic approximation is used [54][55][56].…”

Section: A Introductionmentioning

confidence: 99%

Quantum transport under ac drive from the leads: A Redfield quantum master equation approach

Purkayastha

2017

Phys. Rev. B

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Evaluating the time-dependent dynamics of driven open quantum systems is relevant for a theoretical description of many systems, including molecular junctions, quantum dots, cavity-QED experiments, cold atoms experiments and more. Here, we formulate a rigorous microscopic theory of an out-of-equilibrium open quantum system of non-interacting particles on a lattice weakly coupled bilinearly to multiple baths and driven by periodically varying thermodynamic parameters like temperature and chemical potential of the bath. The particles can be either bosonic or fermionic and the lattice can be of any dimension and geometry. Based on Redfield quantum master equation under Born-Markov approximation, we derive a linear differential equation for equal time two-point correlation matrix, sometimes also called single-particle density matrix, from which various physical observables, for example, current, can be calculated. Various interesting physical effects, such as resonance, can be directly read-off from the equations. Thus, our theory is quite general gives quite transparent and easy-to-calculate results. We validate our theory by comparing with exact numerical simulations. We apply our method to a generic open quantum system, namely a double-quantum dot coupled to leads with modulating chemical potentials. Two most important experimentally relevant insights from this are : (i) time-dependent measurements of current for symmetric oscillating voltages (with zero instantaneous voltage bias) can point to the degree of asymmetry in the system-bath coupling, and (ii) under certain conditions, time-dependent currents can exceed time-averaged currents by several orders of magnitude, and can therefore be detected even when the average current is below the measurement threshold. A. IntroductionThe dynamics of a quantum system coupled to an external environment (so-called "open" quantum system) are a result of the intricate interplay between the coherent evolution of the quantum degrees of freedom, the structure of the environment and the form and strength of the system-environment coupling. From quantum cavities [1-3] and superconducting qubits [4][5][6][7][8][9] , through quantum dots [10][11][12][13][14][15], molecular junctions [16][17][18][19][20][21][22][23][24][25][26][27] and cold atoms [28][29][30][31] , to excitons traveling in photosynthetic complexes [32][33][34][35], open quantum systems show dynamics which can be far richer and more surprising than their coherent (environment-free) counterparts.Recent ideas of designing a quantum state by engineering a specific environment [36][37][38][39][40][41][42] or by a periodic modulation of the open system's Hamiltonian [16,43,44] open a path to new forms of control over quantum systems. Combining these two concepts of time-periodic modulations and environment (bath) engineering, here we study the dynamics of open quantum systems where the environment thermodynamic parameters are periodically modulated. Even though there exists formally exact methods of treating such set-ups...

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“…For the time dependent quantum transport, the theories are more complicated and the calculation for large systems still meets much challenge [8][9]. Some of the methods focus on the wavefunction propagation [10] and some others focus on the density matrix evolution with the lead spectrum approximation [9] or some time decomposition scheme [11][12].…”

Section: Introductionmentioning

confidence: 99%

Complex absorbing potential based Lorentzian fitting scheme and time dependent quantum transport

Xie

Kwok

Jiang

et al. 2014

The Journal of Chemical Physics

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Based on the complex absorbing potential (CAP) method, a Lorentzian expansion scheme is developed to express the self-energy. The CAP-based Lorentzian expansion of self-energy is employed to solve efficiently the Liouville-von Neumann equation of one-electron density matrix. The resulting method is applicable for both tight-binding and first-principles models, and is used to simulate the transient currents through graphene nanoribbons and a benzene molecule sandwiched between two carbon-atom-chains.

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Time-dependent quantum transport: Direct analysis in the time domain

Cited by 108 publications

References 42 publications

Full-counting statistics of charge and spin transport in the transient regime: A nonequilibrium Green's function approach

Full-counting statistics of charge and spin transport in the transient regime: A nonequilibrium Green's function approach

Quantum transport under ac drive from the leads: A Redfield quantum master equation approach

Complex absorbing potential based Lorentzian fitting scheme and time dependent quantum transport

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