scholarly journals Finite-frequency current fluctuations and self-consistent perturbation theory for electron transport through a quantum dot

2013 ◽  
Vol 87 (23) ◽  
Author(s):  
Guo-Hui Ding ◽  
Bing Dong
Keyword(s):  
Perturbation Theory ◽  
Electron Transport ◽  
Quantum Dot ◽  
Current Fluctuations ◽  
Finite Frequency ◽  
Self Consistent ◽  
Frequency Current

Electron transport in quantum dot arrays: self-consistent modeling

2003 ◽  
Vol 19 (1-2) ◽  
pp. 188-191 ◽  
Author(s):  
M. Kobayashi ◽  
S. Miyahara ◽  
N. Mori ◽  
C. Hamaguchi
Keyword(s):  
Electron Transport ◽  
Quantum Dot ◽  
Self Consistent

scholarly journals Current Fluctuations in Hybrid-Superconductor Normal Structures with Quantum Dots

2021 ◽  
Author(s):  
◽  
Stephanie Droste
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Electronic Transport ◽  
Proximity Effect ◽  
Noise Spectrum ◽  
Current Fluctuations ◽  
Cooper Pairs ◽  
Finite Frequency ◽  
Strong Coulomb ◽  
Superconducting Correlations

<p>Nanostructures with quantum dots in proximity to superconducting electrodes are an ideal tool to study superconducting correlations in systems with few degrees of freedom that exhibit strong Coulomb-interaction effects. Such hybrid superconductor-normal structures show rich physics due to the interplay of superconductivity, Coulomb interaction and non-equilibrium. Superconducting correlations are established on the quantum dot when it is coupled to a superconductor even in the presence of strong Coulomb repulsion and Cooper pairs can tunnel coherently between the quantum dot and the superconductor.  In this thesis, we investigate theoretically electronic transport through an interacting quantum dot coupled to normal and superconducting leads. The presence of the proximity effect can be detected by the dot's current, namely the Andreev current. However, current fluctuations might reveal information on the electronic transport and the internal structure of the system which is not visible in the mean value of the current. For this reason, we study the current fluctuations through the proximized quantum dot to get access to the properties of such a hybrid quantum-dot system. In particular, we are interested in the finite-frequency fluctuations to unveil the coherent dynamics underlying the proximity effect in the quantum dot and its internal time scales.  At first, we present a study of the frequency-dependent current noise for subgap transport through an interacting single-level quantum dot tunnel-coupled to normal and superconducting leads. For this purpose, we employ a non-equilibrium diagrammatic real-time approach to calculate the finite-frequency current noise. The finite-frequency noise spectrum shows a sharp dip at a frequency corresponding to the energy splitting of the Andreev bound states which is a signature of the coherent exchange of Cooper pairs between the quantum dot and the superconductor. Furthermore, in the high frequency regime, the so called quantum noise regime, the noise spectrum exhibits steps at frequencies equal to the excitation energies. These steps can be related to the effective coupling strength of the excitations.  However, the statistical description of the electron transport does not stop with the noise. Current cumulants of arbitrary order can be obtained by means of full counting statistics (FCS). We set up a theory based on the diagrammatic real-time approach to calculate the finite-time FCS for quantum transport with a non-Markovian master equation that captures the initial correlations between system and reservoir. This allows us to fully describe the current fluctuations of the hybrid quantum-dot system, that is the noise and all higher order current cumulants.</p>

scholarly journals Current Fluctuations in Hybrid-Superconductor Normal Structures with Quantum Dots

2021 ◽  
Author(s):  
◽  
Stephanie Droste
Keyword(s):  
Quantum Dots ◽  
Quantum Dot ◽  
Electronic Transport ◽  
Proximity Effect ◽  
Noise Spectrum ◽  
Current Fluctuations ◽  
Cooper Pairs ◽  
Finite Frequency ◽  
Strong Coulomb ◽  
Superconducting Correlations

<p>Nanostructures with quantum dots in proximity to superconducting electrodes are an ideal tool to study superconducting correlations in systems with few degrees of freedom that exhibit strong Coulomb-interaction effects. Such hybrid superconductor-normal structures show rich physics due to the interplay of superconductivity, Coulomb interaction and non-equilibrium. Superconducting correlations are established on the quantum dot when it is coupled to a superconductor even in the presence of strong Coulomb repulsion and Cooper pairs can tunnel coherently between the quantum dot and the superconductor.  In this thesis, we investigate theoretically electronic transport through an interacting quantum dot coupled to normal and superconducting leads. The presence of the proximity effect can be detected by the dot's current, namely the Andreev current. However, current fluctuations might reveal information on the electronic transport and the internal structure of the system which is not visible in the mean value of the current. For this reason, we study the current fluctuations through the proximized quantum dot to get access to the properties of such a hybrid quantum-dot system. In particular, we are interested in the finite-frequency fluctuations to unveil the coherent dynamics underlying the proximity effect in the quantum dot and its internal time scales.  At first, we present a study of the frequency-dependent current noise for subgap transport through an interacting single-level quantum dot tunnel-coupled to normal and superconducting leads. For this purpose, we employ a non-equilibrium diagrammatic real-time approach to calculate the finite-frequency current noise. The finite-frequency noise spectrum shows a sharp dip at a frequency corresponding to the energy splitting of the Andreev bound states which is a signature of the coherent exchange of Cooper pairs between the quantum dot and the superconductor. Furthermore, in the high frequency regime, the so called quantum noise regime, the noise spectrum exhibits steps at frequencies equal to the excitation energies. These steps can be related to the effective coupling strength of the excitations.  However, the statistical description of the electron transport does not stop with the noise. Current cumulants of arbitrary order can be obtained by means of full counting statistics (FCS). We set up a theory based on the diagrammatic real-time approach to calculate the finite-time FCS for quantum transport with a non-Markovian master equation that captures the initial correlations between system and reservoir. This allows us to fully describe the current fluctuations of the hybrid quantum-dot system, that is the noise and all higher order current cumulants.</p>

scholarly journals On the detection of finite-frequency current fluctuations

JETP Letters ◽  
1997 ◽  
Vol 65 (3) ◽  
pp. 295-299 ◽  
Author(s):  
G. B. Lesovik ◽  
R. Loosen
Keyword(s):  
Current Fluctuations ◽  
Finite Frequency ◽  
Frequency Current

Electron transport in T-shaped double quantum dot structure

2021 ◽  
Vol 53 (8) ◽  
Author(s):  
Mohammed A. A. Abbas ◽  
Lafy F. Al-Badry ◽  
Amin H. Al-Khursan
Keyword(s):  
Electron Transport ◽  
Quantum Dot ◽  
Double Quantum ◽  
Double Quantum Dot

Remarkable lifetime improvement of quantum-dot light emitting diodes by incorporating rubidium carbonate in metal-oxide electron transport layers

2019 ◽  
Vol 7 (32) ◽  
pp. 10082-10091 ◽  
Author(s):  
Yujin Lee ◽  
Hyo-Min Kim ◽  
Jeonggi Kim ◽  
Jin Jang
Keyword(s):  
Electron Transport ◽  
Quantum Dot ◽  
Metal Oxide ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Remarkable Improvement ◽  
Operational Lifetime ◽  
Electron Transporting Layer ◽  
Doped Zno ◽  
Mg Doped

We demonstrated the remarkable improvement of efficiency roll-off and operational lifetime in red quantum dot light emitting diodes (R-QLEDs) by incorporating rubidium carbonate (Rb2CO3) in Mg doped ZnO (MZO) electron transporting layer (ETL).

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