Non-perturbative Interband Response of InSb Driven Off-resonantly by Few-cycle Electromagnetic Transients

Intense multi-THz pulses are used to study the coherent nonlinear response of bulk InSb by means of field-resolved four-wave mixing spectroscopy. At amplitudes above 5 MV/cm the signals show a clear temporal substructure which is unexpected in perturbative nonlinear optics. Simulations based on a two-level quantum system demonstrate that in spite of the strongly off-resonant character of the excitation the high-field pulses drive the interband resonances into a non-perturbative regime of Rabi flopping.Comment: 4 pages, 4 figure

Femoral nerve compression secondary to a ganglion cyst arising from a hip joint: a case report and review of the literature

<p>Abstract</p> <p>Introduction</p> <p>Femoral nerve compression due to a cystic lesion around the hip joint is rare and only a few cases have been described in the literature. Among these, true ganglion cysts are even more rare.</p> <p>Case presentation</p> <p>We report the case of a 57-year-old woman with femoral nerve compression caused by a true ganglion cyst of the hip joint.</p> <p>Conclusion</p> <p>A high index of suspicion is required to predict a non-palpable cystic lesion around the hip joint as it may mimic different disorders and should be kept in mind in the differential diagnosis of unusual groin pain, radicular pain and peripheral vascular disorders.</p

High-field high-repetition-rate sources for the coherent THz control of matter

Ultrashort flashes of THz light with low photon energies of a few meV, but strong electric or magnetic field transients have recently been employed to prepare various fascinating nonequilibrium states in matter. Here we present a new class of sources based on superradiant enhancement of radiation from relativistic electron bunches in a compact electron accelerator that we believe will revolutionize experiments in this field. Our prototype source generates high-field THz pulses at unprecedented quasicontinuous-wave repetition rates up to the MHz regime. We demonstrate parameters that exceed state-of-the-art laser-based sources by more than 2 orders of magnitude. The peak fields and the repetition rates are highly scalable and once fully operational this type of sources will routinely provide 1 MV/cm electric fields and 0.3 T magnetic fields at repetition rates of few 100 kHz. We benchmark the unique properties by performing a resonant coherent THz control experiment with few 10 fs resolution

Birth, death, and revival of spontaneous emission in a three-atom system

Three identical two-level atoms in free space prepared in particular entangled single-photon excited states display a “birth,” “death,” and a nonperiodic “revival” of spontaneous emission in selected directions. Instead of recording the spontaneously emitted photon with a maximum probability at t=0 as for a single atom, a “birth” manifests itself in an initially zero photon detection probability, increasing thereafter in particular directions. Alternatively, the photon detection probability decreases in particular directions from an initially maximal value to completely disappear (“death”) and to reappear again (“revival”). We show how these phenomena can be induced in the fully excited system, by projecting the atomic ensemble into the required entangled single-photon excited state via detection of the first two spontaneously emitted photons. To observe death and revival of spontaneous emission it is necessary to provide both spatial and temporal interference for which a minimum of three atoms is required. Hereby, the third atom, located at a large distance with respect to the other two atoms, can be used to tune the time and direction of the death of the photon. From this manipulation of spontaneous decay at a distance, we anticipate multiple applications, in fundamental science as well as in quantum technologies