Shot noise in metallic double dot structures with a negative differential conductance

Nguyen, Vu Quoc Huy; Nguyen, V. Lien; Dollfus, Philippe

doi:10.1063/1.2053371

Cited by 14 publications

(26 citation statements)

References 12 publications

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“…Particularly, in the limit of zero frequency, when all the noises, for the net current and for currents through partial junctions, are coincident, 16 we found an explicit expression for Fano factor 21 F n ϵ S͑0͒/2eI = 1…”

Section: ͑9͒mentioning

confidence: 98%

“…Similarly, we can also obtain the noise expression for currents through junctions, I 1 or I 2 . 16 Thus, using the tunneling rates ͑3͒, in principle, we can solve the ME ͑4͒ and further to calculate the current ͑5͒ and the noise ͑6͒. In practice, however, this ME cannot be exactly solved with all possible states except some simple cases at low bias voltages.…”

mentioning

confidence: 99%

“…2,[10][11][12][13][14][15][16] Mathematically, the measure of these deviations is the Fano factor F n , defined as the ratio of the actual noise spectral density to the full SN value 2eI, where e is the elementary charge and I is the average current. Physically, it is widely accepted that the Pauli exclusion and the charge interaction are the two correlations, which cause observed SN deviations.…”

mentioning

confidence: 99%

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Super-Poissonian noise in a Coulomb-blockade metallic quantum dot structure

Nguyen¹,

Nguyen²

2006

Phys. Rev. B

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The shot noise of the current through a single electron transistor, coupled capacitively with an electronic box, is calculated, using the master equation approach. We show that the noise may be sub-Poissonian or strongly super-Poissonian, depending mainly on the box parameters and the gate. The study also supports the idea that not negative differential conductance, but charge accumulation in the quantum dot, responds for the super-Poissonian noise observed.Deviations of the shot noise ͑SN͒ from the full ͑Poisso-nian͒ value in nanostructures have been the subject of a great number of works, both experimental 1-9 and theoretical. 2,10-16 Mathematically, the measure of these deviations is the Fano factor F n , defined as the ratio of the actual noise spectral density to the full SN value 2eI, where e is the elementary charge and I is the average current. Physically, it is widely accepted that the Pauli exclusion and the charge interaction are the two correlations, which cause observed SN deviations. While the Pauli exclusion always causes a suppression of SN, the charge correlation may suppress or enhance the noise, depending on the conduction regime. The typical nonPoissonian behaviors of SN can be found in resonant tunneling diodes ͑RTD͒, where the noise is partially suppressed ͑sub-Poissonian noise͒ at low bias voltages ͑preresonance͒ and becomes very large ͑super-Poissonian͒ in the negative differential conductance ͑NDC͒ region. 2,3,6,8,12 For Coulomb blockade quantum dot ͑QD͒ structures, a suppression of SN is widely demonstrated, both experimentally 1,4,9 and theoretically. 10,11,13,14 Recently, 16 we have shown that in a system of two metallic QDs, coupled in series, the SN is always sub-Poissonian even in NDC regions. However, in some particular QD structure, as that considered in Ref. 5, a positive correlation in the electronic motion through QDs, leading to a super-Poissonian noise, might be developed. In this paper we will show that even in a simple structure of a symmetrical single electron transistor ͑SET͒, coupled capacitively to an electronic box, as that measured in Ref. 17, the super-Poissonian noise can be easily realized even in a positive differential conductance ͑PDC͒ region. Furthermore, in consistency with Refs. 6 and 7, our study supports the idea that the charge accumulation, not NDC, is ultimately responsible for the super-Poissonian noise observed.The equivalent circuit diagram of the structure studied is drawn in Fig. 1͑a͒, where the left QD ͑D͒ forms a SET, while the right QD ͑B͒ acts as an electronic box. Two QDs are coupled to each other by a capacitance C m , but the electron tunneling between them is forbidden. The current through the SET depends not only on the bias voltage V and the gate voltage V g , but also on the charge state in the box. Such a SET-to-box coupling may produce a NDC as experimentally observed in Ref. 17. Within the framework of the Orthodox theory 18 the state ͉iϾ of the system under study is entirely determined by the numbers of excess electrons in two QDs, ...

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Section: ͑9͒mentioning

confidence: 98%

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confidence: 99%

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confidence: 99%

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Super-Poissonian noise in a Coulomb-blockade metallic quantum dot structure

Nguyen¹,

Nguyen²

2006

Phys. Rev. B

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“…29 There are also some theoretical studies on the NDC effect in those systems, using models beyond the mean-field approximation. [30][31][32][33][34][35][36] In our work, electron interactions at the dots are treated within a mean-field approach. This approximation, plus additional correlations introduced through couplings to the F/S electrodes, gives rise to NDC effects.…”

Section: Introductionmentioning

confidence: 99%

Andreev tunneling through a double quantum-dot system coupled to a ferromagnet and a superconductor: Effects of mean-field electronic correlations

Siqueira

Cabrera

2010

Phys. Rev. B

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We study the transport properties of a hybrid nanostructure composed of a ferromagnet, two quantum dots, and a superconductor connected in series. By using the nonequilibrium Green's function approach, we have calculated the electric current, the differential conductance, and the transmittance for energies within the superconductor gap. In this regime, the mechanism of charge transmission is the Andreev reflection, which allows for a control of the current through the ferromagnet polarization. We have also included interdot and intradot interactions, and have analyzed their influence through a mean-field approximation. In the presence of interactions, Coulomb blockade tend to localize the electrons at the double-dot system, leading to an asymmetric pattern for the density of states at the dots, and thus reducing the transmission probability through the device. In particular, for nonzero polarization, the intradot interaction splits the spin degeneracy, reducing the maximum value of the current due to different spin-up and spin-down densities of states. Negative differential conductance appears for some regions of the voltage bias, as a result of the interplay of the Andreev scattering with electronic correlations. By applying a gate voltage at the dots, one can tune the effect, changing the voltage region where this novel phenomenon appears. This mechanism to control the current may be of importance in technological applications.

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“…Theoretical studies of NDR in this regime have also started gaining a lot of prominence in recent times [85,86,87]. Mean field descriptions are known to usually fail here, as electron charging energies are very high as compared to the broadenings due to the electrode coupling [88,89].…”

Section: Ndr In Double Quantum Dots In the Coulomb Blockade Regimementioning

confidence: 99%

Molecular Electronics: Effect of External Electric Field

2008

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The effect of electric field, applied on systems in the nanoscale regime has attracted a lot of research in recent times. We highlight some of the recent results in the field of single molecule electronics and then move on to focus on some of our own results in this area.We have first shown how important it is to obtain the spatial profile of the external bias potential across the system, and how this would change in the presence of electron-electron interactions. We have also studied different kinds of insulators in the presence of the spatially varying external bias, and have explicitly shown that a two sublattice structure, caused either by a lattice distortion, or by the presence of substituents with strong dipolar nature, can result in negative differential resistance (NDR) in the transport characteristics. We also find this to be true in case of correlated insulators. Additionally, we have shown clear NDR behavior in a correlated double quantum dot by tuning the electron-electron interaction strength in the system.

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Shot noise in metallic double dot structures with a negative differential conductance

Cited by 14 publications

References 12 publications

Super-Poissonian noise in a Coulomb-blockade metallic quantum dot structure

Super-Poissonian noise in a Coulomb-blockade metallic quantum dot structure

Andreev tunneling through a double quantum-dot system coupled to a ferromagnet and a superconductor: Effects of mean-field electronic correlations

Molecular Electronics: Effect of External Electric Field

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