scholarly journals Thermodynamics of quantum Brownian motion with internal degrees of freedom: the role of entanglement in the strong-coupling quantum regime

2005 ◽  
Vol 38 (33) ◽  
pp. 7325-7340 ◽  
Author(s):  
C Hörhammer ◽  
H Büttner
Keyword(s):  
Brownian Motion ◽  
Strong Coupling ◽  
Degrees Of Freedom ◽  
Quantum Brownian Motion ◽  
Quantum Regime ◽  
Internal Degrees Of Freedom

Role of internal degrees of freedom in laser-light coherence

1993 ◽  
Vol 47 (2) ◽  
pp. 1274-1277 ◽  
Author(s):  
A. M. Khazanov ◽  
G. A. Koganov ◽  
R. Shuker
Keyword(s):  
Degrees Of Freedom ◽  
Laser Light ◽  
Internal Degrees Of Freedom

UNIFIED ELECTROWEAK MODEL BASED ON SPACE–TIME AND ISOSPIN SYMMETRIES

2005 ◽  
Vol 20 (01) ◽  
pp. 175-198 ◽  
Author(s):  
D. SPEHLER ◽  
G. C. MARQUES
Keyword(s):  
Degrees Of Freedom ◽  
Space Time ◽  
Scalar Particles ◽  
Symmetry Breakdown ◽  
Vector Bosons ◽  
Rank 2 ◽  
Electroweak Model ◽  
Spontaneous Symmetry Breakdown ◽  
Internal Degrees Of Freedom

We propose a spinorial approach to the unified electroweak interactions, in which no use is made of spontaneous symmetry breakdown. No scalar particles are needed in order to break the symmetry. No reference is made to gauge symmetry. Our approach stresses the role of space–time and isospin symmetries in the build up of the electroweak model. Internal degrees of freedom, such as isospin, are incorporated in the theory by using spinors carrying isospin indices. All vector bosons are described by a rank 2 field in the spinorial and the isospinorial indices. Leptons are accomodated in a rank 1 spinor field and in a rank 2 isospin field as well. The dynamical variables of the theory are the chiral and isochiral components of these fields.

Vapor Pressure and Sublimation Rate of Molecular Crystals:  Role of Internal Degrees of Freedom

2007 ◽  
Vol 111 (51) ◽  
pp. 14290-14294 ◽  
Author(s):  
A. Maiti ◽  
L. A. Zepeda-Ruiz ◽  
R. H. Gee ◽  
A. K. Burnham
Keyword(s):  
Vapor Pressure ◽  
Degrees Of Freedom ◽  
Molecular Crystals ◽  
Sublimation Rate ◽  
Internal Degrees Of Freedom

scholarly journals Bose polaron as an instance of quantum Brownian motion

Quantum ◽  
2017 ◽  
Vol 1 ◽  
pp. 30 ◽  
Author(s):  
Aniello Lampo ◽  
Soon Hoe Lim ◽  
Miguel Ángel García-March ◽  
Maciej Lewenstein
Keyword(s):  
Brownian Motion ◽  
Langevin Equation ◽  
Degrees Of Freedom ◽  
Interaction Strength ◽  
Einstein Condensate ◽  
Generalized Langevin Equation ◽  
Quantum Gas ◽  
Quantum Brownian Motion ◽  
Bose Einstein Condensate ◽  
Bose Einstein

We study the dynamics of a quantum impurity immersed in a Bose-Einstein condensate as an open quantum system in the framework of the quantum Brownian motion model. We derive a generalized Langevin equation for the position of the impurity. The Langevin equation is an integrodifferential equation that contains a memory kernel and is driven by a colored noise. These result from considering the environment as given by the degrees of freedom of the quantum gas, and thus depend on its parameters, e.g. interaction strength between the bosons, temperature, etc. We study the role of the memory on the dynamics of the impurity. When the impurity is untrapped, we find that it exhibits a super-diffusive behavior at long times. We find that back-flow in energy between the environment and the impurity occurs during evolution. When the particle is trapped, we calculate the variance of the position and momentum to determine how they compare with the Heisenberg limit. One important result of this paper is that we find position squeezing for the trapped impurity at long times. We determine the regime of validity of our model and the parameters in which these effects can be observed in realistic experiments.

scholarly journals Computer simulations of Brownian motion of complex systems

1995 ◽  
Vol 282 ◽  
pp. 373-403 ◽  
Author(s):  
P. S. Grassia ◽  
E. J. Hinch ◽  
L. C. Nitsche
Keyword(s):  
Brownian Motion ◽  
Complex Systems ◽  
Computer Simulations ◽  
Degrees Of Freedom ◽  
Two Dimensions ◽  
Polymer Molecule ◽  
One Dimension ◽  
Macromolecular Systems ◽  
Internal Degrees Of Freedom

Care is needed with algorithms for computer simulations of the Brownian motion of complex systems, such as colloidal and macromolecular systems which have internal degrees of freedom describing changes in configuration. Problems can arise when the diffusivity or the inertia changes with the configuration of the system. There are some problems in replacing very stiff bonds by rigid constraints. These problems and their resolution are illustrated by some artificial models; firstly in one dimension, then in the neighbourhood of an ellipse in two dimensions and finally for the trimer polymer molecule.

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