The laser-induced femtosecond demagnetization in ferromagnetic metals is investigated theoretically. Different from the conventional nanosecond one, this ultrafast demagnetization is a cooperative effect of the external laser field and the internal spin-orbit coupling. The spin-orbit coupling smears out the original identities of triplets and singlets while the laser field uses it as an avenue ...

We demonstrate a cryogenically cooled Ti:sapphire ultrafast regenerative amplifier laser system producing >20 μJ energies at 50 kHz, >12 μJ at 200 kHz and >3.5 μJ at 1MHz with repetition rates continuously tunable from 50 kHz up to 1.7 MHz in a footprint of only 60x180 cm². This laser uses down-chirped pulse amplification employing a grism stretcher and a glass-block compressor, achieving sub-6...

The outstanding charge transport properties of graphene enable numerous electronic applications of this remarkable material, many of which are expected to operate at ultrahigh speeds. In the regime of ultrafast, sub-picosecond electric fields, however, the very high conduction properties of graphene are not necessarily preserved, with the physical picture explaining this behaviour remaining unc...

Actively all-optical tunable plasmon-induced transparency in metamaterials paves the way for achieving ultrahigh-speed quantum information processing chips. Unfortunately, up to now, very small experimental progress has been made for all-optical tunable plasmon-induced transparency in metamaterials in the visible and near-infrared range because of small third-order optical nonlinearity of conve...

A series of chemically functionalized porous aromatic frameworks (PAFs) have been synthesized and deployed within mixedmatrix membranes for gas separation. This series of PAFs delivered for the first time simultaneous control of selective gas transport and physical aging within the membranes. New composites including native and metalated fullerenes were also prepared, and the composites exhibit...

Protein folding is a diffusional process, and the speed of folding is controlled by the frictional forces that act on the polypeptide chain. Several previous studies have suggested that the bulk viscosity of the solvent is the only important source of friction in folding reactions. By contrast, our studies of the folding dynamics of the Tryptophan Cage, a small, ultrafast-folding protein, show ...

In condensed matter systems, strong optical excitations can induce phonon-driven processes that alter their mechanical properties. We report on a new phenomenon where a massive electronic excitation induces a collective change in the bond character that leads to transient lattice contraction. Single large van der Waals clusters were isochorically heated to a nanoplasma state with an intense 10-...

Photosensitivity is a material property that is relevant to many phenomena and applications, from photosynthesis and photography to optical data storage and ultrafast laser writing. It was commonly thought that, in a homogeneous medium, photosensitivity and the corresponding light-induced material modifications do not change on reversing the direction of light propagation. Here we demonstrate t...

We present the first direct measurement of ultrafast charge migration in a biomolecular building block - the amino acid phenylalanine. Using an extreme ultraviolet pulse of 1.5 fs duration to ionize molecules isolated in the gas phase, the location of the resulting hole was probed by a 6 fs visible/near-infrared pulse. By measuring the yield of a doubly charged ion as a function of the delay be...

A programmable optical computer has remained an elusive concept. To construct a practical computing primitive equivalent to an electronic Boolean logic, one should find a nonlinear phenomenon that overcomes weaknesses present in many optical processing schemes. Ideally, the nonlinearity should provide a functionally complete set of logic operations, enable ultrafast all-optical programmability,...