Real-time observation of interfering crystal electrons in high-harmonic generation

Accelerating and colliding particles has been a key strategy to explore the texture of matter. Strong lightwaves can control and recollide electronic wavepackets, generating high-harmonic (HH) radiation which encodes the structure and dynamics of atoms and molecules and lays the foundations of attosecond science. The recent discovery of HH generation in bulk solids combines the idea of ultrafast acceleration with complex condensed matter systems and sparks hope for compact solid-state attosecond sources and electronics at optical frequencies. Yet the underlying quantum motion has not been observable in real time. Here, we study HH generation in a bulk solid directly in the time-domain, revealing a new quality of strong-field excitations in the crystal. Unlike established atomic sources, our solid emits HH radiation as a sequence of subcycle bursts which coincide temporally with the field crests of one polarity of the driving terahertz waveform. We show that these features hallmark a novel non-perturbative quantum interference involving electrons from multiple valence bands. The results identify key mechanisms for future solid-state attosecond sources and next-generation lightwave electronics. The new quantum interference justifies the hope for all-optical bandstructure reconstruction and lays the foundation for possible quantum logic operations at optical clock rates

Sub-cycle quantum motion in solids under strong terahertz fields

In this thesis, non-perturbative charge carrier dynamics in crystalline solids have been explored in a novel coherent high-field regime bridging nonlinear optics and sub-cycle lightwave electronics. A newly developed high-field laser source delivers phase-stable, ultrashort waveforms in the far- to mid-infrared spectral regime with extremely high field strengths, which serve as a particularly well-defined contactless bias field for the study of non-perturbative charge carrier dynamics and nonlinear spin control in solids. To this end, a fundamentally new approach for ultrafast electric spin injection via tailored near-fields in a three-dimensional optical antenna has been introduced. First operational prototypes set the stage for time-resolved studies of spin-polarized tunnel injection into technologically relevant semiconductor heterostructures. Combining phase-locked waveforms featuring peak electric fields on the order of 100MV/cm with octave-spanning, 8-fs-long optical pulses facilitates lightwave electronics at multi-THz clock rates with sub-cycle time resolution: The strong transients have been employed to drive coherent interband excitation across the fundamental band gap in undoped gallium selenide. Simultaneously, the carriers are accelerated within their respective energy bands through the whole Brillouin zone, giving rise to dynamical Bloch oscillations. This highly anharmonic quantum motion results in the emission of a record-bandwidth, phase-stable high-order harmonic spectrum which covers more than 12 optical octaves. Yet more importantly, the terahertz-driven high-harmonic emission has been temporally resolved in intensity and relative phase and in precise correlation with the driving waveform. A novel cross-correlation scheme with synchronized electro-optic sampling clocks the underlying dynamics with an accuracy of only a fraction of 1/20 of a single driving field cycle: The high-order harmonics are emitted as a unipolar pulse train of ultrashort and nearly unchirped bursts, which emerge exactly at the driving field crests. As explained by a quantum-mechanical many-body theory, these findings reveal a novel strong-field quantum interference between several, off-resonantly driven interband polarization pathways, including even electronic transitions well below the Fermi level. A sophisticated examination of non-perturbative high-order harmonic generation along different crystallographic directions in gallium selenide has brought a surprising polarization behaviour of emitted harmonics to light. A phenomenological model based on the properties of frequency combs reconciles the spectrally, temporally and polarization-resolved findings and enables a comparison of the unraveled properties of solid-state high-order harmonic generation to straightforward symmetry arguments known from perturbative nonlinear optics

The effects of Bleomycin A5 on infantile maxillofacial haemangioma

<p>Abstract</p> <p>Objective</p> <p>To examine the effects of bleomycin A5 on infantile maxillofacial haemangiomas.</p> <p>Methods</p> <p>Bleomycin A5 was given by multiple intralesinoal injections and the dosage was given according to the age of the patient and size of the lesion. Parts of patients were accompanied by prednisone treatment(2-5 mg/kg, po, QOD.</p> <p>Results</p> <p>All the haemangiomas involuted completely after treated with bloemycin A5 with better recovery of skin color and less scar forming in small haemangiomas.</p> <p>Conclusion</p> <p>Infantile haemangioma could be effectively treated with bleomycin A5 without serious side effects.</p

Pyoderma Gangrenosum Associated with Sclerosing Cholangitis, Type 1 Diabetes Mellitus and Ulcerative Colitis

We describe the case of a 22-year-old black female with type 1 diabetes mellitus diagnosed when she was 12 years old. She first presented (March 1994) with pustules and ulcerations on the upper and lower limbs, trunk and scalp at the age 17. The diagnosis of pyoderma gangrenosum was made. Since presentation, changes in liver function were detected and subsequent study led to the diagnosis of sclerosing cholangitis. The diagnosis of ulcerative colitis was made after colonoscopy. Partial response was obtained with minocycline and clofazimine, but treatment with 5-aminosalicylic acid achieved no improvement of the ulcerations. Liver transplantation, followed by immunosuppressive therapy led to complete regression of the cutaneous lesions

Terahertz-Driven Nonlinear Spin Response of Antiferromagnetic Nickel Oxide

Terahertz magnetic fields with amplitudes of up to 0.4 Tesla drive magnon resonances in nickel oxide while the induced dynamics is recorded by femtosecond magneto-optical probing. We observe distinct spin-mediated optical nonlinearities, including oscillations at the second harmonic of the 1 THz magnon mode. The latter originate from coherent dynamics of the longitudinal component of the antiferromagnetic order parameter, which are probed by magneto-optical effects of second order in the spin deflection. These observations allow us to dynamically disentangle electronic from lattice-related contributions to magnetic linear birefringence and dichroism-information so far only accessible by ultrafast THz spin control. The nonlinearities discussed here foreshadow physics that will become essential in future subcycle spin switching

Symmetry-controlled temporal structure of high-harmonic carrier fields from a bulk crystal

High-harmonic (HH) generation in crystalline solids1, 2, 3, 4, 5, 6 marks an exciting development, with potential applications in high-efficiency attosecond sources7, all-optical bandstructure reconstruction8, 9 and quasiparticle collisions10, 11. Although the spectral1, 2, 3, 4 and temporal shape5 of the HH intensity has been described microscopically1, 2, 3, 4, 5, 6, 12, the properties of the underlying HH carrier wave have remained elusive. Here, we analyse the train of HH waveforms generated in a crystalline solid by consecutive half cycles of the same driving pulse. Extending the concept of frequency combs13, 14, 15 to optical clock rates, we show how the polarization and carrier-envelope phase (CEP) of HH pulses can be controlled by the crystal symmetry. For certain crystal directions, we can separate two orthogonally polarized HH combs mutually offset by the driving frequency to form a comb of even and odd harmonic orders. The corresponding CEP of successive pulses is constant or offset by π, depending on the polarization. In the context of a quantum description of solids, we identify novel capabilities for polarization- and phase-shaping of HH waveforms that cannot be accessed with gaseous sources