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Graphene-based hyperbolic metamaterials have been predicted to transport evanescent fields with extraordinarily large vacuum wave-vectors. It is particularly at much higher wave vector values that the commonly employed descriptional models involving structure homogenization and assumptions of an approximatively local graphene conductivity start breaking down. Here, we combine a non-local quantum conductivity model of graphene with an exact mathematical treatment of the periodic structure in order to develop a tool-set for determining the hyperbolic behavior of these graphene-based hyperbolic metamaterials. The quantum conductivity model of graphene facilitates us to predict the plasmonic amplification in graphene sheets of the considered structures. This allows us to reverse the problem of Ohmic and temperature losses, making this simple yet powerful arrangement practically applicable. We analyze the electric field distribution inside of the finite structures, concluding that Bloch boundary solutions can be used to predict their behavior. With the transfer matrix method we show that at finite temperature and collision loss we can compensate for losses, restoring imaging qualities of the finite structure via an introduction of chemical imbalance.

We introduce a scheme where a time-dependent source excites “complex-frequency” modes in uniform plasmonic heterostructures, enabling complete and dispersionless stopping of light pulses, resilient to realistic levels of dissipative, radiative, and surface-roughness losses. Using transparent conducting oxides at telecommunication wavelengths we show how, without increasing optical losses, multiple light pulses can decay with time precisely at their injection points, unable to propagate despite the complete absence of barriers in front or behind them. Our results theoretically demonstrate extraordinary large light-deceleration factors (of the order of 1.5 × 10 7 ) in integrated nanophotonic media, comparable only to those attainable with ultracold atomic vapors or with quantum coherence effects, such as coherent population oscillations, in ruby crystals.

A Comment on the Letter by Mark I. Stockman, Phys. Rev. Lett. 106, 156802 (2011). The author of the Letter offers a Reply.

We report the existence of guided optical solitons of femtosecond duration and nanoscopic mode area. The proposed scheme exploits the structural confinement of light in a low-index subwavelength gap and the nonlinear interaction with a resonantly absorbing medium to achieve stable and ultraconcentrated coherent pulses. Employing full time- and space-dependent Maxwell-Bloch equations, we find that these extremely nonlinear, propagating impulses are quasisolitons, stabilized against dispersion and absorption by self-induced transparency at a laterally constant Rabi frequency.

We theoretically and numerically analyze a five-layer "trapped rainbow" waveguide made of a passive negative refractive index (NRI) core layer and gain strips in the cladding. Analytic transfer-matrix calculations and full-wave time-domain simulations are deployed to calculate, both in the frequency- and in the time-domain, the losses or gain experienced by complex-wavevector and complex-frequency modes. We find an excellent agreement between five distinct sets of results, all showing that the use of evanescent pumping (gain) can compensate the losses in the NRI slow-light regime.

On the basis of a full-vectorial three-dimensional Maxwell-Bloch approach we investigate the possibility of using gain to overcome losses in a negative refractive index fishnet metamaterial. We show that appropriate placing of optically pumped laser dyes (gain) into the metamaterial structure results in a frequency band where the nonbianisotropic metamaterial becomes amplifying. In that region both the real and the imaginary part of the effective refractive index become simultaneously negative and the figure of merit diverges at two distinct frequency points., Comment: 4 pages, 4 figures

We examine the dynamics of counterpropagating self-induced transparency solitons in three-level media. In a multilevel system, self-induced transparency gives rise to soliton solutions if the propagation is unidirectional, but the collision of counterpropagating pulses destroys the integrability of the underlying equations. We consider the collision of a rightward and a leftward moving self-induced transparency solitary wave by solving the full Maxwell-Bloch equations numerically using a finite-difference time-domain approach. Depending on pulse duration, amplitude and relative polarizations of the initial solitary waves we observe different regimes of interaction. For high group velocities and orthogonal polarizations, secondary solitary waves are born during the interaction, whereas the collision of solitary waves with the same polarization never produces secondary solitary waves but leaves behind a population grating in the interaction region. Because the crucial parameters can be controlled, an experimental confirmation of the predicted interaction regimes should be feasible.

