Dynamic response of a mesoscopic capacitor in the presence of strong electron interactions

We consider a one dimensional mesoscopic capacitor in the presence of strong electron interactions and compute its admittance in order to probe the universal nature of the relaxation resistance. We use a combination of perturbation theory, renormalization group arguments, and quantum Monte Carlo calculation to treat the whole parameter range of dot-lead coupling. The relaxation resistance is universal even in the presence of strong Coulomb blockade when the interactions in the wire are sufficiently weak. We predict and observe a quantum phase transition to an incoherent regime for a Luttinger parameter $K<1/2$. Results could be tested using a quantum dot coupled to an edge state in the fractional quantum Hall effect.Comment: 4 pages, 4 figures, submitted to PR

Chiral condensate with topological degeneracy in graphene and its manifestation in edge states

Role of chiral symmetry in many-body states of graphene in strong magnetic fields is theoretically studied with the honeycomb lattice model. For a spin-split Landau level where the leading electron-electron interaction is the nearest-neighbor repulsion, a chiral condensate is shown to be, within the subspace of n = 0 Landau level, an exact many-body ground state with a finite gap, for which calculation of Chern numbers reveals that the ground state is a Hall insulator with a topological degeneracy of two. The topological nature of the ground state is shown to manifest itself as a Kekul\'ean bond order along armchair edges, while the pattern melts in the bulk due to quantum fluctuations. The whole story can be regarded as a realization of the bulk-edge correspondence peculiar to the chiral symmetry.Comment: 5 pages, 4 figures, submitted to PR

Quantum phase transition of dynamical resistance in a mesoscopic capacitor

We study theoretically dynamic response of a mesoscopic capacitor, which consists of a quantum dot connected to an electron reservoir via a point contact and capacitively coupled to a gate voltage. A quantum Hall edge state with a filling factor nu is realized in a strong magnetic field applied perpendicular to the two-dimensional electron gas. We discuss a noise-driven quantum phase transition of the transport property of the edge state by taking into account an ohmic bath connected to the gate voltage. Without the noise, the charge relaxation for nu>1/2 is universally quantized at R_q=h/(2e^2), while for nu<1/2, the system undergoes the Kosterlitz-Thouless transtion, which drastically changes the nature of the dynamical resistance. The phase transition is facilitated by the noisy gate voltage, and we see that it can occur even for an integer quantum Hall edge at nu=1. When the dissipation by the noise is sufficiently small, the quantized value of R_q is shifted by the bath impedance.Comment: 5 pages, 2 figures, proceeding of the 19th International Conference on the Application of High Magnetic Fields in Semiconductor Physics and Nanotechnology (HMF-19

Spin-resolved chiral condensate as a spin-unpolarized ν=0 quantum Hall state in graphene

Motivated by the recent experiments indicating a spin-unpolarized ν=0 quantum Hall state in graphene, we theoretically investigate the ground state based on the many-body problem projected onto the n=0 Landau level. For an effective model with the on-site Coulomb repulsion and antiferromagnetic exchange couplings, we show that the ground state is a doubly degenerate spin-resolved chiral condensate in which all the zero-energy states with up spin are condensed into one chirality, while those with down spin to the other. This can be exactly shown for an Ising-type exchange interaction. The charge gap due to the on-site repulsion in the ground state is shown to grow linearly with the magnetic field, in qualitative agreement with the experiments

Environmental Disinfection by Hypochlorous Acid Solution

Weak Acid Hypochlorous Solution (WAHS) has been used for disinfection of foods (meats, vegetables etc.), and for environmental disinfection in the Retirement homes, Hospitals and Laboratory Animal facilities. We will introduce here some of environmental disinfection tests. 1) To study whether WAHS is available or not for blood blot inoculated by Acinetobacter baumannii on the plate comparing with Sodium Hypochlorite. 2) Comparison of Ethanol and WAHS on the floor and handrail. 3) To study efficacy of shallowly dipping by WAHS on wagon caster inoculated by Staphylococcus aureus. The results are: 1) It was observed that WAHS had an efficacy equal to Hypochlorite with lower concentration in the blood test, but in case that the adhesion amount of blood was larger, much higher concentration or adding physical removal was needed. 2) Ethanol and WAHS had Equivalent efficacy on the test of floor and handrail. 3) It was suggested that shallowly dipping by WAHS was available for disinfection of wagon caster. We hope to proceed to confirm how to use WAHS for environmental disinfection

Fast and Slow Oscillation Electrooculography in Harada Disease

We assessed clinical utility of fast and slow oscillations (FO and SO) of the electrooculogram (EOG) in Harada disease. In 12 eyes of 4 female and 2 male subject patients aged 18 to 77 years (average: 41.8 years), FO and SO were recorded using an automated electrooculograph, the Nidek EOG-2, in the acute period before treatment and in the remission period under corticosteroid therapy. FO parameters, namely the RfFO [the average ratio in percentage of the maximum amplitude in the dark period (AD)/the minimum amplitude in the light period (AL) during FO measurement] and the dfFO (the average difference in ?V between AD and AL) were evaluated. The L/DSO (the light peak/dark trough ratio of the SO) was calculated as an SO parameter. The RfFO, dfFO and L/DSO showed low values in 7 (58.3%), 10 (83.3%) and 8 (66.7%) out of all 12 eyes in the acute period, respectively. In the remission period, values in the normal range were obtained in 12 (100%), 11 (91.7%) and 8 (66.7%) out of 12 eyes in the RfFO, dfFO and L/DSO, respectively. In mutual relation to each RfFO, dfFO and L/DSO in the acute and remission periods, all 12 eyes showed recovery values both in the RfFO and dfFO in the remission stage after systemic administration of corticosteroids, but 4 out of 12 eyes (33.3%) showed no recovery in the L/DSO. The FO may therefore well reflect the affected or ameliorated conditions in the outer layers of the retina and the choroid in Harada disease, in contrast to the SO. However, further observations are requested in more Harada disease patients