The foremost emphasis of this foundational research letter has been given on analytical investigation of an enhanced simulative study on shortwave infrared gains (SWIRGs) of In0.68Al0.08Ga0.24As/InP lasing nanoscale heterostructure for fiber optic cable communication applications under transverse electric and magnetic bi-modes at 300K. In the starting of this work, taking into account recent and emerging computational technology, an enhanced and improved effective mass theory for single and multi-sub-bands has been utilized to enumerate the appropriate SWIR gain parameters as well as electrons-holes (Es-Hs) levels of quasi-Fermi energies. Under advanced simulation, first of all, the salient computational performances of Es-Hs levels of quasi-Fermi sub-band energies versus injected carriers (1018 cm-3) at 300K have been analysed simulatively. Next, electric and magnetic transverse bi-modes induced several spectral performances of SWIR-gain with wavelengths of photons have also been investigated analytically. In spite of this, the prominent performances of SWIR-differential gain (10-16cm2) with injected carriers (1018 cm-3) under transverse electric and magnetic bi-modes at 300K have been analyzed dominantly. Throughout the results, the peak intensities of SWIR-gain are achieved at wavelengths 1330 nm and 1550 nm corresponding to two crests of SWIR-spectra respectively under transverse bi-modes. Consequently, this emitted SWIR light gain by In0.68Al0.08Ga0.24As/InP heterogeneous nanostructure of wavelengths ~ 1330 nm and 1550 nm can be substantially utilized in the applications of fiber optic cable communications in the transmission of SWIR-signals through the modern process of total internal reflection with minimal attenuations of SWIR-signals (in dB × km-1) owing to lowest fiber dispersions and fiber absorptions.
K. Alekseev, U. FeodorV.KusmartsevOulu, U. FinlandLoughborough
et al.
We discuss an effect of dc current and dc voltage (stopping bias) generation in a semiconductor superlattice subjected by an ac electric field and its phase-shifted n-th harmonic. In the low field limit, we find a simple dependence of dc voltage on a strength, frequency, and relative phase of mixing harmonics for an arbitrary even value of n. We show that the generated dc voltage has a maximum when a frequency of ac field is of the order of a scattering constant of electrons in a superlattice. This means that for typical semiconductor superlattices at room temperature operating in the THz frequency domain the effect is really observable. We also made a comparison of a recent paper describing an effect of a directed current generation in a semiconductor superlattice subjected by ac field and its second harmonic (n=2) [K.Seeger, Appl.Phys.Lett. 76(2000)82] with our earlier findings describing the same effect [K.Alekseev et al., Europhys. Lett. 47(1999)595; cond-mat/9903092 ]. For the mixing of an ac field and its n-th harmonic with n>=4, we found that additionally to the phase-shift controlling of the dc current, there is a frequency control. This frequency controlling of the dc current direction is absent in the case of n=2. The found effect is that, both the dc current suppression and the dc current reversals exist for some particular values of ac field frequency. For typical semiconductor superlattices such an interesting behavior of the dc current should be observable also in the THz domain. Finally, we briefly review the history of the problem of the dc current generation at mixing of harmonics in semiconductors and semiconductor microstructures.
The effect of Coulomb interaction upon superconductive proximity effect in disordered metals is studied, employing newly developed Keldysh functional approach (cond-mat/9907358). We have calculated subgap Andreev conductance between superconductor and 2D dirty film, as well as Josephson coupling via such a film. Both two qualitatively different Coulomb effects - suppression of the tunneling density of states and disorder-enchanced repulsion in the Cooper channel - are shown to be important at sufficiently low temperatures.
Two years ago the reasons for resistance to the fundamental vortex dynamics in super media emerged in 1990's were analyzed (cond-mat/0407007). Five "mistakes" were identified to explain this resistance. Given the current tremendous interest in vortex dynamics, it would be desirable to provide a progress report: A survey of literature reveals that 3 out 5 "mistakes" has in fact been confirmed by other researchers.
