Two-channel Kondo physics in two-impurity Kondo models

We consider the non-Fermi liquid quantum critical state of the spin-S two-impurity Kondo model, and its potential realization in a quantum dot device. Using conformal field theory (CFT) and the numerical renormalization group (NRG), we show the critical point to be identical to that of the two-channel Kondo model with additional potential scattering, for any spin-S. Distinct conductance signatures are shown to arise as a function of device asymmetry; with the `smoking gun' square-root behavior, commonly believed to arise at low-energies, dominant only in certain regimes.Comment: 4.5 pages (with 3 figures) + 9 pages (with 4 figures) supplementary materia

Roadmap to Majorana surface codes

Surface codes offer a very promising avenue towards fault-tolerant quantum computation. We argue that two-dimensional interacting networks of Majorana bound states in topological superconductor/semiconductor heterostructures hold several distinct advantages in that direction, both concerning the hardware realization and the actual operation of the code. We here discuss how topologically protected logical qubits in this Majorana surface code architecture can be defined, initialized, manipulated, and read out. All physical ingredients needed to implement these operations are routinely used in topologically trivial quantum devices. In particular, we show that by means of quantum interference terms in linear conductance measurements, composite single-electron pumping protocols, and gate-tunable tunnel barriers, the full set of quantum gates required for universal quantum computation can be implemented.Comment: 23 pages, 8 figure

Towards realistic implementations of a Majorana surface code

Surface codes have emerged as promising candidates for quantum information processing. Building on the previous idea to realize the physical qubits of such systems in terms of Majorana bound states supported by topological semiconductor nanowires, we show that the basic code operations, namely projective stabilizer measurements and qubit manipulations, can be implemented by conventional tunnel conductance probes and charge pumping via single-electron transistors, respectively. The simplicity of the access scheme suggests that a functional code might be in close experimental reach.Comment: 5 pages, 1 p. suppl.mat, PRL in pres

Local Magnetization in the Boundary Ising Chain at Finite Temperature

We study the local magnetization in the 2-D Ising model at its critical temperature on a semi-infinite cylinder geometry, and with a nonzero magnetic field $h$ applied at the circular boundary of circumference $\beta$. This model is equivalent to the semi-infinite quantum critical 1-D transverse field Ising model at temperature $T \propto \beta^{-1}$, with a symmetry-breaking field $\propto h$ applied at the point boundary. Using conformal field theory methods we obtain the full scaling function for the local magnetization analytically in the continuum limit, thereby refining the previous results of Leclair, Lesage and Saleur in Ref. \onlinecite{Leclair}. The validity of our result as the continuum limit of the 1-D lattice model is confirmed numerically, exploiting a modified Jordan-Wigner representation. Applications of the result are discussed.Comment: 9 pages, 3 figure

PERSEPSI DAN PARTISIPASI MASYARAKAT LOKAL DALAM PENGEMBANGAN WILAYAH DESTINASI PARIWISATA SUPER PRIORITAS LIKUPANG

ABSTRAK   Indonesia merupakan negara kepulauan yang potensial dengan sumber daya alam yang mampu menjadi daya tarik wisata. Pariwisata menjadi andalan dalam menarik wisatawan. Dalam upaya untuk memperkenalkan kepada seluruh dunia potensi pariwisata yang di miliki Indonesia, telah ditetapkan 5 Destinasi pariwisata super prioritas, salah satunya yaitu Likupang di Provinsi Sulawei Utara. Setelah ditetapkan, Likupang mulai dikembangkan sebagai kawasan wisata, namun ditemui permasalahan terkait kurangnya pemahaman dan keterlibatan dari masyarakat lokal dalam pengembangan DPSP. Untuk itu perlu dilakukan penelitian untuk menggali dan mengkaji lebih dalam persepsi dan partisipasi dari masyarakat lokal terhadap pengembangan DPSP Likupang. Penelitian ini dilakukan di Kec. Likupang Timur, pada kawasan pariwisata pesisir di Desa Pulisan, Desa Marinsow, Desa Kinunang dan Desa Maen. Metode penelitian yang digunakan adalah Deskriptif Kualitatif. Sampel responden sebanyak 80 responden dari masyarakat lokal. Dikumpulkan dengan Teknik wawancara, kuesioner dan observasi. Setelah dilakukan analisis secara kualitatif dengan skala Likert, didapati hasil bahwa persepsi masyarakat lokal terhadap pengembangan DPSP Likupang sudah cukup baik. Selain itu didapati hasil bahwa masyarakat lokal “Sering” berpartisipasi dalam upaya pengembangan DPSP Likupang.  Kata Kunci: Pariwisata, Destinasi Pariwisata Super Prioritas, Persepsi Masyarakat, Partisipasi Masyarakat   ABSTRACT  Indonesia is a potential archipelagic country with natural resources that can become a tourist attraction. Tourism is a mainstay in attracting tourists. In an effort to introduce to the world the tourism potential of Indonesia, 5 super priority tourism destinations have been set, one of which is Likupang - North Sulawesi. Once established, Likupang began to be developed as a tourist area, however, the community still lacked understanding and involvement from the local community in the development of the DPSP. For this reason, it is necessary to conduct research to explore and examine more deeply related to the perception and participation of local communities towards the development of the Likupang DPSP. This research was conducted in Kec. East Likupang, in tourism areas in Pulisan Village, Marinsow Village, Kinunang Village and Maen Village. The research method is Descriptive -Qualitative. Questionairres are distribiuted to 80 of respondents from local communities. Data also collected with interview techniques and observation. After doing the analysis, it was found that the local community's perception of the development of the Likupang DPSP was quite good. In addition, it was found that the local community “often” participated in the development of the Likupang DPSP. Keywords: Tourism, Super Priority Tourism Destinations, Public Perception, Public Participatio

Electron Pair Resonance in the Coulomb Blockade

We study many-body corrections to the cotunneling current via a localized state with energy $\epsilon_d$ at large bias voltages $V$. We show that the transfer of {\em electron pairs}, enabled by the Coulomb repulsion in the localized level, results in ionization resonance peaks in the third derivative of the current with respect to $V$, centered at $eV=\pm 2\epsilon_d/3$. Our results predict the existence of previously unnoticed structure within Coulomb-blockade diamonds.Comment: 5 pages, 4 figure