A density-matrix approach to thermal equilibrium states

1987 ◽  
Vol 326 (2) ◽  
pp. 179-184
Author(s):  
S. Peltier
Keyword(s):  
Density Matrix ◽  
Thermal Equilibrium ◽  
Equilibrium States ◽  
Matrix Approach ◽  
Approach To Thermal Equilibrium

Few-Particle Effects in Nonlinear Optical Spectra of Semiconductor Quantum Dots

1999 ◽  
Vol 571 ◽  
Author(s):  
Ulrich Hohenesteri ◽  
Fausto Rossi ◽  
Elisa Molinari
Keyword(s):  
Quantum Dots ◽  
Density Matrix ◽  
Nonlinear Optical ◽  
Coherent Control ◽  
Optical Spectra ◽  
Carrier Dynamics ◽  
Semiconductor Quantum Dots ◽  
Nonequilibrium Carrier ◽  
Optical Nonlinearities ◽  
Matrix Approach

ABSTRACTWe present a density-matrix approach for the description of nonequilibrium carrier dynamics in optically excited semiconductor quantum dots, that explicitly accounts for exciton-exciton as well as exciton-carrier interactions. Within this framework, we analyze few-particle effects in the optical spectra and provide a consistent description of additional peaks appearing at high photoexcitation density. We discuss possible applications of such optical nonlinearities in future coherent-control experiments.

Optical properties of Quantum Disks: Real density matrix approach

Open Physics ◽  
2006 ◽  
Vol 4 (2) ◽  
Author(s):  
Gerard Czajkowski ◽  
Leonardo Silvestri
Keyword(s):  
Density Matrix ◽  
Guided Wave ◽  
Matrix Approach ◽  
Electron Hole ◽  
Optical Functions ◽  
Quantum Disk ◽  
All Optical ◽  
Quantum Disks ◽  
Analytical Expressions ◽  
Real Density

AbstractWe show how to compute the optical response of a Quantum Disk (QDisk) to an electromagnetic wave as a function of the incident wave polarization, in the energetic region of interband transitions. Both the TM and TE polarization in guided-wave geometry are analyzed. The method uses the microscopic calculation of Quantum Disk eigenfunctions and the macroscopic real density matrix approach to compute the effective QDisk susceptibility, taking into account the valence band structure of the QDisk material and the Coulomb interaction between the electron and the hole. Analytical expressions for the QDisk susceptibility are obtained for a certain model electron — hole potential. Using these expressions, all optical functions can be computed. Results for the absorption coefficient are computed for InAs/GaAs QDisks. Fair agreement with experiments is obtained.

LINEAR AND NONLINEAR INTERSUBBAND REFRACTIVE INDEX CHANGES IN WURTZITEAlGaN/GaNDOUBLE QUANTUM WELLS: EFFECTS OF PIEZOELECTRICITY AND SPONTANEOUS POLARIZATION

2009 ◽  
Vol 16 (01) ◽  
pp. 11-17
Author(s):  
L. ZHANG
Keyword(s):  
Refractive Index ◽  
Density Matrix ◽  
Quantum Wells ◽  
Structural Parameters ◽  
Matrix Approach ◽  
Third Order ◽  
Numerical Result ◽  
Analytical Formulas ◽  
Index Changes ◽  
Linear And Nonlinear

Based on the density-matrix approach and iterative treatment, a detailed procedure for the calculation of the linear and nonlinear intersubband refractive index changes (RICs) in wurtzite GaN-based coupling quantum wells (CQWs) is given. The simple analytical formulas for electronic eigenstates and the linear and third-order nonlinear RICs in the systems are also deduced. Numerical result on a typical AlGaN / GaN CQW shows that the linear and nonlinear RICs sensitively depend on the structural parameters of the CQW system as well as the doped fraction of nitride semicondutor.

Quantum statistical physics: Functional integration formalism

2021 ◽  
pp. 64-89
Author(s):  
Jean Zinn-Justin
Keyword(s):  
Phase Space ◽  
Integral Representation ◽  
Density Matrix ◽  
Thermal Equilibrium ◽  
Degrees Of Freedom ◽  
Functional Integral ◽  
Complex Variables ◽  
Path Integral Representation ◽  
Canonical Formulation ◽  
Grand Canonical

The functional integral representation of the density matrix at thermal equilibrium in non-relativistic quantum mechanics (QM) with many degrees of freedom, in the grand canonical formulation is introduced. In QM, Hamiltonians H(p,q) can be also expressed in terms of creation and annihilation operators, a method adapted to the study of perturbed harmonic oscillators. In the holomorphic formalism, quantum operators act by multiplication and differentiation on a vector space of analytic functions. Alternatively, they can also be represented by kernels, functions of complex variables that correspond in the classical limit to a complex parametrization of phase space. The formalism is adapted to the description of many-body boson systems. To this formalism corresponds a path integral representation of the density matrix at thermal equilibrium, where paths belong to complex spaces, instead of the more usual position–momentum phase space. A parallel formalism can be set up to describe systems with many fermion degrees of freedom, with Grassmann variables replacing complex variables. Both formalisms can be generalized to quantum gases of Bose and Fermi particles in the grand canonical formulation. Field integral representations of the corresponding quantum partition functions are derived.

Density-matrix approach to nonequilibrium free-carrier screening in semiconductors

1997 ◽  
Vol 56 (20) ◽  
pp. 13177-13189 ◽  
Author(s):  
U. Hohenester ◽  
W. Pötz
Keyword(s):  
Density Matrix ◽  
Carrier Screening ◽  
Free Carrier ◽  
Matrix Approach

A density matrix approach to the Goldanskii-Karyagin effect

1989 ◽  
Vol 160 (3) ◽  
pp. 393-399 ◽  
Author(s):  
K. Ruebenbauer ◽  
B. Miczko ◽  
T. Birchall
Keyword(s):  
Density Matrix ◽  
Matrix Approach
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