Study of Electromagnetically Induced Transparency using long-lived Singlet States

The long-lived singlet states are useful to study a variety of interesting quantum phenomena. In this work we study electromagnetically induced transparency using a two-qubit system. The singlet state acts as a `dark state' which does not absorb a probe radiation in the presence of a control radiation. Further we demonstrate that the simultaneous irradiation of probe and control radiations acts as a dynamical decoupling preserving the singlet state at higher correlation for longer durations.Comment: 4 pages, 4 figure

Ginzburg-Landau theory of noncentrosymmetric superconductors

The data of temperature dependent superfluid density $n_s(T)$ in Li$_2$Pd$_3$B and Li$_2$Pt$_3$B [Yuan {\it et al.}, \phrl97, 017006 (2006)] show that a sudden change of the slope of $n_s (T)$ occur at slightly lower than the critical temperature. Motivated by this observation, we microscopically derive the Ginzburg-Landau (GL) equations for noncentrosymmetric superconductors with Rashba type spin orbit interaction. Cooper pairing is assumed to occur between electrons only in the same spin split band and pair scattering is allowed to occur between two spin split bands. The GL theory of such a system predicts two transition temperatures, the higher of which is the conventional critical temperature $T_c$ while the lower one $T^*$ corresponds to the cross-over from a mixed singlet-triplet phase at lower temperatures to only spin-singlet or spin-triplet (depending on the sign of the interband scattering potential) phase at higher temperatures. As a consequence, $n_s (T)$ shows a kink at this cross-over temperature. We attribute the temperature at which sudden change of slope occurs in the observed $n_s (T)$ to the temperature $T^*$. This may also be associated with the observed kink in the penetration depth data of CePt$_3$Si. We have also estimated critical field near critical temperature.Comment: 7 pages, 1 figur

Using skewness and the first-digit phenomenon to identify dynamical transitions in cardiac models

Disruptions in the normal rhythmic functioning of the heart, termed as arrhythmia, often result from qualitative changes in the excitation dynamics of the organ. The transitions between different types of arrhythmia are accompanied by alterations in the spatiotemporal pattern of electrical activity that can be measured by observing the time-intervals between successive excitations of different regions of the cardiac tissue. Using biophysically detailed models of cardiac activity we show that the distribution of these time-intervals exhibit a systematic change in their skewness during such dynamical transitions. Further, the leading digits of the normalized intervals appear to fit Benford's law better at these transition points. This raises the possibility of using these observations to design a clinical indicator for identifying changes in the nature of arrhythmia. More importantly, our results reveal an intriguing relation between the changing skewness of a distribution and its agreement with Benford's law, both of which have been independently proposed earlier as indicators of regime shift in dynamical systems.Comment: 11 pages, 6 figures; incorporating changes as in the published versio

Efficacy and Safety of Stomatab Capsules® in Improving Oral Health in Recurrent Aphthous Stomatitis: An Open-labeled Clinical Study

Background: Recurrent aphthous stomatitis (RAS) is a common ulcerative disease of the oral mucosa, which is difficult to treat. In Ayurveda, several medicinal plants have been evaluated for their anti-inflammatory and antioxidant effects in many oral diseases as an alternative for modern medicines. Method: A study with open-label, non-comparative single-arm design was conducted to evaluate the efficacy of “Stomatab” capsules in improving oral health in 30 subjects with RAS. The secondary objectives were to assess the improvement in oral health and tolerability of the herbal formulation. Subjects were instructed to take one capsule thrice daily after meals for 14 days. Patients were evaluated at three assessment points: screening and baseline (Visit 1, Day 0) with follow-ups done at Visit 2 (Day 5 ± 2) and Visit 3 at the end of the study (Day 14 ± 2). Results: There was a significant reduction in the mean ulcer size from 3.66 ± 1.27 mm (V1) to 0.64 ± 0.78 (V3). The mean number of ulcers reduced from 1.97 ± 0.72 (V1) to 0.90 ± 0.66 (V3). Significant improvement in ulcer-related symptoms of pain (Ruja), burning sensation (Daha) and redness (Raktavarnata) was noted. The total ulcer symptom scores decreased from 7.67 ± 2.38 (V1) to 0.63 ± 0.56 (V3). No side effects were reported by the study participants. Conclusion: These results show that the polyherbal formulation “Stomatab” capsule is safe and effective for the treatment of RAS

Hierarchical Search Strategy for the Detection of Gravitational Waves from Coalescing Binaries

The detection of gravitational waves from coalescing compact binaries would be a computationally intensive process if a single bank of template wave forms (i.e., a one-step search) is used. We present, in this paper, a method which leads to a large reduction in the computational power required as compared to a one-step search. This method is a hierarchical search strategy involving two template banks. We show that the computational power required by such a two-step search, for an on-line detection of the one-parameter family of Newtonian signals, is 18 of that required when an on-line one-step search is used. This reduction is achieved when signals having a strength of ∼8.8 are required to be detected with a probability of ∼0.95 and an average of one false event per year. We present approximate formulas for the detection probability of a signal and the false alarm probability. We investigate the effect of statistical correlations on these probabilities and incorporate these effects whereever possible. Our numerical results are specific to the noise power spectral density expected for the initial LIGO

Manifestation of helical edge states as zero-bias magneto-tunneling-conductance peaks in non-centrosymmetric superconductors

Helical edge states exist in the mixed spin-singlet and -triplet phase of a noncentrosymmetric superconductor (NCSS) when the pair amplitude (PA) in the negative helicity band, $\Delta_-$, is smaller than the PA in the positive helicity band, $\Delta_+$, i.e., when the PA in the triplet component is more than the same in the singlet component. We numerically determine energies of these edge states as a function of $\gamma = \Delta_-/\Delta_+$. The presence of these edge states is reflected in the tunneling process from a normal metal to an NCSS across a bias energy $eV$: (i) Angle resolved spin conductance (SC) obeying the symmetry $g_s(\phi) =-g_s(-\phi)$ shows peaks when the bias energy equals the available quasiparticle edge state energy provided $|eV| \lesssim \Delta_-$. (ii) The total SC, $G_s$, is zero but modulates with $eV$ for finite magnetic field $H$. (iii) The zero bias peaks of $G_s$ and total charge conductance, $G_c$, at finite $H$ split into two at finite $eV$ for moderate $H$. (iv) At zero bias, $G_c$ and $G_s$ increase with $H$ and show peaks at $|H|\sim \gamma H_0$ where $H_0$ is a characteristic field.Comment: minor changes; one figure is adde