Circuit counts pulses and indicates time of occurrence of slow pulses

Counter includes one section which counts the first several pulses, and a second section which counts pulses from a clock between the beginning of a sampling interval and the receipt of the first pulse by the circuit. The number of clock pulses indicates receipt time of the first pulse

Counter Patent

Circuit for measuring wide range of pulse rates by utilizing high capacity counte

XUV lasing during strong-field assisted transient absorption in molecules

Using ab-initio non-Born-Oppenheimer simulations, we demonstrate amplification of XUV radiation in a high-harmonic generation type process using the example of the hydrogen molecular ion. A small fraction of the molecules is pumped to a dissociative Rydberg state from which IR-assisted XUV amplification is observed. We show that starting at sufficiently high IR driving field intensities the ground state molecules become quasi-transparent for XUV radiation, while due to stabilization gain from Rydberg states is maintained, thus leading to lasing from strongly driven Rydberg states. Further increase of the IR intensity even leads to gain by initially unexcited molecules, which are quickly excited by the driving IR pulse

Cotunneling and non-equilibrium magnetization in magnetic molecular monolayers

Transport and non-equilibrium magnetization in monolayers of magnetic molecules subject to a bias voltage are considered. We apply a master-equation approach going beyond the sequential-tunneling approximation to study the Coulomb-blockade regime. While the current is very small in this case, the magnetization shows changes of the order of the saturation magnetization for small variations of the bias voltage. Inelastic cotunneling processes manifest themselves as differential-conductance steps, which are accompanied by much larger changes in the magnetization. In addition, the magnetization in the Coulomb-blockade regime exhibits strong signatures of sequential tunneling processes de-exciting molecular states populated by inelastic cotunneling. We also consider the case of a single molecule, finding that cotunneling processes lead to the occurrence of magnetic sidebands below the Coulomb-blockade threshold. In the context of molecular electronics, we study how additional spin relaxation suppresses the fine structure in transport and magnetization.Comment: 8 pages, 8 figures, version as publishe

Liquid antiferromagnets in two dimensions

It is shown that, for proper symmetry of the parent lattice, antiferromagnetic order can survive in two-dimensional liquid crystals and even isotropic liquids of point-like particles, in contradiction to what common sense might suggest. We discuss the requirements for antiferromagnetic order in the absence of translational and/or orientational lattice order. One example is the honeycomb lattice, which upon melting can form a liquid crystal with quasi-long-range orientational and antiferromagnetic order but short-range translational order. The critical properties of such systems are discussed. Finally, we draw conjectures for the three-dimensional case.Comment: 4 pages RevTeX, 4 figures include

Doping dependence of the Neel temperature in Mott-Hubbard antiferromagnets: Effect of vortices

The rapid destruction of long-range antiferromagnetic order upon doping of Mott-Hubbard antiferromagnetic insulators is studied within a generalized Berezinskii-Kosterlitz-Thouless renormalization group theory in accordance with recent calculations suggesting that holes dress with vortices. We calculate the doping-dependent Neel temperature in good agreement with experiments for high-Tc cuprates. Interestingly, the critical doping where long-range order vanishes at zero temperature is predicted to be xc ~ 0.02, independently of any energy scales of the system.Comment: 4 pages with 3 figures included, minor revisions, to be published in PR