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1
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Threshold Effects in Three-Terminal Hybrid Systems

100%
Michałek G.
|
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vol. 126
|
issue 1
224-225
EN
In the paper we study transport in the three terminal hybrid devices with quantum dot. Our attention is focused on the conductance threshold effects (so called Wigner singularities) caused by the back action from the side-wire. In particular we study influence of the direct electron transfer (ET) and crossed Andreev reflection (CAR) processes on the conductance caused by the direct Andreev reflection (DAR) processes.
2
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Enhancement of Current Auto- and Cross-Correlations in Double Quantum Dots

64%
Michałek G., Bułka B.
Acta Physica Polonica A
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2009
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vol. 115
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issue 1
117-119
EN
Studies of an enhancement of current shot noises are presented for a device of two large quantum dots coupled capacitively. We analyze current-current correlation functions, and show that a dynamical Coulomb blockade is responsible for an enhancement of the Fano factors. This process can lead also to an electron bunching and positive current cross-correlations. Our theoretical results are discussed in light of recent shot noise experiments.
3
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Interference Effects in Three-Terminal Hybrid Systems with Quantum Dots

64%
Michałek G., Bułka B.
Acta Physica Polonica A
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2012
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vol. 122
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issue 6
981-983
EN
Conductance in a three-terminal hybrid system with two quantum dots is analyzed. Our attention is focused on an influence of decoherence on interference effects in the Andreev transport. In particular, we have found that a change of coupling to the third electrode can strongly modify a shape of the Fano-type resonances. This effect is due to activation of nonlocal Andreev reflection (CAR) processes.
4
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Cross-Correlations and Charge Pumping in Shot Noise οf Coupled Quantum Dot System

64%
Michałek G., Bułka B.
Acta Physica Polonica A
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2009
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vol. 116
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issue 5
879-881
EN
We analyze current auto- and cross-correlations in the system of two capacitively coupled large quantum dots. Our attention is focused on the strong inter-dot coupling when an electron transfer through one of the quantum dots induces charge pumping through the second quantum dot. We show individual contributions to shot noise from various tunneling processes in the charge space.
5
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Current Shot Noise and Bunching of Electrons in Multilevel Quantum Dots

64%
Michałek G., Bułka B.
Acta Physica Polonica A
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2008
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vol. 113
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issue 1
27-30
EN
Currents and their fluctuations in multilevel quantum dots are studied theoretically in the limit of sequential tunneling. The spin degrees of freedom, many-body electronic states (singlet and triplet) as well as relaxation processes between the levels of the quantum dots are considered. In general, due to the rapid relaxation processes the shot noise is sub-Poissonian, however for a large polarization of the outgoing currents from the singlet and triplet states one gets the super-Poissonian type of the shot noise due to the bunching of tunneling events.
6
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Negative Differential Resistance and Super-Poissonian Shot Noise in a System of Single Electron Transistors

64%
Michałek G., Bułka B.
Acta Physica Polonica A
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2001
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vol. 100
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issue 3
431-436
EN
Currents and their fluctuations in two capacitively coupled single electron transistors were studied within the sequential tunneling approach. A special attention was focused on the effect of the negative differential resistance, which appears due to the Coulomb interactions of accumulated charges on both the single electron transistors. In this case large polarization fluctuations are activated, which results in a significant enhancement of the current shot noise.
7
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Current Fluctuations in Ferromagnetic Tunnel Junctions

51%
Bułka B., Martinek J., Michałek G., Barnaś J.
Acta Physica Polonica A
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2000
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vol. 97
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issue 3
423-426
EN
Current shot noise in a double junction consisting of a small metallic grain connected to two ferromagnetic electrodes is analysed in the limit of sequential tunneling. We show that, apart from charge fluctuations, there are strong spin fluctuations. We also show that two distinct relaxation processes can be distinguished in the frequency dependent current noise: one in a low frequency range and corresponding to spin fluctuations and another one in a high frequency range corresponding to charge fluctuations.
8
Content available remote

Statistics of Tunneling Events in Three-Terminal Hybrid Devices with Quantum Dot

51%
Michałek G., Bułka B., Domański T., Wysokiński K.
Acta Physica Polonica A
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2018
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vol. 133
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issue 3
391-393
EN
We investigate statistics of the tunneling events in the short time limit in terms of the waiting time distribution (WTD), defined as the probability for a delay time between two subsequent transitions of particles, and consider it for a quantum dot (QD) strongly coupled to a superconducting and weakly coupled to two normal electrodes. Our study focuses on the WTD in the subgap transport, when coherent exchange of the Cooper pairs occurs between the QD and the superconductor. The dynamics can be described in terms of a Markovian generalized master equation for the reduced density matrix. We observe coherent oscillations between the Andreev bound states in the correlated jumps, both for the local and non-local WTDs. In addition the analysis of the transient currents give us some insight into dominant relaxation processes in short time scales.
9
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Andreev Spectroscopy in Three-Terminal Hybrid Nanostructure

45%
Michałek G., Bułka B., Urbaniak M., Domański T., Wysokiński K.
Acta Physica Polonica A
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2015
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vol. 127
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issue 2
293-295
EN
We consider a hybrid three-terminal structure consisting of a quantum dot coupled to three leads, two normal and one superconducting. The current flowing between one of the normal and the superconducting electrodes induces voltage in the other normal (floating) electrode. The value of the induced voltage depends on the position of the Andreev levels in the quantum dot and is a measure of the interplay between the electron transfer and the subgap anomalous reflection processes. When the crossed (i.e. non-local) Andreev reflections dominate the induced potential in the normal electrode becomes negative. This situation occurs for the relatively strong coupling to the superconducting electrode and only outside the Coulomb blockade region. Taking the superconducting electrode as the voltage probe one gets additional information on competition of injected carriers.
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