In a recent letter, (Phys. Rev. Lett. 82, 2892(1999); cond-mat/9808306) Kamien and Lubensky calculated the energy of the surface constructed via a linear superposition of screw dislocations in SmA phase, and obtained the positive (repulsive) sign of the long-range interaction between dislocations. We would like to object that this interaction is attractive. This conclusion can be important to explain the discontinuity of the TGB - SmA phase transition in chiral liquid crystals.
We comment on the recent paper by Scarola, Park, and Jain [Nature v. 406, p. 863 (2000); cond-mat/0012030] on a trial wavefunction calculation of pairing in a fractional quantum Hall system at nu=5/2. We point out two errors that invalidate the claimed calculations of a binding energy for Cooper pairs and of an energy gap for charged excitations.
We analyse the analog of the Kelvin-Helmholtz instability on free suface of a superfluid liquid. This instability is induced by the relative motion of superfluid and normal components of the same liquid along the surface. The instability threshold is found to be independent of the value of viscosity, but turns out to be lower than in absence of dissipation. The result is similar to that obtained for the interface between two sliding superfluids (with different mechanism of dissipation) and confirmed by the first experimental observation of the Kelvin-Helmholtz instability on the interface between A and B phases of superfluid helium-3 by Blaauwgeers et al. (cond-mat/0111343).
In the paper " Superconducting decay length in a ferromagnetic metal" by Gusakova, Kupriyanov and Golubov [Pis'ma v ZhETF 83, 487 (2006); cond-mat/0605137], the authors claim that they solved the linearized Eilenberger equation in the ferromagnetic region of an S/F heterostructure at arbitrary mean free path. In this comment we show that the solution suggested by the authors is not correct and explain details of the exact solution found by us in an earlier work several years ago (Phys. Rev. B 64, 134506, (2001).
In the recent years, several polynomial algorithms of a dynamical nature have been proposed to address the graph isomorphism problem. In this paper we propose a generalization of an approach exposed in cond-mat/0209112 and find that this dynamical algorithm is covered by a combinatorial approach. It is possible to infer that polynomial dynamical algorithms addressing graph isomorphism are covered by suitable polynomial combinatorial approaches and thus are tackled by the same weaknesses as the last ones.
In a Comment (cond-mat/0310030) on our recent paper on network glasses (Phys. Rev. Lett., 2003, 90, 085505), Micoulaut and Boolchand (MB) compare our predictions on glass transitions in network systems for the ratios of the transition temperatures TA/TG and TK/TG with experimental data. They claim significant differences between experiment and theory are seen and claim the lack of agreement is due to flaws in our theory. Their comparison of TA/TG is incorrect as they do not measure the same quantity that our theory predicts. The TK/TG comparison shows remarkable agreement between theory and experiment.
In a recent comment [cond-mat/9703106] Casati, Izrailev and Sokolov claim that our analysis of the quantum kicked rotor [Phys. Rev. Lett. 77, 4536 (1996), chao-dyn/9609014] seems to miss an important aspect, viz. the difference in behavior between rational and irrational values of the parameter T = tau/4pi (tau being the time between kicks). The fact of the matter is that our approach does depend very sensitively on the number theoretical properties of T. In our reply we show how the 'degree of rationality' is related to the topological aspects of our theory and point out the phenomenological consequences of this connection.
In a recent paper, http://xxx.lanl.gov/abs/cond-mat/0404041, J. Vanacken et al. reported experimental studies of crystals of Mn12-ac molecular nanomagnets in pulsed magnetic fields with sweep rates up to 4000 T/s. Steps in the magnetization curve were observed. The data were explained by collective dipolar relaxation. We give here an alternative explanation that is based on thermal avalanches triggered by defect molecules (faster relaxing species). These species are always present in Mn12-ac molecular nanomagnets. We propose a simple method to test this interpretation. Note also that we do not question the possibility of collective effects that are bassed on spin–spin interactions.