ac conductance and nonsymmetrized noise at finite frequency in quantum wires and carbon nanotubes

Safi, Inès; Bena, Cristina; Crépieux, Adeline

doi:10.1103/physrevb.78.205422

Cited by 38 publications

(51 citation statements)

References 66 publications

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“…It may be interesting to extend our studies of AC response to these systems. Finally, we note that the AC response of non-chiral Tomonaga-Luttinger liquids with disorder has been studied earlier in some papers [38,39,40,41].…”

Section: Discussionmentioning

confidence: 99%

AC conductivity of a quantum Hall line junction

Agarwal¹,

Sen²

2009

J. Phys.: Condens. Matter

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We present a microscopic model for calculating the AC conductivity of a finite length line junction made up of two counter or co-propagating single mode quantum Hall edges with possibly different filling fractions. The effect of density-density interactions and a local tunneling conductance (σ) between the two edges is considered. Assuming that σ is independent of the frequency ω, we derive expressions for the AC conductivity as a function of ω, the length of the line junction and other parameters of the system. We reproduce the results of Phys. Rev. B 78, 085430 (2008) in the DC limit (ω → 0), and generalize those results for an interacting system. As a function of ω, the AC conductivity shows significant oscillations if σ is small; the oscillations become less prominent as σ increases. A renormalization group analysis shows that the system may be in a metallic or an insulating phase depending on the strength of the interactions. We discuss the experimental implications of this for the behavior of the AC conductivity at low temperatures.

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Section: Discussionmentioning

confidence: 99%

AC conductivity of a quantum Hall line junction

Agarwal¹,

Sen²

2009

J. Phys.: Condens. Matter

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“…It was first investigated in strongly correlated systems such as the FQHE edge states [11], a coherent conductor in an ohmic environment, and quantum wires and carbon nanotubes connected to charge reservoirs [12]. In particular, the non-symmetrized excess noise was found to be asymmetric.…”

Section: Pacs Numbersmentioning

confidence: 99%

“…In particular, the non-symmetrized excess noise was found to be asymmetric. One could argue that such asymmetry needs Coulomb interactions to hold on, nevertheless the criteria was indeed discovered to be related to non-linearity [12,13], as we will be explained now. This enlightens a recent experiment measuring asymmetric FF excess noise in Josephson junctions [8].…”

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confidence: 99%

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Asymmetry of the excess finite-frequency noise

Safi¹,

Macucci²,

Basso³

2009

AIP Conference Proceedings

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We consider finite frequency noise in a mesoscopic system with arbitrary interactions, connected to many terminals kept at finite electrochemical potentials. We show that the excess noise, obtained by subtracting the noise at zero voltage from that at finite voltage, can be asymmetric with respect to positive/negative frequencies if the system is non-linear. This explains a recent experimental observation in Josephson junctions as well as strong asymmetry obtained in typical non-linear and strongly correlated systems described by the Luttinger liquid (LL): edge states in the fractional quantum Hall effect, quantum wires and carbon nanotubes. Another important problem where the LL model applies is that of a coherent conductor embedded in an ohmic environment. PACS numbers:The finite frequency (FF) current fluctuations have attracted a lot of interest in the mesoscopic community [1,2]. It has been possible to measure them in the quantum regime, i. e. at frequencies higher than temperature. Beyond the average current, they offer a powerful tool to reveal the charge and statistics of the charge carriers of a system when considered at zero-frequency. Nevertheless, they contain more rich informations at FF, such as on elementary excitations, typical energy scales, and especially on interactions, with the possibility to check the underlying model or access the correlation strength etc...It has been often stated in theoretical studies that one needs to symmetrize the current correlators, as they don't commute at different times, which leads to a FF symmetrized noise, symmetric with respect to positive/negative frequencies. Nevertheless, this has been often explored by the scattering approach at low frequencies compared to characteristic energy scales [2]. Few theoretical works went beyond this framework [3]. It has also been studied in systems where interactions intervene at any frequency scale in the FF noise such as chiral edge states in the Fractional Quantum Hall effect (FQHE), quantum wires and carbon nanotubes, described by the Luttinger liquid (LL) model, which leads to exotic phenomena such as charge fractionalization [5], spin-charge separation, and fractional statistics. It has been shown that LL is suited as well to describe a coherent conductor embedded into an ohmic environment [4]. The symmetrized FF noise has been studied in the FQHE in Ref. [6], and in Refs. [7] for quantum wires and carbon nanotubes connected to metallic leads, where it was shown that, while the presence of the metallic leads obscures it in the zero-frequency noise, the charge fractionalization is still present and can be extracted from the noise at high frequencies.Nevertheless, recent experiments [8] have got access to the non-symmetrized noise [9], and thus to the emission and the absorption components of the noise spectrum given by the noise at positive/negative frequencies. What is usually measured is the excess non-symmetrized noise, defined as the difference between the noise at finite voltage and at zero voltage, thus allowing t...

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“…[10][11][12] This experimental progress has since triggered renewed theoretical interest in time-dependent mesoscopic transport. [13][14][15][16][17][18] One way to tackle the ac-transport problem is to start from linear-response theory for a given potential distribution of the sample. [19][20][21] This involves the difficulty that, in principle, the potential distribution and more precisely its link to the screening is unknown.…”

Section: Introductionmentioning

confidence: 99%

Semiclassical approach to the ac conductance of chaotic cavities

et al. 2009

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We address frequency-dependent quantum transport through mesoscopic conductors in the semiclassical limit. By generalizing the trajectory-based semiclassical theory of dc quantum transport to the ac case, we derive the average screened conductance as well as ac weak-localization corrections for chaotic conductors. Thereby we confirm respective random matrix results and generalize them by accounting for Ehrenfest time effects. We consider the case of a cavity connected through many leads to a macroscopic circuit which contains ac sources. In addition to the reservoir the cavity itself is capacitively coupled to a gate. By incorporating tunnel barriers between cavity and leads we obtain results for arbitrary tunnel rates. Finally, based on our findings we investigate the effect of dephasing on the charge relaxation resistance of a mesoscopic capacitor in the linear low-frequency regime.

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ac conductance and nonsymmetrized noise at finite frequency in quantum wires and carbon nanotubes

Cited by 38 publications

References 66 publications

AC conductivity of a quantum Hall line junction

AC conductivity of a quantum Hall line junction

Asymmetry of the excess finite-frequency noise

Semiclassical approach to the ac conductance of chaotic cavities

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