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Related Experiment Video

Updated: Jun 22, 2026

Scalable Quantum Integrated Circuits on Superconducting Two-Dimensional Electron Gas Platform

Scalable Quantum Integrated Circuits on Superconducting Two-Dimensional Electron Gas Platform

Published on: August 2, 2019

Two-time quantum transport and quantum diffusion.

¹Paul-Drude-Intitut für Festkörperelektronik, Hausvogteiplatz 5-7, 10117 Berlin, Germany. kl@pdi-berlin.de

Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics

|June 13, 2009

Summary

A unified theory using the nonequilibrium Green's function technique explains quantum transport and diffusion in semiconductors. This microscopic approach reveals robust double-time transport effects, including a novel phononless steady-state current.

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Area of Science:

Condensed Matter Physics
Quantum Mechanics
Semiconductor Physics

Background:

Quantum transport and diffusion in semiconductors are typically studied using separate models.
Existing semiphenomenological studies lack a firm microscopic foundation.
General applicability to diverse quantum transport problems is limited.

Purpose of the Study:

To develop a unified microscopic theory for quantum transport and quantum diffusion in bulk semiconductors.
To provide a rigorous theoretical framework applicable to both extended and localized states.
To investigate quantum kinetics with emphasis on their double-time nature.

Main Methods:

Utilizing the nonequilibrium Green's function (NEGF) technique.
Developing a unified theoretical approach for quantum transport and diffusion.
Analyzing systems where the Hamiltonian does not commute with the dipole operator.

Main Results:

A unified theory is established for quantum transport and diffusion on equal footing.
The theory is applicable to transport via extended and localized states.
All quasimomenta of the carrier distribution function are shown to be present and functional in homogeneous systems.
A novel phononless steady-state current is identified, demonstrating robust double-time transport effects.

Conclusions:

The developed NEGF approach provides a microscopic basis for understanding quantum transport and diffusion.
The theory offers a general framework applicable to a wide range of quantum transport phenomena.
The identified phononless current highlights the significance of the double-time nature of quantum kinetics in semiconductor transport.