Related Experiment Video
Updated: Jul 31, 2026
10:00
Gradient Echo Quantum Memory in Warm Atomic Vapor
Published on: November 11, 2013
Memory effects and nonequilibrium transport in open many-particle quantum systems
Irena Knezevic1, David K Ferry
1Department of Electrical Engineering and Center for Solid State Electronics Research, Arizona State University, Tempe, Arizona 85287-6206, USA. irenak@asu.edu
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|October 26, 2005
Summary
Treating mesoscopic systems as open is crucial for understanding relaxation and transport. This study generalizes nonequilibrium Green's function formalism to open systems, revealing distinct memory and entanglement effects in transient transport.
Area of Science:
- Condensed matter physics
- Quantum transport phenomena
- Many-body theory
Background:
- Understanding relaxation mechanisms and far-from-equilibrium transport in mesoscopic structures is essential.
- Current formalisms often treat systems as closed, neglecting environmental interactions.
- Mesoscopic systems are inherently open and coupled to their environment.
Purpose of the Study:
- Generalize the Kadanoff-Baym-Keldysh nonequilibrium Green's function formalism for open systems.
- Analyze the influence of memory effects and initial environment state on open-system transport.
- Derive accurate transport equations for transient and steady-state regimes in open mesoscopic systems.
Main Methods:
- Generalization of Kadanoff-Baym-Keldysh formalism to open systems.
- Definition and analysis of two-time correlation functions.
- Derivation of transport equations accounting for system-environment coupling.
Main Results:
- Two-time correlation functions in the transient regime exhibit distinct closed-system, entanglement, and memory terms.
- Environmental influence cannot be eliminated by initial state choice; closed-system approximation is invalid for significant coupling.
- In far-from-equilibrium steady states, correlation functions regain a closed-system-like form with modified Hamiltonians.
Conclusions:
- The transient and steady-state regimes differ in the relative importance of entanglement and memory terms.
- Accurate theoretical investigation of nonequilibrium quasiparticle transport requires distinguishing these regimes.
- Environmental coupling significantly impacts transport, necessitating open-system treatments.
Related Concept Videos
02:39Emission Spectra
When solids, liquids, or condensed gases are heated sufficiently, they radiate some of the excess energy as light. Photons produced in this manner have a range of energies, and thereby produce a continuous spectrum in which an unbroken series of wavelengths is present.
02:32The de Broglie Wavelength
In the macroscopic world, objects that are large enough to be seen by the naked eye follow the rules of classical physics. A billiard ball moving on a table will behave like a particle; it will continue traveling in a straight line unless it collides with another ball, or it is acted on by some other force, such as friction. The ball has a well-defined position and velocity or well-defined momentum, p = mv, which is defined by mass m and velocity v at any given moment. This is the typical...
01:10First Law: Particles in One-dimensional Equilibrium
Newton's first law of motion states that a body at rest remains at rest, or if in motion, remains in motion at constant velocity, unless acted on by a net external force. It also states that there must be a cause for any change in velocity (a change in either magnitude or direction) to occur. This cause is a net external force. For example, consider what happens to an object sliding along a rough horizontal surface. The object quickly grinds to a halt, due to the net force of friction. If we...
01:23Equilibrium Conditions for a Particle
When an object is in equilibrium, it is either at rest or moving with a constant velocity. There are two types of equilibrium: static and dynamic. Static equilibrium occurs when an object is at rest, while dynamic equilibrium occurs when an object is moving with a constant velocity. In both cases, there must be a balance of forces acting on the object.
To understand the concept of equilibrium, let us first consider the forces acting on an object. When different forces act on an object, they can...
To understand the concept of equilibrium, let us first consider the forces acting on an object. When different forces act on an object, they can...
01:22Carrier Generation and Recombination
Carrier generation is the process by which electron-hole pairs (EHPs) are created within the semiconductor. In direct-bandgap semiconductors, such as gallium arsenide (GaAs), this occurs efficiently when energy absorption prompts valence electrons to leap into the conduction band, leaving behind holes.
This process is given by the generation rate G and is efficient due to the conservation of momentum between the valence band maximum and conduction band minimum.
Indirect generation involves an...
This process is given by the generation rate G and is efficient due to the conservation of momentum between the valence band maximum and conduction band minimum.
Indirect generation involves an...
01:21Carrier Transport
The generation of electrical current in semiconductors is fundamentally driven by two mechanisms: drift and diffusion. These processes are essential for the functionality and performance of semiconductor-based devices.
Drift Current:
The drift of charge carriers is started by an external electric field (E). Charged particles, such as electrons and holes, experience an acceleration between collisions with lattice atoms. For electrons, this results in a drift velocity (vd) given by:
Drift Current:
The drift of charge carriers is started by an external electric field (E). Charged particles, such as electrons and holes, experience an acceleration between collisions with lattice atoms. For electrons, this results in a drift velocity (vd) given by: