Physics – Condensed Matter – Statistical Mechanics
Scientific paper
2009-07-09
Phys. Rev. E 81, 031131 (2010)
Physics
Condensed Matter
Statistical Mechanics
34pages, no figure
Scientific paper
Relation among various expressions of the complex admittance for quantum systems in contact with heat reservoir is studied. Exact expressions of the complex admittance are derived in various types of formulations of equations of motion under contact with heat reservoir. Namely, the complex admittance is studied in the relaxation method and the external-field method. In the former method, the admittance is calculated using the Kubo formula for quantum systems in contact with heat reservoir in no external driving fields, while in the latter method the admittance is directly calculated from equations of motion with external driving terms. In each method, two types of equation of motions are considered, i.e., the time-convolution (TC) equation and time-convolutionless (TCL) equation. That is, the full of the four cases are studied. It is turned out that the expression of the complex admittance obtained by using the relaxation method with the TC equation exactly coincides with that obtained by using the external-field method with the TC equation, while other two methods give different forms. It is also explicitly demonstrated that all the expressions of the complex admittance coincide with each other in the lowest Born approximation for the systemreservoir interaction. The formulae necessary for the higher order expansions in powers of the system-reservoir interaction are derived, and also the expressions of the admittance in the n-th order approximation are given. To characterize the TC and TCL methods, we study the expressions of the admittances of two exactly solvable models. Each exact form of admittance is compared with the results of the two methods in the lowest Born approximation. It is found that depending on the model, either of TC and TCL would be the better method.
Miyashita Seiji
Mori Takashi
Saeki Mizuhiko
Uchiyama Chikako
No associations
LandOfFree
Comparison among Various Expressions of Complex Admittance for Quantum System in Contact with Heat Reservoir does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Comparison among Various Expressions of Complex Admittance for Quantum System in Contact with Heat Reservoir, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Comparison among Various Expressions of Complex Admittance for Quantum System in Contact with Heat Reservoir will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-341618