Realization of SU(N) Kondo effect in strong magnetic field

In this paper we suggest a realization for the SU(N) Kondo effect, using quantum dots at strong magnetic field. We purpose using edge states of the quantum Hall effect as pseudo spin that interact with multiple quantum dots structures. In the suggested realization one can access each pseudo spin separately and hence may perform a set of experiments that were impossible until now. We focus on the realization of SU(2) and SU(3) Kondo and find a conductivity of 3/4 quantum conductance in the SU(3) case.Comment: 5 pages, 2 figures. Including supplementary materia

On the Time Dependence of Holographic Complexity

We evaluate the full time dependence of holographic complexity in various eternal black hole backgrounds using both the complexity=action (CA) and the complexity=volume (CV) conjectures. We conclude using the CV conjecture that the rate of change of complexity is a monotonically increasing function of time, which saturates from below to a positive constant in the late time limit. Using the CA conjecture for uncharged black holes, the holographic complexity remains constant for an initial period, then briefly decreases but quickly begins to increase. As observed previously, at late times, the rate of growth of the complexity approaches a constant, which may be associated with Lloyd's bound on the rate of computation. However, we find that this late time limit is approached from above, thus violating the bound. Adding a charge to the eternal black holes washes out the early time behaviour, i.e., complexity immediately begins increasing with sufficient charge, but the late time behaviour is essentially the same as in the neutral case. We also evaluate the complexity of formation for charged black holes and find that it is divergent for extremal black holes, implying that the states at finite chemical potential and zero temperature are infinitely more complex than their finite temperature counterparts.Comment: 52+31 pages, 30 figure

On the Time Dependence of Holographic Complexity

We evaluate the full time dependence of holographic complexity in various eternal black hole backgrounds using both the complexity=action (CA) and the complexity=volume (CV) conjectures. We conclude using the CV conjecture that the rate of change of complexity is a monotonically increasing function of time, which saturates from below to a positive constant in the late time limit. Using the CA conjecture for uncharged black holes, the holographic complexity remains constant for an initial period, then briefly decreases but quickly begins to increase. As observed previously, at late times, the rate of growth of the complexity approaches a constant, which may be associated with Lloyd's bound on the rate of computation. However, we find that this late time limit is approached from above, thus violating the bound. Adding a charge to the eternal black holes washes out the early time behaviour, i.e., complexity immediately begins increasing with sufficient charge, but the late time behaviour is essentially the same as in the neutral case. We also evaluate the complexity of formation for charged black holes and find that it is divergent for extremal black holes, implying that the states at finite chemical potential and zero temperature are infinitely more complex than their finite temperature counterparts.Comment: 52+31 pages, 30 figure

A novel approach to study realistic navigations on networks

We consider navigation or search schemes on networks which are realistic in the sense that not all search chains can be completed. We show that the quantity $\mu = \rho/s_d$, where $s_d$ is the average dynamic shortest distance and $\rho$ the success rate of completion of a search, is a consistent measure for the quality of a search strategy. Taking the example of realistic searches on scale-free networks, we find that $\mu$ scales with the system size $N$ as $N^{-\delta}$, where $\delta$ decreases as the searching strategy is improved. This measure is also shown to be sensitive to the distintinguishing characteristics of networks. In this new approach, a dynamic small world (DSW) effect is said to exist when $\delta \approx 0$. We show that such a DSW indeed exists in social networks in which the linking probability is dependent on social distances.Comment: Text revised, references added; accepted version in Journal of Statistical Mechanic

Enhanced shot noise in asymmetric interacting two level systems

We study a model of two interacting levels that are attached to two electronic leads, where one of the levels is attached very weakly to the leads. We use rate equations method to calculate the average current and the noise of electrons transmitted through the two levels. We show that the shot noise is enhanced due to the interactions and that the Fano factor depends on the properties of the couplings between the levels and the leads. We study both sequential tunneling and cotunneling processes and show that there is a range of parameters in which the cotunneling processes affect the noise significantly, even though most of the current is carried by sequential tunneling processes.Comment: Published versio

Asymptotic behavior of the Kleinberg model

We study Kleinberg navigation (the search of a target in a d-dimensional lattice, where each site is connected to one other random site at distance r, with probability proportional to r^{-a}) by means of an exact master equation for the process. We show that the asymptotic scaling behavior for the delivery time T to a target at distance L scales as (ln L)^2 when a=d, and otherwise as L^x, with x=(d-a)/(d+1-a) for ad+1. These values of x exceed the rigorous lower-bounds established by Kleinberg. We also address the situation where there is a finite probability for the message to get lost along its way and find short delivery times (conditioned upon arrival) for a wide range of a's

Feminist avenues for listening in: amplifying silenced histories of media and communication

This paper proposes a feminist critique of the media and communication field by offering a different soundtrack to guide future historical research. By shifting the focus from well-known protagonists, and acknowledging process and community rather than individuals, we aim to amplify ‘hidden’ domains of gendered labour and layers of media technologies and services. We propose the ‘listening in’ model as a different way to engage with histories of media and communication, providing four pathways for how the histories of film, radio and internet in particular have been theorised and researched. These pathways focus on multiplicities of expertise, layers of infrastructure, users, and the media canon. For the first pathway, we show how media production has always been a collective work of multiple expertise. The second pathway breaks with the distinction between media and communication and emphasises reciprocal processes of media production. For the third, we demonstrate how media theory and research have tended to assume specific ideal bodies while ignoring others. For the final pathway, we propose a rethinking of how media histories and theories are narrated via the usual protagonists and call for a new canon to achieve a richer and more nuanced understanding within the field

Pseudospin-Resolved Transport Spectroscopy of the Kondo Effect in a Double Quantum Dot

We report measurements of the Kondo effect in a double quantum dot (DQD), where the orbital states act as pseudospin states whose degeneracy contributes to Kondo screening. Standard transport spectroscopy as a function of the bias voltage on both dots shows a zero-bias peak in conductance, analogous to that observed for spin Kondo in single dots. Breaking the orbital degeneracy splits the Kondo resonance in the tunneling density of states above and below the Fermi energy of the leads, with the resonances having different pseudospin character. Using pseudospin-resolved spectroscopy, we demonstrate the pseudospin character by observing a Kondo peak at only one sign of the bias voltage. We show that even when the pseudospin states have very different tunnel rates to the leads, a Kondo temperature can be consistently defined for the DQD system.Comment: Text and supplementary information. Text: 4 pages, 5 figures. Supplementary information: 4 pages, 4 figure