tions, but currently their performance is limited by the occurrence of losses—particularly radiation losses, which dominate over their dissipative counterparts even in the optical regime. Here, a metamaterial configuration is conceived that judiciously generalizes the traditional electromagnetically induced transparency EIT scheme—by which radiation losses can be restrained—in such a way that EIT can be observed and exploited in negative-magnetic metamaterials. Analytic theory and three-dimensional simulations unveil the required route: introduction of poor-conductor meta-atoms next to the good-conductor meta-atoms of a magnetic metamaterial. This setup results in a frequency band where the metamaterial remains negative-magnetic, while its loss-performance dramatically improves owing to suppression of radiation damping. Furthermore, we show that placing the two meta-atoms on orthogonal planes gives rise to a passive anisotropic metamaterial exhibiting permeabilities with negative real parts Re 0 and active imaginary parts Im 0 for an e +it time

The reaction /sup 16/O(/sup 14/N, /sup 10/B)/sup 20/Ne was studied at 155 MeV. The reaction mechanism shows characteristics of a direct ..cap alpha.. transfer process with high-spin enhancement. Observed transitions are discussed in terms of high rotational bands, and high-spin members of the SU(3) (9,0) and (12,0) bands are assigned. (AIP)

The analog reactions /sup 16/O(/sup 10/B, /sup 7/Li)/sup 19/Ne and /sup 16/O(/sup 10/B, /sup 7/Be)/sup 19/F at 100 MeV have been utilized to study high-excitation, three-nucleon-cluster states in /sup 19/Ne and /sup 19/F. Deformed-model calculations have been made in order to predict the energies of such high-lying states in terms of rotational bands with one or more particles in the fp shell. These show that the high-lying levels seen in the data can be explained by (sd)/sup 2/(fp)/sup 1/ and (fp)/sup 3/ configurations outside an /sup 16/O core. (AIP)

An apparent puzzle concerning the suppression of heavy-ion-induced nn and pp transfers compared to np transfer in light nuclei can be explained to a great extent by invoking simple arguments based on the binding energies of the transferred pairs to the two cores. The manifestation of this effect is in the tail regions of the appropriate bound-state wave functions where transfer is well known to occur. These arguments may be extended to include multinucleon transfers where the consequences of this effect could be even more drastic.

A systematic study is made of 100 MeV $^{10}\mathrm{B}$-induced $2n$ and $2p$ transfer reactions on light targets of $^{12}\mathrm{C}$, $^{14}\mathrm{N}$, and $^{16}\mathrm{O}$. These reactions are seen to selectively populate only a few states in the residual nuclei, showing them to be useful for studying states of particular structures. Known states with ${({p}_{\frac{1}{2}}{d}_{\frac{5}{2}})}_{3}$- and $({d}_{\frac{5}{2}})_{}^{2}{}_{{4}^{+}}{}^{}$ structures are strongly populated in the $T=1$ mass-14 nuclei. The known $({d}_{\frac{5}{2}})_{}^{2}{}_{{4}^{+}}{}^{}$ states in the $T=1$ mass-18 nuclei are also strongly populated. The lowest ${2}^{+}$ states (also of a $d_{\frac{5}{2}}^{}{}_{}{}^{2}$ nature) in these latter nuclei are populated more weakly. Exact finite-range distorted-wave Born-approximation calculations, assuming a cluster transfer of the two neutrons or protons, are presented for the strongly populated levels in the mass-14 and -18 residual nuclei, and for the ${2}^{+}$ level in $^{18}\mathrm{O}$. With the exception of this ${2}^{+}$ state and the unbound ${4}^{+}$ state in $^{14}\mathrm{O}$, the shapes of the angular distributions are well fitted by the cluster approximation. The distorted-wave Born-approximation normalizations to the data are compared to cluster spectroscopic factors calculated from shell model wave functions for the various states involved. In most cases, the extracted factors agree with the calculated spectroscopic factors to within a factor of 3. This agreement suggests that the reaction mechanism is predominantly a one-step transfer of a $T=1$, $S=0$ pair of neutrons or protons. The known structures of the strongly populated states in the mass-14 and -18 nuclei can be used to interpret newly observed states in the mass-16 spectra, in which there are two groups of strongly populated levels in each nucleus. The doublet in the low excitation region corresponds to the known ${2}^{\ensuremath{-}}$ and ${3}^{\ensuremath{-}}$ states presumably populated through the transfer of the nucleon pair into a ${({p}_{\frac{1}{2}}{d}_{\frac{5}{2}})}_{3}$- configuration coupled to the $^{14}\mathrm{N}_{1+}$ target core. The higher group of states is predicted to arise from the transfer of the nucleon pair into a $({d}_{\frac{5}{2}})_{}^{2}{}_{{4}^{+}}{}^{}$ configuration coupled to the ${1}^{+}$ core. The results of a Bansal-French-Zamick weak coupling model calculation for the center of gravity of the triplet of states from this $({d}_{\frac{5}{2}})_{}^{2}{}_{{4}^{+}}{}^{}$ configuration in the $T=1$ mass-16 nuclei are presented. These are seen to be in agreement with the observed energies of the high excitation peaks in the data.[NUCLEAR REACTIONS $^{12}\mathrm{C}$, $^{14}\mathrm{N}$, $^{16}\mathrm{O}$($^{10}\mathrm{B}$, $^{8}\mathrm{Li}$), $E=100$ MeV; $^{12}\mathrm{C}$, $^{14}\mathrm{N}$, $^{16}\mathrm{O}$($^{10}\mathrm{B}$, $^{8}\mathrm{B}$), $E=100$ MeV; measured $\ensuremath{\sigma}(\ensuremath{\theta})$; DWBA analysis; extracted and calculated $2n$ and $2p$ spectroscopic factors; weak coupling model predictions.]

