Transient Dynamics of Double Quantum Dots Coupled to Two Reservoirs

We study the time-dependent properties of double quantum dots coupled to two reservoirs using the nonequilibrium Green function method. For an arbitrary time-dependent bias, we derive an expression for the time-dependent electron density of a dot and several currents, including the current between t...

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Bibliographic Details
Published in:Journal of the Physical Society of Japan 2018-05, Vol.87 (5), p.54006
Main Authors: Fukadai, Takahisa, Sasamoto, Tomohiro
Format: Article
Language:English
Subjects:
Approximation
Bias
Coupling
Electron density
Green's functions
Quantum dots
Quantum theory
Relaxation time
Reservoirs
Time dependence
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Summary:We study the time-dependent properties of double quantum dots coupled to two reservoirs using the nonequilibrium Green function method. For an arbitrary time-dependent bias, we derive an expression for the time-dependent electron density of a dot and several currents, including the current between the dots in the wide-band-limit approximation. For the special case of a constant bias, we calculate the electron density and the currents numerically. As a result, we find that these quantities oscillate and that the number of crests in a single period of the current from a dot changes with the bias voltage. We also obtain an analytical expression for the relaxation time, which expresses how fast the system converges to its steady state. From the expression, we find that the relaxation time becomes constant when the coupling strength between the dots is sufficiently large in comparison with the difference of coupling strength between the dots and the reservoirs.
ISSN:0031-9015
1347-4073
DOI:10.7566/JPSJ.87.054006