DISSIPATIVE BLACKBODY RADIATION: RADIATION IN A LOSSY CAVITY

2004 ◽  
Vol 18 (03) ◽  
pp. 317-324 ◽  
Author(s):  
J. R. CHOI
Keyword(s):  
Energy Density ◽  
Density Operator ◽  
Invariant Operator ◽  
Blackbody Radiation ◽  
Von Neumann ◽  
The Media ◽  
Von Neumann Equation

We defined normalized density operator that satisfies Liouville–von Neumann equation in terms of the invariant operator. The energy density inside the cavity decreased exponentially with time due to the conductivity of the media. We also evaluated the total number of photons in the cavity.

Verallgemeinerte physikalische Entropien auf informationstheoretischer Grundlage

1965 ◽  
Vol 20 (12) ◽  
pp. 1543-1553 ◽  
Author(s):  
H. Schwegler
Keyword(s):  
Density Operator ◽  
Gibbs Equation ◽  
Macroscopic Equation ◽  
Von Neumann ◽  
Special Cases ◽  
Self Consistent ◽  
Von Neumann Equation ◽  
The Times ◽  
Experimental Values ◽  
Special Case

Physical entropies SB are defined with respect to a certain set of variables, the observationlevel B. For all times in which B exists, SB is the uncertainty H of a density operator RB making H a maximum with respect to the experimental values of B. This definition is not restricted to the thermodynamic equilibrium. The entropies SB measure the vagueness of the description in Hilbert-space caused by the choice of B. The time dependence of the density operator RB is not governed by the von Neumann equation, but in the special case of a “self-consistent“ B it may be calculated with the help of this equation. An increasing SB is obtained.If the times for which B exists are sufficiently close, a macroscopic equation for the time deriva· tive of SB is given. Three special cases of B are considered, leading to the Gibbs equation, a generalized entropy equation for heat conduction and an entropy equation for the multipole relaxation.

scholarly journals Phenomenological quantum thermodynamics resource theory for closed bipartite Schottky systems

2020 ◽  
Vol 378 (2170) ◽  
pp. 20190173 ◽  
Author(s):  
Wolfgang Muschik
Keyword(s):  
Quantum Mechanics ◽  
Density Operator ◽  
Nonequilibrium Thermodynamics ◽  
Discrete Systems ◽  
Resource Theory ◽  
Quantum Thermodynamics ◽  
Theme Issue ◽  
Von Neumann ◽  
Starting Point ◽  
Von Neumann Equation

How to introduce thermodynamics to quantum mechanics? From numerous possibilities of solving this task, the simple choice is here: the conventional von Neumann equation deals with a density operator whose probability weights are time-independent. Because there is no reason apart from the reversible quantum mechanics that these weights have to be time-independent, this constraint is waived, which allows one to introduce thermodynamical concepts to quantum mechanics. This procedure is similar to that of Lindblad’s equation, but different in principle. But beyond this simple starting point, the applied thermodynamical concepts of discrete systems may perform a ‘source theory’ for other versions of phenomenological quantum thermodynamics. This article is part of the theme issue ‘Fundamental aspects of nonequilibrium thermodynamics’.

scholarly journals ENTANGLEMENT DYNAMICS IN FINITE QUDIT CHAIN IN CONSISTENT MAGNETIC FIELD

2012 ◽  
Vol 10 (06) ◽  
pp. 1250068 ◽  
Author(s):  
E. A. IVANCHENKO
Keyword(s):  
Magnetic Field ◽  
Entanglement Dynamics ◽  
Von Neumann ◽  
Magnetic Field Modulation ◽  
Entanglement Measures ◽  
Analytical Formulae ◽  
Initial States ◽  
Von Neumann Equation ◽  
Field Modulation ◽  
The Magnetic Field

Based on the Liouville–von Neumann equation, we obtain a closed system of equations for the description of a qutrit or coupled qutrits in an arbitrary, time-dependent, external magnetic field. The dependence of the dynamics on the initial states and the magnetic field modulation is studied analytically and numerically. We compare the relative entanglement measure's dynamics in bi-qudits with permutation particle symmetry. We find the magnetic field modulation which retains the entanglement in the system of two coupled qutrits. Analytical formulae for the entanglement measures in finite chains from two to six qutrits or three quartits are presented.

scholarly journals Concepts of Phenomenological Irreversible Quantum Thermodynamics I: Closed Undecomposed Schottky Systems in Semi-Classical Description

2019 ◽  
Vol 44 (1) ◽  
pp. 1-13 ◽  
Author(s):  
Wolfgang Muschik
Keyword(s):  
Time Dependent ◽  
Quantum Thermodynamics ◽  
Time Rate ◽  
Von Neumann ◽  
Classical Description ◽  
Von Neumann Equation

Abstract If the von Neumann equation is modified by time dependent statistical weights, the time rate of entropy, the entropy exchange and the production of a Schottky system are derived whose Hamiltonian does not contain the interaction with the system’s environment. This interaction is semi-classically described by the quantum theoretical expressions of power and entropy exchange.

IS SEISMIC ENERGY OF DIAGNOSTIC VALUE?

Geophysics ◽  
1969 ◽  
Vol 34 (2) ◽  
pp. 196-212 ◽  
Author(s):  
A. J. Hermont
Keyword(s):  
Energy Density ◽  
Particle Velocity ◽  
Measurement Errors ◽  
Attenuation Factor ◽  
Seismic Energy ◽  
Diagnostic Value ◽  
Reflection Data ◽  
The Media ◽  
Factor Data ◽  
Spatial Attenuation

Since both the intensity of a seismic wave and its energy density are directly related to the square of the particle velocity, a quantity available as the output of a geophone, it is feasible to record energy density as a function of time and space. The energy recorded is a function of the spatial attenuation factors of the media traversed, the partition at reflection boundaries, and the geometric spreading. If a proper correction can be made for the latter two effects, it is possible to generate a function that is diagnostic of the attenuation properties of the geologic model and may be useful for lithologic interpretation. A quantity that is proportional to the logarithm of the peak absolute value of the square of the particle velocity, or the logarithm of the energy density, was recorded along a series of test profiles. Conventional reflection data were also recorded. The purpose of the field program was to gain preliminary experience in energy recording and to seek an answer to the query posed in the title. The main conclusion is affirmative. This, however, must be qualified. It is apparent that several serious impediments must be overcome. It is necessary to develop satisfactory techniques to remove the geometric and reflectivity effects from the recorded energy data, to eliminate measurement errors which can produce magnitude errors of several orders, and, above all, to develop a detailed and accurate set of in‐situ spatial attenuation factor data.

scholarly journals PARAMETRIC DOWN CONVERSION OF A BOSONIC THERMOFIELD VACUUM

2012 ◽  
Vol 27 (22) ◽  
pp. 1250124 ◽  
Author(s):  
THIAGO PRUDÊNCIO
Keyword(s):  
Input State ◽  
Von Neumann ◽  
Vacuum States ◽  
Parametric Down Conversion ◽  
Von Neumann Equation ◽  
Down Conversion

We consider a process of parametric down conversion where the input state is a bosonic thermofield vacuum. This state leads to a parametric down conversion, generating an output of two excited photons. Following a thermofield dynamics scheme, the input state, initially in a bosonic thermofield vacuum, and the output states, initially in vacuum states, evolve under a Liouville–von Neumann equation.

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