Proton and neutron transfer reactions resulting from the bombardment of $^{12}\mathrm{C}$ and $^{16}\mathrm{O}$ targets by $^{14}\mathrm{N}$ beams and $^{12}\mathrm{C}$, $^{14}\mathrm{N}$, and $^{16}\mathrm{O}$ targets by $^{10}\mathrm{B}$ beams have been studied with counter telescopes and particle identification techniques. The incident energies were far above the Coulomb barrier for these systems: 155 MeV for $^{14}\mathrm{N}$ ions and 100 MeV for $^{10}\mathrm{B}$ ions. Angular distributions have been measured for transitions to the ground states and several excited states in the residual nuclei produced. Ejectile excitations were also observed in some instances. Exact finite range distorted-wave-Born-approximation calculations have been performed for these states which are mostly in the $1p$ and $2s\ensuremath{-}1d$ shells. The extracted spectroscopic factors are generally in good agreement with theoretical predictions and other previously obtained results. However, there are some conspicuous but isolated instances where they are not, pointing towards a need for more sophisticated approaches including core excitations for those cases. Generally the quality of spectroscopic studies with heavy-ion-induced transfer reactions is comparable if not superior to that from the corresponding light-ion-induced reactions.NUCLEAR REACTIONS $^{12}\mathrm{C}$($^{14}\mathrm{N}$, $^{13}\mathrm{N}$), $^{12}\mathrm{C}$($^{14}\mathrm{N}$, $^{13}\mathrm{C}$), $E=155$ MeV; $^{16}\mathrm{O}$($^{14}\mathrm{N}$, $^{13}\mathrm{N}$), $^{16}\mathrm{O}$($^{14}\mathrm{N}$, $^{13}\mathrm{C}$), $^{16}\mathrm{O}$($^{14}\mathrm{N}$, $^{15}\mathrm{N}$), $E=155$ MeV; $^{12}\mathrm{C}$($^{10}\mathrm{B}$, $^{11}\mathrm{B}$), $^{12}\mathrm{C}$($^{10}\mathrm{B}$, $^{11}\mathrm{C}$), $E=100$ MeV; $^{14}\mathrm{N}$($^{10}\mathrm{B}$, $^{11}\mathrm{B}$), $^{14}\mathrm{N}$($^{10}\mathrm{B}$, $^{11}\mathrm{C}$), $^{14}\mathrm{N}$($^{10}\mathrm{B}$, $^{9}\mathrm{Be}$), $E=100$ MeV; $^{16}\mathrm{O}$($^{10}\mathrm{B}$, $^{11}\mathrm{B}$), $^{16}\mathrm{O}$($^{10}\mathrm{B}$, $^{11}\mathrm{C}$), $^{16}\mathrm{O}$($^{10}\mathrm{B}$, $^{9}\mathrm{Be}$), $E=100$ MeV; measured $\ensuremath{\sigma}(\ensuremath{\theta})$; EFR DWBA analyses; extracted spectroscopic factors.