A model for orientation effects in electron‐transfer reactions

A method for solving the single‐particle Schrödinger equation with an oblate spheroidal potential of finite depth is presented. The wave functions are then used to calculate the matrix element T_BA which appears in theories of nonadiabatic electron transfer. The results illustrate the effects of mutual orientation and separation of the two centers on TBA. Trends in these results are discussed in terms of geometrical and nodal structure effects. Analytical expressions related to T_BA for states of spherical wells are presented and used to analyze the nodal structure effects for T_BA for the spheroidal wells

Deconstructing (2,0) proposals

C. P. is supported by the U.S. Department of Energy under Grant No. DE-FG02-96ER40959. M. S. S. is supported by an EURYI award of the European Science Foundatio

Conjugate gradient solvers on Intel Xeon Phi and NVIDIA GPUs

Lattice Quantum Chromodynamics simulations typically spend most of the runtime in inversions of the Fermion Matrix. This part is therefore frequently optimized for various HPC architectures. Here we compare the performance of the Intel Xeon Phi to current Kepler-based NVIDIA Tesla GPUs running a conjugate gradient solver. By exposing more parallelism to the accelerator through inverting multiple vectors at the same time, we obtain a performance greater than 300 GFlop/s on both architectures. This more than doubles the performance of the inversions. We also give a short overview of the Knights Corner architecture, discuss some details of the implementation and the effort required to obtain the achieved performance.Comment: 7 pages, proceedings, presented at 'GPU Computing in High Energy Physics', September 10-12, 2014, Pisa, Ital

Optomechanical creation of magnetic fields for photons on a lattice

We propose using the optomechanical interaction to create artificial magnetic fields for photons on a lattice. The ingredients required are an optomechanical crystal, i.e. a piece of dielectric with the right pattern of holes, and two laser beams with the right pattern of phases. One of the two proposed schemes is based on optomechanical modulation of the links between optical modes, while the other is an lattice extension of optomechanical wavelength-conversion setups. We illustrate the resulting optical spectrum, photon transport in the presence of an artificial Lorentz force, edge states, and the photonic Aharonov-Bohm effect. Moreover, wWe also briefly describe the gauge fields acting on the synthetic dimension related to the phonon/photon degree of freedom. These can be generated using a single laser beam impinging on an optomechanical array

Approximating parabolas as natural bounds of Heisenberg spectra: Reply on the comment of O. Waldmann

O. Waldmann has shown that some spin systems, which fulfill the condition of a weakly homogeneous coupling matrix, have a spectrum whose minimal or maximal energies are rather poorly approximated by a quadratic dependence on the total spin quantum number. We comment on this observation and provide the new argument that, under certain conditions, the approximating parabolas appear as natural bounds of the spectrum generated by spin coherent states.Comment: 2 pages, accepted for Europhysics Letter

On the neutrality issue in the Polyakov-loop NJL model

We elucidate how the color neutrality is harmed in the Polyakov Nambu-Jona Lasinio (PNJL) model at finite density within the adopted mean field approximation. Also we point out how usual assumption about the diagonal form of the Wilson loop may fail in the presence of the diquark condensate on several grounds.Comment: 8 pages, 1 figure. Introduction enlarged, several comments about the adopted mean field approximation and the relation with Elitzur's theorem added. Version to appear on Phys. Rev.