Anisotropic charge Kondo effect in a triple quantum dot

Global Phase Diagram of a Spin-Orbital Kondo Impurity Model and the Suppression of Fermi-Liquid Scale

Many correlated metallic materials are described by Landau Fermi-liquid theory at low energies, but for Hund metals the Fermi-liquid coherence scale T_{FL} is found to be surprisingly small. In this Letter, we study the simplest impurity model relevant for Hund metals, the three-channel spin-orbital Kondo model, using the numerical renormalization group (NRG) method and compute its global phase diagram. In this framework, T_{FL} becomes arbitrarily small close to two new quantum critical points that we identify by tuning the spin or spin-orbital Kondo couplings into the ferromagnetic regimes. We find quantum phase transitions to a singular Fermi-liquid or a novel non-Fermi-liquid phase. The new non-Fermi-liquid phase shows frustrated behavior involving alternating overscreenings in spin and orbital sectors, with universal power laws in the spin (ω^{-1/5}), orbital (ω^{1/5}) and spin-orbital (ω^{1}) dynamical susceptibilities. These power laws, and the NRG eigenlevel spectra, can be fully understood using conformal field theory arguments, which also clarify the nature of the non-Fermi-liquid phase.

Rapid detection of quantum dot immune chromatography nasopharyngeal carcinoma EBNA1 antibody

This study explored the 605 nm carboxyl of water-soluble quantum dots to assess the practicability of the nasopharyngeal carcinoma marker EBNA1 antibody. We used 605 nm carboxyl water-soluble quantum dots and nasopharyngeal carcinoma EBNA1 antigen in 1-(3-dimethylaminopropyl-3-2-ethylcarbonimine hydrochloride to generate quantum dot-labeled antigen. Gel imaging system showed that serum group and 60 patients with nasopharyngeal carcinoma had significant differences in 30 cases of normal adult serogroup brightness, Levene test in the two groups ELISA absorbance value was P<0.001, namely the nasopharyngeal carcinoma group and the normal adult serum group measured absorbance value difference was obvious. The statistical significance, and the detection technology were of high specificity and sensitivity. In conclusion, this study adopted double antigen clip combining immune chromatography test EBNA1 antibody in serum, compared with the traditional enzyme-linked immunoassays this method is more rapid, with simpler operation, rapid detection for developing quantum dot immune chromatography technology the EBNA1 antibody kit provides a theoretical basis.

Suppressed Kondo effect and Kosterlitz-Thouless-type phase transition induced by level difference in a triple dot device

Quantum dot system provides an ideal platform for quantum information processing, within which to demonstrate the quantum states is one of the most important issue for quantum simulation and quantum computation. In this paper, we report a peculiar electron state in a parallel triple dot device where the Ruderman-Kittel-Kasuya-Yosida interaction is invalid when the level differences of the dots sweep into appropriate regime. This extraordinary tendency then results in an antiferromagnetic spin coupling between two of the dots and may lead to zero or full conductance, relying deeply on the relation of the two level spacings. e.g. when the level differences are kept equal, the Kondo effect is totally suppressed although the dots are triply occupied, since in this case a local inter-dot transport loop is found to play an important role in the transmission coefficient. By contrast, when the differences are retained symmetric, the Kondo peak reaches nearly to its unitary limit, owing to that the inter-dot transport process is significantly suppressed. To approach these problems, voltage controllable quantum phase transitions of Kosterlitz-Thouless type and first order are shown, and possible pictures related to the many-body effect and the effective Kondo model are given.