Quantum interference and the time-dependent radiation of nanojunctions

Ridley, Michael; Kantorovich, Lev; Leeuwen, Robert van; Tuovinen, Riku

doi:10.1103/physrevb.103.115439

Cited by 14 publications

(13 citation statements)

References 91 publications

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“…• It does not contradict the thermodynamic arrow of time: the forwards and backwards oriented parts of the wave function combine to produce observed reality. Indeed, directional processes such as dissipation and relaxation to nonequilibrium steady states in open quantum systems are described by Keldysh-based methods on a routine basis [44,[54][55][56].…”

Section: Discussionmentioning

confidence: 99%

Quantum probability from causal structure

Ridley¹

2021

Preprint

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The Born probability measure describes the statistics of measurements in which observers selflocate themselves in some region of reality. In ψ-ontic quantum theories, reality is directly represented by the wavefunction. We show that quantum probabilities may be identified with fractions of a universal multiple-time wavefunction containing both causal and retrocausal temporal parts. This wavefunction is defined in an appropriately generalized history space on the Keldysh time contour. Our deterministic formulation of quantum mechanics replaces the initial condition of standard Schrödinger dynamics with a network of 'fixed points' defining quantum histories on the contour. The Born measure is derived by summing up the wavefunction along these histories. We then apply the same technique to the derivation of the statistics of measurements with pre-and post-selection.

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Section: Discussionmentioning

confidence: 99%

Quantum probability from causal structure

Ridley¹

2021

Preprint

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“…Recent progress in this issue has allowed for an equivalent but more efficient representation of the GKBA time evolution with only a linear scaling in the number of time steps [74][75][76][77]. It would be very useful to extend these procedures to open quantum systems in order to study, e.g., time-dependent radiation in molecular junctions out-of-equilibrium [78,79]. This shall be addressed in a forthcoming paper.…”

Section: Discussionmentioning

confidence: 99%

Electron correlation effects in superconducting nanowires in and out of equilibrium

Tuovinen

2021

Preprint

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One-dimensional nanowires with strong spin-orbit coupling and proximity-induced superconductivity are predicted to exhibit topological superconductivity with condensed-matter analogues to Majorana fermions. Here, the nonequilibrium Green's function approach with the generalized Kadanoff-Baym ansatz is employed to study the electron-correlation effects and their role in the topological superconducting phase in and out of equilibrium. Electron-correlation effects are found to affect the transient signatures regarding the zero-energy Majorana states, when the superconducting nanowire is subjected to external perturbations such as magnetic-field quenching, laser-pulse excitation, and coupling to biased normal-metal leads.

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“…( 2). Finally, at the same instant of time in which ρ ij (t) and M ij (t) are self-consistently computed, we also compute bond [49,55,60] charge…”

Section: B Quantum Dynamics Of Electrons With Dissipation and Decoher...mentioning

confidence: 99%

“…The pulse and/or the dynamics of LMMs generate interlayer (I Mn 3 Sn→Pt and I Sα Mn 3 Sn→Pt ) and intralayer (I Pt and I Sα Pt ) charge (I) and spin (I Sα ) currents. The time-dependent charge currents and densities determine, via the Jefimenko equations [48,49], emitted THz radiation illustrated on the right, as well as high harmonics of the center frequency Ω0 of the laser pulse in the emitted EM radiation.…”

Section: Introductionmentioning

confidence: 99%

“…In this study, we develop a multiscale quantumclassical approach [Fig. 2] where: quantum transport of electrons, including dissipation and decoherence effects due to coupling to an external bosonic bath, is described by QME [42] of the Lindblad type [63,64] for electronic nonequilibrium one-particle density matrix; dynamics of classical LMMs is described via the LLG equation within the general framework of atomistic spin dynamics [35,36]; and incoming light is described by classical vector potential, which couples to electrons in QME, while properly retarded electric and magnetic fields of emitted EM radiation are computed from the Jefimenko equations [48] adapted [49] to use time-dependent bond charge currents [49,60] and charge densities as field sources extracted from QME-based quantum transport treatment of electrons. We apply these QME+LLG (for equilibration) and QME+LLG+Jefimenko (for laser pulse driven nonequilibrium dynamics and emitted EM radiation) calculations to a bilayer [Fig.…”

Section: Introductionmentioning

confidence: 99%

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Quantum-classical approach to spin and charge pumping and the ensuing radiation in THz spintronics with example of ultrafast-light-driven Weyl antiferromagnet Mn$_3$Sn

Suresh¹,

Nikolić²

2022

Preprint

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The interaction of fs laser pulse with magnetic materials has been intensely studied for more than two decades in order to understand ultrafast demagnetization in single magnetic layers or THz emission from their bilayers with nonmagnetic spin-orbit (SO) materials. However, in contrast to wellunderstood spin and charge pumping by dynamical magnetization in spintronic systems driven by microwaves or current injection, analogous processes in light-driven magnets and radiation emitted by them remain largely unexplained due to multiscale nature of the problem. Here we develop a multiscale quantum-classical formalism-where conduction electrons are described by quantum master equation of the Lindblad type; classical dynamics of local magnetization is described by the Landau-Lifshitz-Gilbert (LLG) equation; and incoming light is described by classical vector potential while outgoing electromagnetic radiation is computed using Jefimenko equations for retarded electric and magnetic fields-and apply it to a bilayer of antiferromagnetic Weyl semimetal Mn3Sn, hosting noncollinear local magnetization, and SO-coupled nonmagnetic material. Our QME+LLG+Jefimenko scheme makes it possible to understand how fs laser pulse generates directly spin and charge pumping and electromagnetic radiation by the latter, including both odd and even high harmonics (of the pulse center frequency) up to order n ≤ 7. The directly pumped spin current then exert spin torque on local magnetization whose dynamics, in turn, pumps additional spin and charge currents radiating in the THz range. By switching on and off LLG dynamics and SO couplings, we unravel which microscopic mechanism contribute the most to emitted THz radiation-charge pumping by local magnetization of Mn3Sn in the presence of its own SO coupling is far more important than standardly assumed (for other types of magnetic layers) spin pumping and subsequent spin-to-charge conversion within the neighboring nonmagnetic SO-coupled material.

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Quantum interference and the time-dependent radiation of nanojunctions

Cited by 14 publications

References 91 publications

Quantum probability from causal structure

Quantum probability from causal structure

Electron correlation effects in superconducting nanowires in and out of equilibrium

Quantum-classical approach to spin and charge pumping and the ensuing radiation in THz spintronics with example of ultrafast-light-driven Weyl antiferromagnet Mn$_3$Sn

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