Universal zero-bias conductance through a quantum wire side-coupled to a quantum dot

A numerical renormalization-group study of the conductance through a quantum wire side-coupled to a quantum dot is reported. The temperature and the dot-energy dependence of the conductance are examined in the light of a recently derived linear mapping between the Kondo-regime temperature-dependent conductance and the universal function describing the conductance for the symmetric Anderson model of a quantum wire with an embedded quantum dot. Two conduction paths, one traversing the wire, the other a bypass through the quantum dot, are identified. A gate potential applied to the quantum wire is shown to control the flow through the bypass. When the potential favors transport through the wire, the conductance in the Kondo regime rises from nearly zero at low temperatures to nearly ballistic at high temperatures. When it favors the dot, the pattern is reversed: the conductance decays from nearly ballistic to nearly zero. When the fluxes through the two paths are comparable, the conductance is nearly temperature-independent in the Kondo regime, and a Fano antiresonance in the fixed-temperature plot of the conductance as a function of the dot energy signals interference. Throughout the Kondo regime and, at low temperatures, even in the mixed-valence regime, the numerical data are in excellent agreement with the universal mapping.Comment: 12 pages, with 9 figures. Submitted to PR

Doping evolution of the electronic specific heat coefficient in slightly-doped La2-xSrxCuO4 single crystals

Detailed doping dependence of the electronic specific heat coefficient gamma is studied for La2-xSrxCuO4 (LSCO) single crystals in the slightly-doped regime. We find that gamma systematically increases with doping, and furthermore, even for the samples in the antiferromagnetic (AF) regime, gamma already acquires finite value and grows with x. This suggests that finite electronic density of states (DOS) is created in the AF regime where the transport shows strong localization at low temperatures, and this means the system is not a real insulator with a clear gap even though it still keeps long range AF order.Comment: 4 pages, 4 figures, accepted for publication in Journal of Physics: Conference Series (LT25 proceeding

Spectral resolution of the Liouvillian of the Lindblad master equation for a harmonic oscillator

A Lindblad master equation for a harmonic oscillator, which describes the dynamics of an open system, is formally solved. The solution yields the spectral resolution of the Liouvillian, that is, all eigenvalues and eigenprojections are obtained. This spectral resolution is discussed in depth in the context of the biorthogonal system and the rigged Hilbert space, and the contribution of each eigenprojection to expectation values of physical quantities is revealed. We also construct the ladder operators of the Liouvillian, which clarify the structure of the spectral resolution.Comment: 22pages, no figure; title changed, minor corrections, references added; minor correction

Thermal dependence of the zero-bias conductance through a nanostructure

We show that the conductance of a quantum wire side-coupled to a quantum dot, with a gate potential favoring the formation of a dot magnetic moment, is a universal function of the temperature. Universality prevails even if the currents through the dot and the wire interfere. We apply this result to the experimental data of Sato et al.[Phys. Rev. Lett. 95, 066801 (2005)].Comment: 6 pages, 3 figures. More detailed presentation, and updated references. Final version

β-Catenin mutations and aberrant nuclear expression during endometrial tumorigenesis

To clarify the possible role of aberrant β-catenin expression during endometrial tumorigenesis, a total of 199 cases of endometrial carcinomas (endometrioid type), as well as 37 cases of simple/complex and 32 of atypical hyperplasias, was consecutively investigated for immunohistochemistry, along with 141 normal endometrial samples distant from carcinomas. Of 199 carcinoma cases, 73 tumours as well as 44 normal samples were also analysed using a combination of RT-PCR and Southern blot hybridization, Western blot, and mutation gene assays. Cell membrane β-catenin immunoreactivity showed a stepwise decrease from normal, through atypical hyperplasia, to grade 3 carcinomas. In contrast, the nuclear accumulation in atypical hyperplasias and grade 1 or 2 tumours was higher than in simple/complex hyperplasias. Mutations in exon 3 of the β-catenin gene involving codons 33, 34, 37, 41, and 45 were observed in 16 (22.9%) of 70 endometrial carcinomas, as well as 3 (12.5%) of 24 atypical hyperplasias, the results being significantly related to low membrane and high nuclear immunoreactivity but not relative mRNA expression levels, suggesting that the gene mutations may be closely associated with changes in subcellular distribution. In addition to significant association between β-catenin mutation and low grade histological malignancy (P = 0.048), the mutations were detected in none of 15 and 13 (26%) of 50 tumours with or without lymph node metastasis, the difference being significant (P = 0.027). These findings suggest that β-catenin abnormalities may play an important role in a relatively early event during the endometrial hyperplasia-carcinoma sequence. © 2001 Cancer Research Campaign http://www.bjcancer.co

Real Space Imaging of Spin Polarons in Zn Doped SrCu2(BO3)2

We report on the real space profile of spin polarons in the quasi two-dimensional frustrated dimer spin system SrCu2(BO3)2 doped with 0.16% of Zn. The 11B nuclear magnetic resonance spectrum exhibits 15 additional boron sites near non-magnetic Zn impurities. With the help of exact diagonalizations of finite clusters, we have deduced from the boron spectrum the distribution of local magnetizations at the Cu sites with fine spatial resolution, providing direct evidence for an extended spin polaron. The results are confronted with those of other experiments performed on doped and undoped samples of SrCu2(BO3)2.Comment: 9 pages, 11 figures, including supplemental materials. accepted for publication in PR

On the Possible Common Nature of Double Extensive Air Showers and Aligned Events

Double Extensive Air Showers and aligned events were discovered at energies E {\gtsim} 1016 eV over fourth century back. But up to now there is no sufficiently identical explanation of their nature. In this paper it is expected that both types of events are the result of breakup of the string formed in the collisions of super high energy particles

Reversing Single Sessions

Session-based communication has gained a widespread acceptance in practice as a means for developing safe communicating systems via structured interactions. In this paper, we investigate how these structured interactions are affected by reversibility, which provides a computational model allowing executed interactions to be undone. In particular, we provide a systematic study of the integration of different notions of reversibility in both binary and multiparty single sessions. The considered forms of reversibility are: one for completely reversing a given session with one backward step, and another for also restoring any intermediate state of the session with either one backward step or multiple ones. We analyse the costs of reversing a session in all these different settings. Our results show that extending binary single sessions to multiparty ones does not affect the reversibility machinery and its costs